getParsed NullPointerException / Version 7

# Conflicts:
#	.idea/misc.xml
#	app/src/main/java/de/sebse/fuplanner/MainActivity.java
#	app/src/main/java/de/sebse/fuplanner/fragments/ScheduleFragment.java

.gitignore

@@ -1,8 +1,8 @@
 *.iml
 .gradle
 /local.properties
-/.idea/workspace.xml
-/.idea/libraries
+/.idea/*
+/.idea - PC/*
 .DS_Store
 /build
 /captures

.idea/codeStyles/Project.xml

@@ -1,29 +0,0 @@
-<component name="ProjectCodeStyleConfiguration">
-  <code_scheme name="Project" version="173">
-    <Objective-C-extensions>
-      <file>
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Import" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Macro" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Typedef" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Enum" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Constant" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Global" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Struct" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="FunctionPredecl" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Function" />
-      </file>
-      <class>
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Property" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Synthesize" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="InitMethod" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="StaticMethod" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="InstanceMethod" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="DeallocMethod" />
-      </class>
-      <extensions>
-        <pair source="cpp" header="h" fileNamingConvention="NONE" />
-        <pair source="c" header="h" fileNamingConvention="NONE" />
-      </extensions>
-    </Objective-C-extensions>
-  </code_scheme>
-</component>

.idea/gradle.xml

@@ -1,18 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="GradleSettings">
-    <option name="linkedExternalProjectsSettings">
-      <GradleProjectSettings>
-        <option name="distributionType" value="DEFAULT_WRAPPED" />
-        <option name="externalProjectPath" value="$PROJECT_DIR$" />
-        <option name="modules">
-          <set>
-            <option value="$PROJECT_DIR$" />
-            <option value="$PROJECT_DIR$/app" />
-          </set>
-        </option>
-        <option name="resolveModulePerSourceSet" value="false" />
-      </GradleProjectSettings>
-    </option>
-  </component>
-</project>

.idea/misc.xml

@@ -1,29 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="NullableNotNullManager">
-    <option name="myDefaultNullable" value="android.support.annotation.Nullable" />
-    <option name="myDefaultNotNull" value="android.support.annotation.NonNull" />
-    <option name="myNullables">
-      <value>
-        <list size="5">
-          <item index="0" class="java.lang.String" itemvalue="org.jetbrains.annotations.Nullable" />
-          <item index="1" class="java.lang.String" itemvalue="javax.annotation.Nullable" />
-          <item index="2" class="java.lang.String" itemvalue="javax.annotation.CheckForNull" />
-          <item index="3" class="java.lang.String" itemvalue="edu.umd.cs.findbugs.annotations.Nullable" />
-          <item index="4" class="java.lang.String" itemvalue="android.support.annotation.Nullable" />
-        </list>
-      </value>
-    </option>
-    <option name="myNotNulls">
-      <value>
-        <list size="4">
-          <item index="0" class="java.lang.String" itemvalue="org.jetbrains.annotations.NotNull" />
-          <item index="1" class="java.lang.String" itemvalue="javax.annotation.Nonnull" />
-          <item index="2" class="java.lang.String" itemvalue="edu.umd.cs.findbugs.annotations.NonNull" />
-          <item index="3" class="java.lang.String" itemvalue="android.support.annotation.NonNull" />
-        </list>
-      </value>
-    </option>
-  </component>
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_8" default="true" project-jdk-name="1.8" project-jdk-type="JavaSDK" />
-</project>

.idea/modules.xml

@@ -1,9 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="ProjectModuleManager">
-    <modules>
-      <module fileurl="file://$PROJECT_DIR$/.idea/FUPlanner.iml" filepath="$PROJECT_DIR$/.idea/FUPlanner.iml" />
-      <module fileurl="file://$PROJECT_DIR$/app/app.iml" filepath="$PROJECT_DIR$/app/app.iml" />
-    </modules>
-  </component>
-</project>

.idea/runConfigurations.xml

@@ -1,12 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="RunConfigurationProducerService">
-    <option name="ignoredProducers">
-      <set>
-        <option value="org.jetbrains.plugins.gradle.execution.test.runner.AllInPackageGradleConfigurationProducer" />
-        <option value="org.jetbrains.plugins.gradle.execution.test.runner.TestClassGradleConfigurationProducer" />
-        <option value="org.jetbrains.plugins.gradle.execution.test.runner.TestMethodGradleConfigurationProducer" />
-      </set>
-    </option>
-  </component>
-</project>

.idea/vcs.xml

@@ -1,7 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="VcsDirectoryMappings">
-    <mapping directory="" vcs="Git" />
-    <mapping directory="$PROJECT_DIR$" vcs="Git" />
-  </component>
-</project>

app/build.gradle

@@ -2,14 +2,14 @@ apply plugin: 'com.android.application'
 
 android {
     compileSdkVersion 28
-    buildToolsVersion '27.0.3'
+    buildToolsVersion '28.0.3'
     defaultConfig {
         applicationId "de.sebse.fuplanner"
         minSdkVersion 15
         targetSdkVersion 28
-        versionCode 1
-        versionName "1.0"
-        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
+        versionCode 7
+        versionName "1.1.5"
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
     buildTypes {
         release {
@@ -27,24 +27,24 @@ android {
 
 
 dependencies {
-    implementation 'com.android.support:recyclerview-v7:28.0.0-rc01'
+    implementation 'androidx.recyclerview:recyclerview:1.0.0'
     implementation fileTree(include: ['*.jar'], dir: 'libs')
-    androidTestImplementation('com.android.support.test.espresso:espresso-core:2.2.2', {
+    androidTestImplementation('androidx.test.espresso:espresso-core:3.1.0-beta02', {
         exclude group: 'com.android.support', module: 'support-annotations'
     })
-    implementation 'com.android.support:appcompat-v7:28.0.0-rc01'
-    implementation 'com.android.support:preference-v7:28.0.0-rc01'
-    implementation 'com.android.support:design:28.0.0-rc01'
-    implementation 'com.android.support.constraint:constraint-layout:1.1.2'
-    implementation 'com.android.volley:volley:1.0.0'
+    implementation 'androidx.appcompat:appcompat:1.0.0'
+    implementation 'androidx.preference:preference:1.0.0'
+    implementation 'com.google.android.material:material:1.0.0'
+    implementation 'androidx.constraintlayout:constraintlayout:2.0.0-alpha2'
+    implementation 'com.android.volley:volley:1.1.0'
     //noinspection GradleDependency
     implementation 'com.google.android.gms:play-services-auth:15.0.0'
-    implementation 'com.android.support:support-v4:28.0.0-rc01'
+    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
     testImplementation 'junit:junit:4.12'
     implementation fileTree(include: ['*.jar'], dir: 'libs')
-    implementation 'com.android.support:appcompat-v7:28.0.0-rc01'
+    implementation 'androidx.appcompat:appcompat:1.0.0'
     implementation 'org.jbundle.util.osgi.wrapped:org.jbundle.util.osgi.wrapped.org.apache.http.client:4.1.2'
-    implementation 'com.android.support:support-v4:28.0.0-rc01'
+    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
     implementation 'org.jetbrains:annotations-java5:15.0'
     //implementation 'com.github.quivr:android-week-view:2.0.2'//com.github.alamkanak:android-week-view:1.2.6
     implementation 'com.ms-square:expandableTextView:0.1.4'

app/src/androidTest/java/de/sebse/fuplanner/ExampleInstrumentedTest.java

@@ -1,12 +1,13 @@
 package de.sebse.fuplanner;
 
 import android.content.Context;
-import android.support.test.InstrumentationRegistry;
-import android.support.test.runner.AndroidJUnit4;
 
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
+import androidx.test.InstrumentationRegistry;
+import androidx.test.runner.AndroidJUnit4;
+
 import static org.junit.Assert.*;
 
 /**

app/src/main/AndroidManifest.xml

@@ -4,6 +4,9 @@
 
     <uses-permission android:name="android.permission.INTERNET" />
 
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
+
+
     <application
         android:allowBackup="true"
         android:icon="@mipmap/ic_launcher"

app/src/main/java/de/sebse/fuplanner/MainActivity.java

@@ -2,24 +2,27 @@ package de.sebse.fuplanner;
 
 import android.content.Intent;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.annotation.StringRes;
-import android.support.design.widget.NavigationView;
-import android.support.v4.app.Fragment;
-import android.support.v4.app.FragmentManager;
-import android.support.v4.app.FragmentTransaction;
-import android.support.v4.view.GravityCompat;
-import android.support.v4.widget.DrawerLayout;
-import android.support.v7.app.ActionBarDrawerToggle;
-import android.support.v7.app.AppCompatActivity;
-import android.support.v7.widget.Toolbar;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.View;
 import android.widget.TextView;
+import android.widget.Toast;
 
+import com.google.android.material.navigation.NavigationView;
+
+import java.util.HashMap;
 import java.util.Iterator;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.StringRes;
+import androidx.appcompat.app.ActionBarDrawerToggle;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.appcompat.widget.Toolbar;
+import androidx.core.view.GravityCompat;
+import androidx.drawerlayout.widget.DrawerLayout;
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentManager;
+import androidx.fragment.app.FragmentTransaction;
 import de.sebse.fuplanner.fragments.CanteensFragment;
 import de.sebse.fuplanner.fragments.LoginFragment;
 import de.sebse.fuplanner.fragments.ModulesFragment;
@@ -34,11 +37,12 @@ import de.sebse.fuplanner.services.GoogleAuth.GoogleAuth;
 import de.sebse.fuplanner.services.KVV.KVV;
 import de.sebse.fuplanner.services.KVV.types.LoginToken;
 import de.sebse.fuplanner.services.KVV.types.Modules;
-import de.sebse.fuplanner.tools.MainAcitivityListener;
+import de.sebse.fuplanner.tools.MainActivityListener;
+import de.sebse.fuplanner.tools.RequestPermissionsResultListener;
 import de.sebse.fuplanner.tools.logging.Logger;
 
 public class MainActivity extends AppCompatActivity
-        implements MainAcitivityListener,
+        implements MainActivityListener,
         NavigationView.OnNavigationItemSelectedListener,
         LoginFragment.OnLoginFragmentInteractionListener,
         ModulesFragment.OnModulesFragmentInteractionListener,
@@ -64,9 +68,11 @@ public class MainActivity extends AppCompatActivity
     private NavigationView mNavigationView;
 
     private int fragmentPage = FRAGMENT_NONE;
+    private int currentPage = FRAGMENT_NONE;
     private String fragmentData = "";
     private CanteenBrowser mCanteenBrowser;
     private boolean mOfflineMode = false;
+    private HashMap<String, RequestPermissionsResultListener> permissionListeners = new HashMap<>();
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -93,24 +99,14 @@ public class MainActivity extends AppCompatActivity
         mFragmentManager = getSupportFragmentManager();
 
         LoginToken loginToken = getKVV().easyLogin();
-        if (newFragmentPage != FRAGMENT_LOGIN && newFragmentPage != FRAGMENT_STARTUP && newFragmentPage != FRAGMENT_NONE) {
-            if (loginToken != null)
+        if (loginToken == null) {
+            checkAndDoLogin();
+        } else {
+            if (newFragmentPage != FRAGMENT_LOGIN && newFragmentPage != FRAGMENT_STARTUP && newFragmentPage != FRAGMENT_NONE)
                 toLoginState(loginToken, newFragmentPage, newFragmentData);
             else
-                checkAndDoLogin();
-        } else {
-            if (loginToken != null)
                 toLoginState(loginToken, getDefaultFragmentAfterLogin(), "");
-            else
-                checkAndDoLogin();
         }
-
-        /*this.getCanteenBrowser().getCanteens(success -> {
-            Canteen canteen = success.get(0);
-            this.getCanteenBrowser().getCanteen(canteen, success1 -> {
-                this.getCanteenBrowser().getDay(canteen.get(0), log::d, log::e, true);
-            }, log::e, true);
-        }, log::e, true);*/
     }
 
     @Override
@@ -126,7 +122,7 @@ public class MainActivity extends AppCompatActivity
     @Override
     public boolean onCreateOptionsMenu(Menu menu) {
         // Inflate the menu; this adds items to the action bar if it is present.
-        if (fragmentPage == FRAGMENT_SCHEDULE) {
+        if (currentPage == FRAGMENT_SCHEDULE) {
             getMenuInflater().inflate(R.menu.options_schedule, menu);
             return true;
         }
@@ -162,7 +158,6 @@ public class MainActivity extends AppCompatActivity
     public boolean onNavigationItemSelected(@NonNull MenuItem item) {
         // Handle navigation view item clicks here.
         int id = item.getItemId();
-
         switch (id) {
             case R.id.nav_modules:
                 changeFragment(FRAGMENT_MODULES);
@@ -192,8 +187,8 @@ public class MainActivity extends AppCompatActivity
                     this.toLogoutState();
                 });
                 break;
-        }
 
+        }
         DrawerLayout drawer = findViewById(R.id.drawer_layout);
         drawer.closeDrawer(GravityCompat.START);
 
@@ -214,11 +209,24 @@ public class MainActivity extends AppCompatActivity
 
     @Override
     protected void onSaveInstanceState(Bundle savedInstanceState) {
+        Fragment fragment = mFragmentManager.findFragmentByTag(String.valueOf(fragmentPage));
         savedInstanceState.putInt(ARG_FRAGMENT_PAGE, fragmentPage);
         savedInstanceState.putString(ARG_FRAGMENT_STATUS, fragmentData);
+        if (fragment instanceof ModDetailFragment) {
+            savedInstanceState.putString(ARG_FRAGMENT_STATUS, ((ModDetailFragment) fragment).getData());
+        } else {
+            savedInstanceState.putString(ARG_FRAGMENT_STATUS, fragmentData);
+        }
         super.onSaveInstanceState(savedInstanceState);
     }
 
+    @Override
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
+        for (RequestPermissionsResultListener listener: permissionListeners.values()) {
+            listener.callback(requestCode, permissions, grantResults);
+        }
+    }
+
     /* --------------------------------------------*/
     /* --------------------------------------------*/
     /* --------------------------------------------*/
@@ -245,7 +253,18 @@ public class MainActivity extends AppCompatActivity
     }
 
     private int getDefaultFragmentAfterLogin() {
-        return FRAGMENT_MODULES;
+        return getDefaultFragmentAfterLogin(new String[1]);
+    }
+
+    private int getDefaultFragmentAfterLogin(String[] id) {
+        if (fragmentPage == FRAGMENT_NONE){
+            id[0] = "";
+            return FRAGMENT_MODULES;
+        }
+        else {
+            id[0] = fragmentData;
+            return fragmentPage;
+        }
     }
 
     private void toLogoutState() {
@@ -257,15 +276,16 @@ public class MainActivity extends AppCompatActivity
         if (loginToken == null) {
             toLogoutState();
         } else {
-            toLoginState(loginToken.getFullname(), loginToken.getEmail(), newFragment, newData, true);
+            toLoginState(loginToken.getFullName(), loginToken.getEmail(), newFragment, newData, true);
         }
     }
 
-    private void toLoginState(String fullname, String email, int newFragment, String newData, boolean onlineMode) {
+    private void toLoginState(String fullName, String email, int newFragment, String newData, boolean onlineMode) {
+        log.d(currentPage, newFragment);
         changeFragment(newFragment, newData);
 
         View header = mNavigationView.getHeaderView(0);
-        ((TextView) header.findViewById(R.id.login_name)).setText(fullname);
+        ((TextView) header.findViewById(R.id.login_name)).setText(fullName);
         ((TextView) header.findViewById(R.id.login_mail)).setText(email);
         setOfflineBanner(onlineMode);
     }
@@ -277,7 +297,10 @@ public class MainActivity extends AppCompatActivity
                 toLogoutState();
                 return;
             }
-            this.getKVV().login(credentials.getUsername(), credentials.getPassword(), success -> toLoginState(success, getDefaultFragmentAfterLogin(), ""),
+            String[] id = {""};
+
+            int fragment = getDefaultFragmentAfterLogin(id);
+            this.getKVV().login(credentials.getUsername(), credentials.getPassword(), success -> toLoginState(success, fragment , id[0]),
             error -> {
                 log.e(error);
                 toLogoutState();
@@ -290,27 +313,35 @@ public class MainActivity extends AppCompatActivity
     }
 
     private void changeFragment(int newFragment, String newData) {
-        onTitleTextChange(R.string.courses);
+        if (mFragmentManager.isStateSaved())
+            return;
+        if (newFragment == FRAGMENT_CANTEENS_DETAILS && newData.equals(""))
+            newFragment = FRAGMENT_CANTEENS;
+        if (newFragment == FRAGMENT_MODULES_DETAILS && newData.equals(""))
+            newFragment = FRAGMENT_MODULES;
+
+        //log.d("changeFragment: ", newFragment, newData);
+        onTitleTextChange(R.string.app_name);
         Fragment fragment;
         switch (newFragment) {
-            case FRAGMENT_MODULES:
-                fragment = ModulesFragment.newInstance();
-                break;
             case FRAGMENT_MODULES_DETAILS:
                 fragment = ModDetailFragment.newInstance(newData);
                 break;
+            case FRAGMENT_MODULES:
+                fragment = ModulesFragment.newInstance();
+                break;
             case FRAGMENT_LOGIN:
                 fragment = LoginFragment.newInstance();
                 break;
             case FRAGMENT_SCHEDULE:
                 fragment = ScheduleFragment.newInstance();
                 break;
-            case FRAGMENT_CANTEENS:
-                fragment = CanteensFragment.newInstance();
-                break;
             case FRAGMENT_CANTEENS_DETAILS:
                 fragment = DaySwitcherFragment.newInstance(Integer.parseInt(newData));
                 break;
+            case FRAGMENT_CANTEENS:
+                fragment = CanteensFragment.newInstance();
+                break;
             case FRAGMENT_PREFERENCES:
                 fragment = PrefsFragment.newInstance();
                 break;
@@ -329,7 +360,7 @@ public class MainActivity extends AppCompatActivity
             findViewById(R.id.app_bar_layout).setVisibility(View.VISIBLE);
         }
         // switch to logout
-        if ((fragmentPage != FRAGMENT_STARTUP && fragmentPage != FRAGMENT_LOGIN) && (newFragment == FRAGMENT_STARTUP || newFragment == FRAGMENT_LOGIN)) {
+        if ((currentPage != FRAGMENT_STARTUP && currentPage != FRAGMENT_LOGIN) && (newFragment == FRAGMENT_STARTUP || newFragment == FRAGMENT_LOGIN)) {
             View header = mNavigationView.getHeaderView(0);
             //header.findViewById(R.id.imageView).setVisibility(View.GONE);
             header.findViewById(R.id.login_name).setVisibility(View.GONE);
@@ -346,7 +377,10 @@ public class MainActivity extends AppCompatActivity
             mNavigationView.inflateMenu(R.menu.activity_main_drawer);
             afterAnyMenuInflate();
         } // switch to login
-        else if ((fragmentPage == FRAGMENT_STARTUP || fragmentPage == FRAGMENT_LOGIN || fragmentPage == FRAGMENT_NONE) && (newFragment != FRAGMENT_STARTUP && newFragment != FRAGMENT_LOGIN && newFragment != FRAGMENT_CANTEENS && newFragment != FRAGMENT_CANTEENS_DETAILS)) {
+        else if (
+                (currentPage == FRAGMENT_STARTUP || currentPage == FRAGMENT_LOGIN || currentPage == FRAGMENT_NONE) &&
+                (newFragment != FRAGMENT_STARTUP && newFragment != FRAGMENT_LOGIN && getKVV().isLoggedIn())
+                ) {
             View header = mNavigationView.getHeaderView(0);
             //header.findViewById(R.id.imageView).setVisibility(View.VISIBLE);
             header.findViewById(R.id.login_name).setVisibility(View.VISIBLE);
@@ -391,8 +425,11 @@ public class MainActivity extends AppCompatActivity
             }, log::e);
         }
 
-        this.fragmentPage = newFragment;
-        this.fragmentData = newData;
+        if (newFragment != FRAGMENT_STARTUP && newFragment != FRAGMENT_NONE && newFragment != FRAGMENT_LOGIN) {
+            this.fragmentPage = newFragment;
+            this.fragmentData = newData;
+        }
+        this.currentPage = newFragment;
         invalidateOptionsMenu();
     }
 
@@ -436,31 +473,68 @@ public class MainActivity extends AppCompatActivity
 
 
     public void onLoginFragmentInteraction(LoginToken loginToken, boolean onlineMode) {
-        toLoginState(loginToken.getFullname(), loginToken.getEmail(), getDefaultFragmentAfterLogin(), "", onlineMode);
+        String[] id = {""};
+        int fragment = getDefaultFragmentAfterLogin(id);
+        toLoginState(loginToken.getFullName(), loginToken.getEmail(), fragment, id[0], onlineMode);
     }
 
+    @Override
     public void onModulesFragmentInteraction(final String itemID) {
         changeFragment(FRAGMENT_MODULES_DETAILS, itemID);
     }
 
+    @Override
     public void onCanteensFragmentInteraction(final int itemID) {
         changeFragment(FRAGMENT_CANTEENS_DETAILS, String.valueOf(itemID));
     }
 
+    @Override
     public void onTitleTextChange(String newTitle) {
         setTitle(newTitle);
     }
 
+    @Override
     public void onTitleTextChange(@StringRes int titleId) {
         setTitle(titleId);
     }
 
-    public void loginTokenInvalid(boolean doPrecheck) {
-        getKVV().invalidate();
-        checkAndDoLogin();
+    @Override
+    public void loginTokenInvalid(boolean doLoginCheck) {
+        if (doLoginCheck) {
+            getKVV().testLogin(isSuccess -> {
+                if (!isSuccess) {
+                    getKVV().invalidate();
+                    checkAndDoLogin();
+                }
+            });
+        } else {
+            getKVV().invalidate();
+            checkAndDoLogin();
+        }
     }
 
-    public void refreshFailed(boolean isFailed) {
+    @Override
+    public void onRefreshCompleted(boolean isFailed) {
         setRefreshFailedBanner(isFailed);
     }
+
+    @Override
+    public void addRequestPermissionsResultListener(RequestPermissionsResultListener listener, String id) {
+        permissionListeners.put(id, listener);
+    }
+
+    @Override
+    public void removeRequestPermissionsResultListener(String id) {
+        permissionListeners.remove(id);
+    }
+
+    @Override
+    public void showToast(@StringRes int msgStringRes) {
+        showToast(getString(msgStringRes));
+    }
+
+    @Override
+    public void showToast(String message) {
+        Toast.makeText(this, message, Toast.LENGTH_SHORT).show();
+    }
 }

app/src/main/java/de/sebse/fuplanner/fragments/CanteensAdapter.java

@@ -1,11 +1,11 @@
 package de.sebse.fuplanner.fragments;
 
-import android.support.annotation.NonNull;
-import android.support.v7.widget.RecyclerView;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.RecyclerView;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.fragments.CanteensFragment.OnCanteensFragmentInteractionListener;
 import de.sebse.fuplanner.services.Canteen.types.Canteen;

app/src/main/java/de/sebse/fuplanner/fragments/CanteensFragment.java

@@ -2,19 +2,19 @@ package de.sebse.fuplanner.fragments;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.v4.app.Fragment;
-import android.support.v4.widget.SwipeRefreshLayout;
-import android.support.v7.widget.LinearLayoutManager;
-import android.support.v7.widget.RecyclerView;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
+import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
+import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;
 import de.sebse.fuplanner.MainActivity;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.Canteen.CanteenBrowser;
-import de.sebse.fuplanner.tools.MainAcitivityListener;
+import de.sebse.fuplanner.tools.MainActivityListener;
 import de.sebse.fuplanner.tools.logging.Logger;
 
 /**
@@ -87,8 +87,8 @@ public class CanteensFragment extends Fragment {
             throw new RuntimeException(context.toString()
                     + " must implement OnCanteensFragmentInteractionListener");
         }
-        if (context instanceof MainAcitivityListener)
-            ((MainAcitivityListener) context).onTitleTextChange(R.string.canteens);
+        if (context instanceof MainActivityListener)
+            ((MainActivityListener) context).onTitleTextChange(R.string.canteens);
         else
             throw new RuntimeException(context.toString() + "must implement MainActivityListener");
     }

app/src/main/java/de/sebse/fuplanner/fragments/LoginFragment.java

@@ -3,8 +3,6 @@ package de.sebse.fuplanner.fragments;
 import android.app.ProgressDialog;
 import android.content.Context;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.v4.app.Fragment;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -13,13 +11,15 @@ import android.widget.EditText;
 
 import java.io.IOException;
 
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
 import de.sebse.fuplanner.MainActivity;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.GoogleAuth.GoogleAuth;
 import de.sebse.fuplanner.services.KVV.KVV;
 import de.sebse.fuplanner.services.KVV.types.LoginToken;
 import de.sebse.fuplanner.services.KVV.types.Modules;
-import de.sebse.fuplanner.tools.MainAcitivityListener;
+import de.sebse.fuplanner.tools.MainActivityListener;
 import de.sebse.fuplanner.tools.logging.Logger;
 
 /**
@@ -33,6 +33,7 @@ import de.sebse.fuplanner.tools.logging.Logger;
 public class LoginFragment extends Fragment {
     private OnLoginFragmentInteractionListener mListener;
     private final Logger log = new Logger(this);
+    private MainActivityListener mActivityListener;
 
     public LoginFragment() {
         // Required empty public constructor
@@ -96,10 +97,23 @@ public class LoginFragment extends Fragment {
                     kvv.login(username, password, success -> {
                         progressDialog.dismiss();
                         gauth.setLoginState(username, password);
-                        if (mListener != null)
+                        if (mListener != null) {
+                            input_usr.setError(null);
+                            input_pwd.setError(null);
                             mListener.onLoginFragmentInteraction(success, true);
+                        }
                     }, error -> {
                         progressDialog.dismiss();
+                        // Invalid password
+                        if (mActivityListener != null) {
+                            if (error.getCode() == 100131) {
+                                mActivityListener.showToast(R.string.invalid_credentials);
+                                input_usr.setError(input_usr.getResources().getString(R.string.invalid_credentials));
+                                input_pwd.setError(input_pwd.getResources().getString(R.string.invalid_credentials));
+                            } else {
+                                mActivityListener.showToast(v.getResources().getString(R.string.error_occurred_code, error.getCode()));
+                            }
+                        }
                         log.e("Error on KVV login!", error);
                     });
                 }
@@ -120,9 +134,10 @@ public class LoginFragment extends Fragment {
             throw new RuntimeException(context.toString()
                     + " must implement OnLoginFragmentInteractionListener");
         }
-        if (context instanceof MainAcitivityListener)
-            ((MainAcitivityListener) context).onTitleTextChange(R.string.courses);
-        else
+        if (context instanceof MainActivityListener) {
+            mActivityListener = (MainActivityListener) context;
+            mActivityListener.onTitleTextChange(R.string.log_in);
+        } else
             throw new RuntimeException(context.toString() + "must implement MainActivityListener");
     }
 

app/src/main/java/de/sebse/fuplanner/fragments/ModulesAdapter.java

@@ -1,11 +1,11 @@
 package de.sebse.fuplanner.fragments;
 
-import android.support.annotation.NonNull;
-import android.support.v7.widget.RecyclerView;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.RecyclerView;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.fragments.ModulesFragment.OnModulesFragmentInteractionListener;
 import de.sebse.fuplanner.services.KVV.types.Modules;

app/src/main/java/de/sebse/fuplanner/fragments/ModulesFragment.java

@@ -2,19 +2,19 @@ package de.sebse.fuplanner.fragments;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.v4.app.Fragment;
-import android.support.v4.widget.SwipeRefreshLayout;
-import android.support.v7.widget.LinearLayoutManager;
-import android.support.v7.widget.RecyclerView;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
+import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
+import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;
 import de.sebse.fuplanner.MainActivity;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.KVV.KVV;
-import de.sebse.fuplanner.tools.MainAcitivityListener;
+import de.sebse.fuplanner.tools.MainActivityListener;
 import de.sebse.fuplanner.tools.logging.Logger;
 
 /**
@@ -87,8 +87,8 @@ public class ModulesFragment extends Fragment {
             throw new RuntimeException(context.toString()
                     + " must implement OnModulesFragmentInteractionListener");
         }
-        if (context instanceof MainAcitivityListener)
-            ((MainAcitivityListener) context).onTitleTextChange(R.string.courses);
+        if (context instanceof MainActivityListener)
+            ((MainActivityListener) context).onTitleTextChange(R.string.courses);
         else
             throw new RuntimeException(context.toString() + "must implement MainActivityListener");
     }

app/src/main/java/de/sebse/fuplanner/fragments/PrefsFragment.java

@@ -2,9 +2,9 @@ package de.sebse.fuplanner.fragments;
 
 import android.content.SharedPreferences;
 import android.os.Bundle;
-import android.support.v7.preference.ListPreference;
-import android.support.v7.preference.Preference;
-import android.support.v7.preference.PreferenceFragmentCompat;
+import androidx.preference.ListPreference;
+import androidx.preference.Preference;
+import androidx.preference.PreferenceFragmentCompat;
 
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.tools.logging.Logger;

app/src/main/java/de/sebse/fuplanner/fragments/ScheduleFragment.java

@@ -4,8 +4,6 @@ import android.app.AlertDialog;
 import android.content.Context;
 import android.graphics.RectF;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.v4.app.Fragment;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -15,12 +13,14 @@ import java.util.Calendar;
 import java.util.Iterator;
 import java.util.List;
 
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.KVV.KVV;
 import de.sebse.fuplanner.services.KVV.types.Event;
 import de.sebse.fuplanner.services.KVV.types.Modules;
-import de.sebse.fuplanner.tools.DateUtils;
-import de.sebse.fuplanner.tools.MainAcitivityListener;
+import de.sebse.fuplanner.tools.UtilsDate;
+import de.sebse.fuplanner.tools.MainActivityListener;
 import de.sebse.fuplanner.tools.logging.Logger;
 import de.sebse.fuplanner.tools.ui.weekview.MonthLoader;
 import de.sebse.fuplanner.tools.ui.weekview.WeekView;
@@ -29,14 +29,14 @@ import de.sebse.fuplanner.tools.ui.weekview.WeekViewEvent;
 /**
  * A simple {@link Fragment} subclass.
  * Activities that contain this fragment must implement the
- * {@link MainAcitivityListener} interface
+ * {@link MainActivityListener} interface
  * to handle interaction events.
  * Use the {@link ScheduleFragment#newInstance} factory method to
  * create an instance of this fragment.
  *
  */
 public class ScheduleFragment extends Fragment implements MonthLoader.MonthChangeListener, WeekView.ScrollListener, WeekView.DoubleTapListener, WeekView.EventClickListener {
-    private MainAcitivityListener mListener;
+    private MainActivityListener mListener;
     private WeekView mWeekView;
     private final Logger log = new Logger(this);
     private Modules mModules = null;
@@ -99,8 +99,8 @@ public class ScheduleFragment extends Fragment implements MonthLoader.MonthChang
     @Override
     public void onAttach(Context context) {
         super.onAttach(context);
-        if (context instanceof MainAcitivityListener) {
-            mListener = (MainAcitivityListener) context;
+        if (context instanceof MainActivityListener) {
+            mListener = (MainActivityListener) context;
         } else {
             throw new RuntimeException(context.toString()
                     + " must implement OnFragmentInteractionListener");
@@ -144,7 +144,7 @@ public class ScheduleFragment extends Fragment implements MonthLoader.MonthChang
     public void onFirstVisibleDayChanged(Calendar newFirstVisibleDay, Calendar oldFirstVisibleDay) {
         Calendar newLastVisibleDay = (Calendar) newFirstVisibleDay.clone();
         newLastVisibleDay.add(Calendar.HOUR, 24*mWeekView.getNumberOfVisibleDays());
-        mListener.onTitleTextChange(getResources().getString(R.string.date_scale, DateUtils.getModifiedDate(newFirstVisibleDay.getTimeInMillis()), DateUtils.getModifiedDate(newLastVisibleDay.getTimeInMillis())));
+        mListener.onTitleTextChange(getResources().getString(R.string.date_scale, UtilsDate.getModifiedDate(newFirstVisibleDay.getTimeInMillis()), UtilsDate.getModifiedDate(newLastVisibleDay.getTimeInMillis())));
     }
 
 
@@ -157,9 +157,11 @@ public class ScheduleFragment extends Fragment implements MonthLoader.MonthChang
         Calendar firstVisibleDay = mWeekView.getFirstVisibleDay();
         Calendar c = Calendar.getInstance();
         c.set(firstVisibleDay.get(Calendar.YEAR), firstVisibleDay.get(Calendar.MONTH), firstVisibleDay.get(Calendar.DAY_OF_MONTH), 0,0 );
-        c.add(Calendar.DATE, 2); // die Grenze beim tippen, wann ver nach vorne und wann nach hinten springt
+        // Limit when to go a week backwards and when to the next week
+        c.add(Calendar.DATE, 2);
 
-        if (c.getTimeInMillis() > time.getTimeInMillis()){//nach links blättern
+        // skip to next week
+        if (c.getTimeInMillis() > time.getTimeInMillis()){
             firstVisibleDay.add(Calendar.DATE, -1);
             while (firstVisibleDay.get(Calendar.DAY_OF_WEEK) != Calendar.MONDAY) {
                 firstVisibleDay.add(Calendar.DATE, -1);
@@ -172,6 +174,7 @@ public class ScheduleFragment extends Fragment implements MonthLoader.MonthChang
             }
         }
         mWeekView.goToDate(firstVisibleDay);
+        onFirstVisibleDayChanged(firstVisibleDay, mWeekView.getLastVisibleDay());
     }
 
     @Override
@@ -190,7 +193,7 @@ public class ScheduleFragment extends Fragment implements MonthLoader.MonthChang
                         .setMessage(
                                 getResources().getString(R.string.module_name, moduleName) + "\n" +
                                         getResources().getString(R.string.location_name, event.getLocation()) + "\n" +
-                                        getResources().getString(R.string.date_scale, DateUtils.getModifiedTime(getContext(), event.getStartTime().getTimeInMillis()), DateUtils.getModifiedTime(getContext(), event.getEndTime().getTimeInMillis()+1))
+                                        getResources().getString(R.string.date_scale, UtilsDate.getModifiedTime(getContext(), event.getStartTime().getTimeInMillis()), UtilsDate.getModifiedTime(getContext(), event.getEndTime().getTimeInMillis()+1))
                         )
                         .setCancelable(true)
                         .setNeutralButton(R.string.close, (dialog, id) -> dialog.cancel());

app/src/main/java/de/sebse/fuplanner/fragments/StartupFragment.java

@@ -1,12 +1,12 @@
 package de.sebse.fuplanner.fragments;
 
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.v4.app.Fragment;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
 import de.sebse.fuplanner.R;
 
 /**

app/src/main/java/de/sebse/fuplanner/fragments/canteen/DaySwitcherAdapter.java

@@ -1,11 +1,11 @@
 package de.sebse.fuplanner.fragments.canteen;
 
-import android.support.v4.app.Fragment;
-import android.support.v4.app.FragmentManager;
-import android.support.v4.app.FragmentStatePagerAdapter;
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentManager;
+import androidx.fragment.app.FragmentStatePagerAdapter;
 
 import de.sebse.fuplanner.services.Canteen.types.Canteen;
-import de.sebse.fuplanner.tools.DateUtils;
+import de.sebse.fuplanner.tools.UtilsDate;
 
 class DaySwitcherAdapter extends FragmentStatePagerAdapter {
     private Canteen mCanteen = null;
@@ -39,7 +39,7 @@ class DaySwitcherAdapter extends FragmentStatePagerAdapter {
     // Returns the page title for the top indicator
     @Override
     public CharSequence getPageTitle(int position) {
-        return DateUtils.getModifiedDate(mCanteen.get(position).getCalendar().getTimeInMillis());
+        return UtilsDate.getModifiedDate(mCanteen.get(position).getCalendar().getTimeInMillis());
     }
 
 }

app/src/main/java/de/sebse/fuplanner/fragments/canteen/DaySwitcherFragment.java

@@ -2,18 +2,18 @@ package de.sebse.fuplanner.fragments.canteen;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.v4.app.Fragment;
-import android.support.v4.view.ViewPager;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
+import androidx.viewpager.widget.ViewPager;
 import de.sebse.fuplanner.MainActivity;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.Canteen.CanteenBrowser;
 import de.sebse.fuplanner.services.Canteen.types.Canteen;
-import de.sebse.fuplanner.tools.MainAcitivityListener;
+import de.sebse.fuplanner.tools.MainActivityListener;
 import de.sebse.fuplanner.tools.logging.Logger;
 import de.sebse.fuplanner.tools.network.NetworkCallback;
 import de.sebse.fuplanner.tools.network.NetworkErrorCallback;
@@ -21,7 +21,7 @@ import de.sebse.fuplanner.tools.network.NetworkErrorCallback;
 /**
  * A simple {@link Fragment} subclass.
  * Activities that contain this fragment must implement the
- * {@link MainAcitivityListener} interface
+ * {@link MainActivityListener} interface
  * to handle interaction events.
  * Use the {@link DaySwitcherFragment#newInstance} factory method to
  * create an instance of this fragment.
@@ -32,9 +32,8 @@ public class DaySwitcherFragment extends Fragment implements DaySwitcherListener
     // Parameters
     private int mCanteenId;
 
-    private MainAcitivityListener mListener;
+    private MainActivityListener mListener;
     private final Logger log = new Logger(this);
-    private ViewPager mViewPager;
     private DaySwitcherAdapter adapterViewPager;
 
     public DaySwitcherFragment() {
@@ -78,11 +77,11 @@ public class DaySwitcherFragment extends Fragment implements DaySwitcherListener
         // Inflate the layout for this fragment
         View v = inflater.inflate(R.layout.fragment_mod_detail, container, false);
 
-        mViewPager = v.findViewById(R.id.vpPager);
+        ViewPager mViewPager = v.findViewById(R.id.vpPager);
         adapterViewPager = new DaySwitcherAdapter(getChildFragmentManager());
         mViewPager.setAdapter(adapterViewPager);
 
-        refresh(false);
+        refresh();
 
         return v;
     }
@@ -90,8 +89,8 @@ public class DaySwitcherFragment extends Fragment implements DaySwitcherListener
     @Override
     public void onAttach(Context context) {
         super.onAttach(context);
-        if (context instanceof MainAcitivityListener) {
-            mListener = (MainAcitivityListener) context;
+        if (context instanceof MainActivityListener) {
+            mListener = (MainActivityListener) context;
         } else {
             throw new RuntimeException(context.toString()
                     + " must implement MainActivityListener");
@@ -104,8 +103,8 @@ public class DaySwitcherFragment extends Fragment implements DaySwitcherListener
         mListener = null;
     }
 
-    private void refresh(boolean forceRefresh) {
-        refresh(forceRefresh, null, null);
+    private void refresh() {
+        refresh(false, null, null);
     }
 
     private void refresh(boolean forceRefresh, NetworkCallback<Canteen> callback, NetworkErrorCallback errorCallback) {
@@ -113,6 +112,7 @@ public class DaySwitcherFragment extends Fragment implements DaySwitcherListener
             CanteenBrowser browser = ((MainActivity) getActivity()).getCanteenBrowser();
             browser.getCanteens(canteens -> {
                 Canteen canteen = canteens.getCanteen(mCanteenId);
+                canteen.cleanUpDays();
                 adapterViewPager.setModule(canteen);
                 browser.getCanteen(canteen, success -> {
                     adapterViewPager.setModule();

app/src/main/java/de/sebse/fuplanner/fragments/canteen/MealAdapter.java

@@ -4,16 +4,28 @@ import android.content.Context;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
-import android.widget.BaseExpandableListAdapter;
 
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.StringRes;
+import androidx.recyclerview.widget.RecyclerView;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.Canteen.types.Day;
 import de.sebse.fuplanner.services.Canteen.types.Meal;
 import de.sebse.fuplanner.tools.Preferences;
-import de.sebse.fuplanner.tools.ui.ItemViewHolder;
+import de.sebse.fuplanner.tools.ui.MealViewHolder;
 import de.sebse.fuplanner.tools.ui.StringViewHolder;
 
-class MealAdapter extends BaseExpandableListAdapter {
+class MealAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
+    private String[] CATEGORY_KEYS = new String[]{"Essen", "Aktionen", "Beilagen", "Desserts", "Salate", "Suppen", "Vorspeisen"};
+    @StringRes
+    private int[] CATEGORY_VALS = new int[]{R.string.meals, R.string.special_meals, R.string.side_dishes, R.string.desserts, R.string.salads, R.string.soups, R.string.starters};
+    @StringRes
+    private int CATEGORY_OTHER = R.string.others;
+    private ArrayList<Object> matches = new ArrayList<>();
 
     private Day mDay = null;
     private final Context mContext;
@@ -22,105 +34,105 @@ class MealAdapter extends BaseExpandableListAdapter {
         mContext = context;
     }
 
+    @NonNull
     @Override
-    public String getChild(int groupPosition, int childPosititon) {
-        StringBuilder sb = new StringBuilder();
-        sb.append("\n\n");
-        for (String s : this.getGroup(groupPosition).getNotes())
-        {
-            sb.append(s);
-            sb.append("\n\n");
+    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType) {
+        if (viewType == 0) {
+            View view = LayoutInflater.from(viewGroup.getContext())
+                    .inflate(R.layout.list_canteen_items, viewGroup, false);
+            return new MealViewHolder(view);
+        } else {
+            View view = LayoutInflater.from(viewGroup.getContext())
+                    .inflate(R.layout.list_all_caption, viewGroup, false);
+            return new StringViewHolder(view);
         }
-        return sb.toString();
     }
 
     @Override
-    public long getChildId(int groupPosition, int childPosition) {
-        return childPosition;
-    }
-
-    @Override
-    public View getChildView(int groupPosition, final int childPosition,
-                             boolean isLastChild, View convertView, ViewGroup parent) {
-
-        final String childText = getChild(groupPosition, childPosition);
-
-        if (convertView == null) {
-            convertView = LayoutInflater.from(parent.getContext())
-                    .inflate(R.layout.list_all_string, parent, false);
+    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
+        if (holder.getItemViewType() == 0) {
+            MealViewHolder viewHolder = ((MealViewHolder) holder);
+            viewHolder.reset();
+            Meal meal = getMeal(position);
+            viewHolder.mTitle.setText(meal.getName());
+            String value;
+            switch (Preferences.getString(mContext, R.array.pref_price_group)) {
+                case "student":
+                    if (meal.getPriceStdnt() < 0)
+                        value = mContext.getResources().getString(R.string.no_price_available);
+                    else
+                        value = mContext.getString(R.string.price, meal.getPriceStdnt());
+                    break;
+                case "employee":
+                    if (meal.getPriceEmply() < 0)
+                        value = mContext.getResources().getString(R.string.no_price_available);
+                    else
+                        value = mContext.getString(R.string.price, meal.getPriceEmply());
+                    break;
+                case "other":
+                    if (meal.getPriceOther() < 0)
+                        value = mContext.getResources().getString(R.string.no_price_available);
+                    else
+                        value = mContext.getString(R.string.price, meal.getPriceOther());
+                    break;
+                default:
+                    String value1;
+                    if (meal.getPriceStdnt() < 0)
+                        value1 = " -/- ";
+                    else
+                        value1 = mContext.getString(R.string.price, meal.getPriceStdnt());
+                    String value2;
+                    if (meal.getPriceEmply() < 0)
+                        value2 = " -/- ";
+                    else
+                        value2 = mContext.getString(R.string.price, meal.getPriceEmply());
+                    String value3;
+                    if (meal.getPriceOther() < 0)
+                        value3 = " -/- ";
+                    else
+                        value3 = mContext.getString(R.string.price, meal.getPriceOther());
+                        value = mContext.getString(R.string.prices, value1, value2, value3);
+            }
+            viewHolder.mSubTitle.setText(value);
+            StringBuilder string = new StringBuilder();
+            List<String> notes = meal.getNotes();
+            for (int i1 = 0, notesSize = notes.size(); i1 < notesSize; i1++) {
+                if (i1 != 0)
+                    string.append("\n");
+                String s = notes.get(i1);
+                string.append(" - ").append(s);
+            }
+            viewHolder.mNotes.setText(string.toString());
+            viewHolder.mCategory.setText(meal.getCategory());
+            viewHolder.mIconVegan.setVisibility(meal.getVegan() == Meal.VEGAN_VEGAN ? View.VISIBLE : View.GONE);
+            viewHolder.mIconVegetarian.setVisibility(meal.getVegan() == Meal.VEGAN_VEGETARIAN ? View.VISIBLE : View.GONE);
+            viewHolder.mIconBio.setVisibility((meal.getCertificates() & Meal.CERT_BIO) != 0 ? View.VISIBLE : View.GONE);
+            viewHolder.mIconMsc.setVisibility((meal.getCertificates() & Meal.CERT_MSC) != 0 ? View.VISIBLE : View.GONE);
+        } else {
+            StringViewHolder viewHolder = ((StringViewHolder) holder);
+            viewHolder.mString.setText(getHeading(position));
         }
-
-        StringViewHolder itemHolder = new StringViewHolder(convertView);
-        itemHolder.mString.setText(childText);
-
-        return convertView;
     }
 
     @Override
-    public int getChildrenCount(int groupPosition) {
-        return 1;
+    public int getItemCount() {
+        return matches.size();
     }
 
     @Override
-    public Meal getGroup(int groupPosition) {
+    public int getItemViewType(int position) {
+        return matches.get(position) instanceof String ? 1 : 0;
+    }
+
+    private Meal getMeal(int position) {
         if (this.mDay != null)
-            return this.mDay.get(groupPosition);
+            return this.mDay.get((Integer) matches.get(position));
         else
             return null;
     }
 
-    @Override
-    public int getGroupCount() {
-        if (this.mDay != null)
-            return this.mDay.size();
-        else
-            return 0;
-    }
-
-    @Override
-    public long getGroupId(int groupPosition) {
-        return groupPosition;
-    }
-
-    @Override
-    public View getGroupView(int groupPosition, boolean isExpanded,
-                             View convertView, ViewGroup parent) {
-        Meal meal = getGroup(groupPosition);
-        if (convertView == null) {
-            convertView = LayoutInflater.from(parent.getContext())
-                    .inflate(R.layout.list_all_items, parent, false);
-        }
-
-        ItemViewHolder itemHolder = new ItemViewHolder(convertView);
-        itemHolder.mTitle.setText(meal.getName());
-        itemHolder.mSubLeft.setText(meal.getCategory());
-        String value;
-        switch (Preferences.getString(mContext, R.array.pref_price_group)) {
-            case "student":
-                value = mContext.getString(R.string.price, meal.getPriceStdnt());
-                break;
-            case "employee":
-                value = mContext.getString(R.string.price, meal.getPriceEmply());
-                break;
-            case "other":
-                value = mContext.getString(R.string.price, meal.getPriceOther());
-                break;
-            default:
-                value = mContext.getString(R.string.prices, meal.getPriceStdnt(), meal.getPriceEmply(), meal.getPriceOther());
-        }
-        itemHolder.mSubRight.setText(value);
-
-        return convertView;
-    }
-
-    @Override
-    public boolean hasStableIds() {
-        return false;
-    }
-
-    @Override
-    public boolean isChildSelectable(int groupPosition, int childPosition) {
-        return false;
+    private String getHeading(int position) {
+        return (String) matches.get(position);
     }
 
     public void setDay(Day day) {
@@ -129,6 +141,37 @@ class MealAdapter extends BaseExpandableListAdapter {
     }
 
     public void setDay() {
+        HashMap<String, ArrayList<Integer>> map = new HashMap<>();
+        for (int i = 0; i < this.mDay.size(); i++) {
+            String category = this.mDay.get(i).getCategory();
+            boolean found = false;
+            for (String category_key : CATEGORY_KEYS) {
+                if (category_key.equals(category)) {
+                    found = true;
+                    break;
+                }
+            }
+            if (!found) category = "---";
+            ArrayList<Integer> list = map.get(category);
+            if (list == null) {
+                list = new ArrayList<>();
+                map.put(category, list);
+            }
+            list.add(i);
+        }
+        matches.clear();
+        for (int i = 0; i < CATEGORY_KEYS.length; i++) {
+            ArrayList<Integer> list = map.get(CATEGORY_KEYS[i]);
+            if (list != null) {
+                matches.add(mContext.getString(CATEGORY_VALS[i]));
+                matches.addAll(list);
+            }
+        }
+        ArrayList<Integer> list = map.get("---");
+        if (list != null) {
+            matches.add(mContext.getString(CATEGORY_OTHER));
+            matches.addAll(list);
+        }
         this.notifyDataSetChanged();
     }
 }

app/src/main/java/de/sebse/fuplanner/fragments/canteen/MealFragment.java

@@ -3,14 +3,14 @@ package de.sebse.fuplanner.fragments.canteen;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.v4.app.Fragment;
-import android.support.v4.widget.SwipeRefreshLayout;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
-import android.widget.ExpandableListView;
 
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
+import androidx.recyclerview.widget.RecyclerView;
+import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;
 import de.sebse.fuplanner.MainActivity;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.Canteen.CanteenBrowser;
@@ -43,9 +43,9 @@ public class MealFragment extends Fragment {
      * Use this factory method to create a new instance of
      * this fragment using the provided parameters.
      *
-     * @param canteenId Item position in module list.
-     * @param dayPosition Item position in module list.
-     * @return A new instance of fragment ModDetailAnnounceFragment.
+     * @param canteenId ID od current canteen.
+     * @param dayPosition day to show.
+     * @return A new instance of fragment MealFragment.
      */
     public static MealFragment newInstance(int canteenId, int dayPosition) {
         MealFragment fragment = new MealFragment();
@@ -69,9 +69,9 @@ public class MealFragment extends Fragment {
     public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container,
                              Bundle savedInstanceState) {
         // Inflate the layout for this fragment
-        View view = inflater.inflate(R.layout.fragment_expandable_list_view, container, false);
+        View view = inflater.inflate(R.layout.fragment_recycler_view, container, false);
         // Set the adapter
-        ExpandableListView expandableListView = view.findViewById(R.id.list);
+        RecyclerView expandableListView = view.findViewById(R.id.list);
         adapter = new MealAdapter(getContext());
         expandableListView.setAdapter(adapter);
 

app/src/main/java/de/sebse/fuplanner/fragments/moddetails/ModDetailAdapter.java

@@ -1,9 +1,9 @@
 package de.sebse.fuplanner.fragments.moddetails;
 
 import android.content.Context;
-import android.support.v4.app.Fragment;
-import android.support.v4.app.FragmentManager;
-import android.support.v4.app.FragmentStatePagerAdapter;
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentManager;
+import androidx.fragment.app.FragmentStatePagerAdapter;
 
 import de.sebse.fuplanner.R;
 
@@ -38,6 +38,8 @@ class ModDetailAdapter extends FragmentStatePagerAdapter {
                 return ModDetailEventFragment.newInstance(mItemPos);
             case ModulePart.GRADEBOOK:
                 return ModDetailGradebookFragment.newInstance(mItemPos);
+            case ModulePart.RESOURCES:
+                return ModDetailResourceFragment.newInstance(mItemPos);
             default:
                 return null;
         }
@@ -57,6 +59,8 @@ class ModDetailAdapter extends FragmentStatePagerAdapter {
                 return this.mContext.getResources().getString(R.string.events);
             case ModulePart.GRADEBOOK:
                 return this.mContext.getResources().getString(R.string.gradebook);
+            case ModulePart.RESOURCES:
+                return this.mContext.getResources().getString(R.string.resources);
             default:
                 return "";
         }

app/src/main/java/de/sebse/fuplanner/fragments/moddetails/ModDetailAnnounceAdapter.java

@@ -10,7 +10,7 @@ import java.util.ArrayList;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.KVV.types.Announcement;
 import de.sebse.fuplanner.services.KVV.types.Modules;
-import de.sebse.fuplanner.tools.DateUtils;
+import de.sebse.fuplanner.tools.UtilsDate;
 import de.sebse.fuplanner.tools.ui.ItemViewHolder;
 import de.sebse.fuplanner.tools.ui.StringViewHolder;
 
@@ -19,7 +19,7 @@ class ModDetailAnnounceAdapter extends BaseExpandableListAdapter {
     private Modules.Module mModule = null;
 
     @Override
-    public String getChild(int groupPosition, int childPosititon) {
+    public String getChild(int groupPosition, int childPosition) {
         StringBuilder s = new StringBuilder(this.getGroup(groupPosition).getBody());
         ArrayList<String> urls = this.getGroup(groupPosition).getUrls();
         for (int j =0; j<urls.size(); j++){
@@ -89,7 +89,7 @@ class ModDetailAnnounceAdapter extends BaseExpandableListAdapter {
         ItemViewHolder itemHolder = new ItemViewHolder(convertView);
         itemHolder.mTitle.setText(announce.getTitle());
         itemHolder.mSubLeft.setText(announce.getCreatedBy());
-        itemHolder.mSubRight.setText(DateUtils.getModifiedDateTime(parent.getContext(), announce.getCreatedOn()));
+        itemHolder.mSubRight.setText(UtilsDate.getModifiedDateTime(parent.getContext(), announce.getCreatedOn()));
 
         return convertView;
     }

app/src/main/java/de/sebse/fuplanner/fragments/moddetails/ModDetailAnnounceFragment.java

@@ -2,14 +2,14 @@ package de.sebse.fuplanner.fragments.moddetails;
 
 
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.v4.app.Fragment;
-import android.support.v4.widget.SwipeRefreshLayout;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ExpandableListView;
 
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
+import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;
 import de.sebse.fuplanner.MainActivity;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.KVV.KVV;

app/src/main/java/de/sebse/fuplanner/fragments/moddetails/ModDetailAssignmentAdapter.java

@@ -8,7 +8,7 @@ import android.widget.BaseExpandableListAdapter;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.KVV.types.Assignment;
 import de.sebse.fuplanner.services.KVV.types.Modules;
-import de.sebse.fuplanner.tools.DateUtils;
+import de.sebse.fuplanner.tools.UtilsDate;
 import de.sebse.fuplanner.tools.ui.ItemViewHolder;
 import de.sebse.fuplanner.tools.ui.StringViewHolder;
 
@@ -17,7 +17,7 @@ class ModDetailAssignmentAdapter extends BaseExpandableListAdapter {
     private Modules.Module mModule = null;
 
     @Override
-    public String getChild(int groupPosition, int childPosititon) {
+    public String getChild(int groupPosition, int childPosition) {
         StringBuilder sb = new StringBuilder();
         sb.append(this.getGroup(groupPosition).getInstructions());
         sb.append("\n\n");
@@ -92,7 +92,7 @@ class ModDetailAssignmentAdapter extends BaseExpandableListAdapter {
             itemHolder.mSubLeft.setText(itemHolder.mView.getResources().getText(R.string.open));
         else
             itemHolder.mSubLeft.setText(itemHolder.mView.getResources().getText(R.string.closed));
-        itemHolder.mSubRight.setText(DateUtils.getModifiedDateTime(parent.getContext(), assignment.getDueDate()));
+        itemHolder.mSubRight.setText(UtilsDate.getModifiedDateTime(parent.getContext(), assignment.getDueDate()));
 
         return convertView;
     }

app/src/main/java/de/sebse/fuplanner/fragments/moddetails/ModDetailAssignmentFragment.java

@@ -2,14 +2,14 @@ package de.sebse.fuplanner.fragments.moddetails;
 
 
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.v4.app.Fragment;
-import android.support.v4.widget.SwipeRefreshLayout;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ExpandableListView;
 
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
+import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;
 import de.sebse.fuplanner.MainActivity;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.KVV.KVV;

app/src/main/java/de/sebse/fuplanner/fragments/moddetails/ModDetailEventAdapter.java

@@ -1,21 +1,21 @@
 package de.sebse.fuplanner.fragments.moddetails;
 
-import android.support.annotation.NonNull;
-import android.support.v7.widget.RecyclerView;
 import android.util.Pair;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
-import android.widget.TextView;
 
 import java.util.ArrayList;
 
+import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.RecyclerView;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.KVV.types.Event;
 import de.sebse.fuplanner.services.KVV.types.Modules;
-import de.sebse.fuplanner.tools.DateUtils;
-import de.sebse.fuplanner.tools.ui.CustomViewHolder;
+import de.sebse.fuplanner.tools.UtilsDate;
+import de.sebse.fuplanner.tools.logging.Logger;
 import de.sebse.fuplanner.tools.ui.ItemViewHolder;
+import de.sebse.fuplanner.tools.ui.StringViewHolder;
 
 class ModDetailEventAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
     private static final int TYPE_HEADER = 0;
@@ -27,6 +27,8 @@ class ModDetailEventAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder
     private Modules.Module mValue;
     private final ArrayList<Pair<Integer, Integer>> mPositionalData;
 
+    private final Logger log = new Logger(this);
+
     ModDetailEventAdapter() {
         mValue = null;
         mPositionalData = new ArrayList<>();
@@ -61,7 +63,7 @@ class ModDetailEventAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder
             case TYPE_HEADER:
                 view = LayoutInflater.from(parent.getContext())
                         .inflate(R.layout.list_all_caption, parent, false);
-                return new HeaderViewHolder(view);
+                return new StringViewHolder(view);
             case TYPE_ITEM:
                 view = LayoutInflater.from(parent.getContext())
                         .inflate(R.layout.list_all_items, parent, false);
@@ -87,13 +89,13 @@ class ModDetailEventAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder
         Pair<Integer, Integer> data = mPositionalData.get(position);
         switch (data.first) {
             case TYPE_HEADER:
-                HeaderViewHolder h = (HeaderViewHolder) holder;
+                StringViewHolder h = (StringViewHolder) holder;
                 switch (data.second) {
                     case SECTION_PAST:
-                        h.mCaption.setText(R.string.past_events);
+                        h.mString.setText(R.string.past_events);
                         break;
                     case SECTION_UPCOMING:
-                        h.mCaption.setText(R.string.upcoming_events);
+                        h.mString.setText(R.string.upcoming_events);
                         break;
                 }
                 break;
@@ -114,14 +116,14 @@ class ModDetailEventAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder
                 i.mTitle.setText(event.getTitle());
                 i.mSubLeft.setText(event.getType());
                 String start, end;
-                if (DateUtils.dateEquals(event.getStartDate(), System.currentTimeMillis()))
-                    start = DateUtils.getModifiedTime(i.mView.getContext(), event.getStartDate());
+                if (UtilsDate.dateEquals(event.getStartDate(), System.currentTimeMillis()))
+                    start = UtilsDate.getModifiedTime(i.mView.getContext(), event.getStartDate());
                 else
-                    start = DateUtils.getModifiedDateTime(i.mView.getContext(), event.getStartDate());
-                if (DateUtils.dateEquals(event.getStartDate(), event.getEndDate()))
-                    end = DateUtils.getModifiedTime(i.mView.getContext(), event.getEndDate());
+                    start = UtilsDate.getModifiedDateTime(i.mView.getContext(), event.getStartDate());
+                if (UtilsDate.dateEquals(event.getStartDate(), event.getEndDate()))
+                    end = UtilsDate.getModifiedTime(i.mView.getContext(), event.getEndDate());
                 else
-                    end = DateUtils.getModifiedDateTime(i.mView.getContext(), event.getEndDate());
+                    end = UtilsDate.getModifiedDateTime(i.mView.getContext(), event.getEndDate());
                 i.mSubRight.setText(i.mView.getResources().getString(R.string.date_scale,
                         start, end
                 ));
@@ -145,27 +147,4 @@ class ModDetailEventAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder
             return mValue.events.sizePast();
         return 0;
     }
-
-
-
-
-
-
-
-
-    class HeaderViewHolder extends CustomViewHolder {
-        final TextView mCaption;
-
-        HeaderViewHolder(View view) {
-            super(view);
-            mCaption = view.findViewById(R.id.caption);
-        }
-
-        @Override
-        public String toString() {
-            return super.toString() + " '" + mCaption.getText() + "'";
-        }
-    }
-
-
 }

app/src/main/java/de/sebse/fuplanner/fragments/moddetails/ModDetailEventFragment.java

@@ -3,15 +3,15 @@ package de.sebse.fuplanner.fragments.moddetails;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.v4.app.Fragment;
-import android.support.v4.widget.SwipeRefreshLayout;
-import android.support.v7.widget.LinearLayoutManager;
-import android.support.v7.widget.RecyclerView;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
+import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
+import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;
 import de.sebse.fuplanner.MainActivity;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.KVV.KVV;

app/src/main/java/de/sebse/fuplanner/fragments/moddetails/ModDetailFragment.java

@@ -2,22 +2,22 @@ package de.sebse.fuplanner.fragments.moddetails;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.v4.app.Fragment;
-import android.support.v4.view.ViewPager;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
+import androidx.viewpager.widget.ViewPager;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.KVV.types.Modules;
-import de.sebse.fuplanner.tools.MainAcitivityListener;
+import de.sebse.fuplanner.tools.MainActivityListener;
 import de.sebse.fuplanner.tools.logging.Logger;
 
 /**
  * A simple {@link Fragment} subclass.
  * Activities that contain this fragment must implement the
- * {@link MainAcitivityListener} interface
+ * {@link MainActivityListener} interface
  * to handle interaction events.
  * Use the {@link ModDetailFragment#newInstance} factory method to
  * create an instance of this fragment.
@@ -28,9 +28,10 @@ public class ModDetailFragment extends Fragment implements ModDetailListener {
     // Parameters
     private String mItemPos;
 
-    private MainAcitivityListener mListener;
+    private MainActivityListener mListener;
     private final Logger log = new Logger(this);
     private ViewPager mViewPager;
+    private String mPageRestoreRequest = null;
 
     public ModDetailFragment() {
         // Required empty public constructor
@@ -46,7 +47,11 @@ public class ModDetailFragment extends Fragment implements ModDetailListener {
     public static Fragment newInstance(String itemPosition) {
         ModDetailFragment fragment = new ModDetailFragment();
         Bundle args = new Bundle();
-        args.putString(ARG_POSITION, itemPosition);
+        if (!itemPosition.contains("."))
+            args.putString(ARG_POSITION, itemPosition+"."+0);
+        else
+            args.putString(ARG_POSITION, itemPosition);
+
         fragment.setArguments(args);
         return fragment;
     }
@@ -55,7 +60,15 @@ public class ModDetailFragment extends Fragment implements ModDetailListener {
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         if (getArguments() != null) {
-            mItemPos = getArguments().getString(ARG_POSITION);
+            String itemPosition = getArguments().getString(ARG_POSITION);
+            if (!itemPosition.contains(".")) {
+                mItemPos = itemPosition;
+                mPageRestoreRequest = null;
+            } else {
+                String[] split = itemPosition.split("\\.", 2);
+                mItemPos = split[0];
+                mPageRestoreRequest = split[1];
+            }
         }
         if (mListener != null) {
             mListener.onTitleTextChange(R.string.courses);
@@ -76,14 +89,16 @@ public class ModDetailFragment extends Fragment implements ModDetailListener {
         mViewPager = v.findViewById(R.id.vpPager);
         ModDetailAdapter adapterViewPager = new ModDetailAdapter(getChildFragmentManager(), mItemPos, getContext());
         mViewPager.setAdapter(adapterViewPager);
+        if (mPageRestoreRequest != null)
+            mViewPager.setCurrentItem(Integer.parseInt(mPageRestoreRequest));
         return v;
     }
 
     @Override
     public void onAttach(Context context) {
         super.onAttach(context);
-        if (context instanceof MainAcitivityListener) {
-            mListener = (MainAcitivityListener) context;
+        if (context instanceof MainActivityListener) {
+            mListener = (MainActivityListener) context;
         } else {
             throw new RuntimeException(context.toString()
                     + " must implement MainActivityListener");
@@ -100,4 +115,8 @@ public class ModDetailFragment extends Fragment implements ModDetailListener {
     public void gotoFragmentPart(int part, int index) {
         mViewPager.setCurrentItem(ModulePart.getPageByPart(part), true);
     }
+
+    public String getData() {
+        return mItemPos+"."+mViewPager.getCurrentItem();
+    }
 }

app/src/main/java/de/sebse/fuplanner/fragments/moddetails/ModDetailGradebookAdapter.java

@@ -1,8 +1,6 @@
 package de.sebse.fuplanner.fragments.moddetails;
 
 import android.annotation.SuppressLint;
-import android.support.annotation.NonNull;
-import android.support.v7.widget.RecyclerView;
 import android.util.Pair;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -11,10 +9,12 @@ import android.widget.TextView;
 
 import java.util.ArrayList;
 
+import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.RecyclerView;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.KVV.types.Gradebook;
 import de.sebse.fuplanner.services.KVV.types.Modules;
-import de.sebse.fuplanner.tools.ui.CustomViewHolder;
+import de.sebse.fuplanner.tools.ui.StringViewHolder;
 
 class ModDetailGradebookAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
     private static final int TYPE_TOTAL = 0;
@@ -58,10 +58,10 @@ class ModDetailGradebookAdapter extends RecyclerView.Adapter<RecyclerView.ViewHo
             case TYPE_TOTAL:
                 view = LayoutInflater.from(parent.getContext())
                         .inflate(R.layout.list_all_caption, parent, false);
-                return new HeaderViewHolder(view);
+                return new StringViewHolder(view);
             case TYPE_GRADE:
                 view = LayoutInflater.from(parent.getContext())
-                        .inflate(R.layout.list_modetails_gradebook, parent, false);
+                        .inflate(R.layout.list_moddetails_gradebook, parent, false);
                 return new GradebookViewHolder(view);
             default:
                 //noinspection ConstantConditions
@@ -85,8 +85,8 @@ class ModDetailGradebookAdapter extends RecyclerView.Adapter<RecyclerView.ViewHo
         Pair<Integer, Integer> data = mPositionalData.get(position);
         switch (data.first) {
             case TYPE_TOTAL:
-                HeaderViewHolder h = (HeaderViewHolder) holder;
-                h.mCaption.setText(h.mView.getResources().getString(R.string.current_percentage, mValue.getGradebookPercent()*100));
+                StringViewHolder h = (StringViewHolder) holder;
+                h.mString.setText(h.mView.getResources().getString(R.string.current_percentage, mValue.getGradebookPercent()*100));
             break;
             case TYPE_GRADE:
                 int index = data.second / 1024;
@@ -118,20 +118,6 @@ class ModDetailGradebookAdapter extends RecyclerView.Adapter<RecyclerView.ViewHo
 
 
 
-    class HeaderViewHolder extends CustomViewHolder {
-        final TextView mCaption;
-
-        HeaderViewHolder(View view) {
-            super(view);
-            mCaption = view.findViewById(R.id.caption);
-        }
-
-        @Override
-        public String toString() {
-            return super.toString() + " '" + mCaption.getText() + "'";
-        }
-    }
-
 
     private class GradebookViewHolder extends RecyclerView.ViewHolder {
         private final TextView mGrade;

app/src/main/java/de/sebse/fuplanner/fragments/moddetails/ModDetailGradebookFragment.java

@@ -3,15 +3,15 @@ package de.sebse.fuplanner.fragments.moddetails;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.v4.app.Fragment;
-import android.support.v4.widget.SwipeRefreshLayout;
-import android.support.v7.widget.LinearLayoutManager;
-import android.support.v7.widget.RecyclerView;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
+import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
+import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;
 import de.sebse.fuplanner.MainActivity;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.KVV.KVV;

app/src/main/java/de/sebse/fuplanner/fragments/moddetails/ModDetailOverviewAdapter.java

@@ -1,27 +1,27 @@
 package de.sebse.fuplanner.fragments.moddetails;
 
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
-import android.support.v7.widget.RecyclerView;
 import android.util.Pair;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
-import android.widget.TextView;
 
 import com.ms.square.android.expandabletextview.ExpandableTextView;
 
 import java.util.ArrayList;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.recyclerview.widget.RecyclerView;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.KVV.types.Announcement;
 import de.sebse.fuplanner.services.KVV.types.Assignment;
 import de.sebse.fuplanner.services.KVV.types.Event;
 import de.sebse.fuplanner.services.KVV.types.Modules;
-import de.sebse.fuplanner.tools.DateUtils;
+import de.sebse.fuplanner.tools.UtilsDate;
 import de.sebse.fuplanner.tools.logging.Logger;
 import de.sebse.fuplanner.tools.ui.CustomViewHolder;
 import de.sebse.fuplanner.tools.ui.ItemViewHolder;
+import de.sebse.fuplanner.tools.ui.StringViewHolder;
 
 class ModDetailOverviewAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
     private static final int MAX_ITEMS_PER_PREVIEW = 2;
@@ -77,7 +77,7 @@ class ModDetailOverviewAdapter extends RecyclerView.Adapter<RecyclerView.ViewHol
             case TYPE_HEADER:
                 view = LayoutInflater.from(parent.getContext())
                         .inflate(R.layout.list_all_caption, parent, false);
-                return new HeaderViewHolder(view);
+                return new StringViewHolder(view);
             case TYPE_DESCRIPTION:
                 view = LayoutInflater.from(parent.getContext())
                         .inflate(R.layout.list_moddetails_description, parent, false);
@@ -111,19 +111,19 @@ class ModDetailOverviewAdapter extends RecyclerView.Adapter<RecyclerView.ViewHol
         Pair<Integer, Object> data = mPositionalData.get(position);
         switch (data.first) {
             case TYPE_HEADER:
-                HeaderViewHolder h = (HeaderViewHolder) holder;
+                StringViewHolder h = (StringViewHolder) holder;
                 switch ((Integer) data.second) {
                     case ModulePart.DESCRIPTION:
-                        h.mCaption.setText(R.string.description);
+                        h.mString.setText(R.string.description);
                         break;
                     case ModulePart.ANNOUNCEMENT:
-                        h.mCaption.setText(h.mView.getResources().getString(R.string.announcements_count, getAnnounceCount()));
+                        h.mString.setText(h.mView.getResources().getString(R.string.announcements_count, getAnnounceCount()));
                         break;
                     case ModulePart.ASSIGNMENT:
-                        h.mCaption.setText(h.mView.getResources().getString(R.string.assignments_count, getAssignmentCount()));
+                        h.mString.setText(h.mView.getResources().getString(R.string.assignments_count, getAssignmentCount()));
                         break;
                     case ModulePart.EVENT:
-                        h.mCaption.setText(h.mView.getResources().getString(R.string.upcoming_events_count, getEventsCount()));
+                        h.mString.setText(h.mView.getResources().getString(R.string.upcoming_events_count, getEventsCount()));
                         break;
                 }
                 break;
@@ -141,7 +141,7 @@ class ModDetailOverviewAdapter extends RecyclerView.Adapter<RecyclerView.ViewHol
                         Announcement announce = mValue.announcements.get(index);
                         i.mTitle.setText(announce.getTitle());
                         i.mSubLeft.setText(announce.getCreatedBy());
-                        i.mSubRight.setText(DateUtils.getModifiedDateTime(i.mView.getContext(), announce.getCreatedOn()));
+                        i.mSubRight.setText(UtilsDate.getModifiedDateTime(i.mView.getContext(), announce.getCreatedOn()));
                         i.mView.setOnClickListener(view -> {
                             if (mListener != null) mListener.gotoFragmentPart(section, index);
                         });
@@ -154,7 +154,7 @@ class ModDetailOverviewAdapter extends RecyclerView.Adapter<RecyclerView.ViewHol
                             i.mSubLeft.setText(i.mView.getResources().getText(R.string.open));
                         else
                             i.mSubLeft.setText(i.mView.getResources().getText(R.string.closed));
-                        i.mSubRight.setText(DateUtils.getModifiedDateTime(i.mView.getContext(), assignment.getDueDate()));
+                        i.mSubRight.setText(UtilsDate.getModifiedDateTime(i.mView.getContext(), assignment.getDueDate()));
                         i.mView.setOnClickListener(view -> {
                             if (mListener != null) mListener.gotoFragmentPart(section, index);
                         });
@@ -165,14 +165,14 @@ class ModDetailOverviewAdapter extends RecyclerView.Adapter<RecyclerView.ViewHol
                         i.mTitle.setText(event.getTitle());
                         i.mSubLeft.setText(event.getType());
                         String start, end;
-                        if (DateUtils.dateEquals(event.getStartDate(), System.currentTimeMillis()))
-                            start = DateUtils.getModifiedTime(i.mView.getContext(), event.getStartDate());
+                        if (UtilsDate.dateEquals(event.getStartDate(), System.currentTimeMillis()))
+                            start = UtilsDate.getModifiedTime(i.mView.getContext(), event.getStartDate());
                         else
-                            start = DateUtils.getModifiedDateTime(i.mView.getContext(), event.getStartDate());
-                        if (DateUtils.dateEquals(event.getStartDate(), event.getEndDate()))
-                            end = DateUtils.getModifiedTime(i.mView.getContext(), event.getEndDate());
+                            start = UtilsDate.getModifiedDateTime(i.mView.getContext(), event.getStartDate());
+                        if (UtilsDate.dateEquals(event.getStartDate(), event.getEndDate()))
+                            end = UtilsDate.getModifiedTime(i.mView.getContext(), event.getEndDate());
                         else
-                            end = DateUtils.getModifiedDateTime(i.mView.getContext(), event.getEndDate());
+                            end = UtilsDate.getModifiedDateTime(i.mView.getContext(), event.getEndDate());
                         i.mSubRight.setText(i.mView.getResources().getString(R.string.date_scale,
                                 start, end
                                 ));
@@ -221,19 +221,7 @@ class ModDetailOverviewAdapter extends RecyclerView.Adapter<RecyclerView.ViewHol
 
 
 
-    class HeaderViewHolder extends CustomViewHolder {
-        final TextView mCaption;
 
-        HeaderViewHolder(View view) {
-            super(view);
-            mCaption = view.findViewById(R.id.caption);
-        }
-
-        @Override
-        public String toString() {
-            return super.toString() + " '" + mCaption.getText() + "'";
-        }
-    }
 
     class DescriptionViewHolder extends CustomViewHolder {
         final ExpandableTextView mText;

app/src/main/java/de/sebse/fuplanner/fragments/moddetails/ModDetailOverviewFragment.java

@@ -3,16 +3,16 @@ package de.sebse.fuplanner.fragments.moddetails;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
-import android.support.v4.app.Fragment;
-import android.support.v4.widget.SwipeRefreshLayout;
-import android.support.v7.widget.LinearLayoutManager;
-import android.support.v7.widget.RecyclerView;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.fragment.app.Fragment;
+import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
+import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;
 import de.sebse.fuplanner.MainActivity;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.services.KVV.KVV;

app/src/main/java/de/sebse/fuplanner/fragments/moddetails/ModDetailResourceAdapter.java

@@ -0,0 +1,34 @@
+package de.sebse.fuplanner.fragments.moddetails;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import de.sebse.fuplanner.services.KVV.types.Modules;
+import de.sebse.fuplanner.services.KVV.types.Resource;
+import de.sebse.fuplanner.tools.ui.treeview.TreeNode;
+import de.sebse.fuplanner.tools.ui.treeview.TreeViewAdapter;
+import de.sebse.fuplanner.tools.ui.treeview.TreeViewBinder;
+
+class ModDetailResourceAdapter extends TreeViewAdapter {
+    private Modules.Module mValue;
+    public ModDetailResourceAdapter(List<? extends TreeViewBinder> viewBinders) {
+        super(viewBinders);
+        mValue = null;
+    }
+
+    public void setModule(Modules.Module module) {
+        mValue = module;
+        this.setModule();
+    }
+
+    public void setModule() {
+        if (mValue == null || mValue.resources == null) {
+            return;
+        }
+        List<TreeNode> nodes = new ArrayList<>();
+        for (Resource res: mValue.resources) {
+            nodes.add(res.getTreeNode());
+        }
+        refresh(nodes);
+    }
+}

app/src/main/java/de/sebse/fuplanner/fragments/moddetails/ModDetailResourceFragment.java

@@ -0,0 +1,344 @@
+package de.sebse.fuplanner.fragments.moddetails;
+
+
+import android.Manifest;
+import android.app.AlertDialog;
+import android.content.Context;
+import android.content.Intent;
+import android.content.pm.PackageManager;
+import android.net.Uri;
+import android.os.Bundle;
+import android.os.Environment;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ImageView;
+
+import java.io.File;
+import java.util.ArrayList;
+import java.util.Arrays;
+
+import androidx.annotation.NonNull;
+import androidx.core.app.ActivityCompat;
+import androidx.fragment.app.Fragment;
+import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
+import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;
+import de.sebse.fuplanner.MainActivity;
+import de.sebse.fuplanner.R;
+import de.sebse.fuplanner.services.KVV.KVV;
+import de.sebse.fuplanner.services.KVV.types.Modules;
+import de.sebse.fuplanner.services.KVV.types.Resource;
+import de.sebse.fuplanner.tools.MainActivityListener;
+import de.sebse.fuplanner.tools.Regex;
+import de.sebse.fuplanner.tools.UtilsDate;
+import de.sebse.fuplanner.tools.logging.Logger;
+import de.sebse.fuplanner.tools.ui.treeview.DirectoryNodeBinder;
+import de.sebse.fuplanner.tools.ui.treeview.FileNodeBinder;
+import de.sebse.fuplanner.tools.ui.treeview.TreeNode;
+import de.sebse.fuplanner.tools.ui.treeview.TreeViewAdapter;
+
+import static androidx.core.content.ContextCompat.checkSelfPermission;
+
+/**
+ * A simple {@link Fragment} subclass.
+ * Use the {@link ModDetailResourceFragment#newInstance} factory method to
+ * create an instance of this fragment.
+ */
+public class ModDetailResourceFragment extends Fragment {
+    private static final String ARG_POSITION = "itemPosition";
+
+    private String mItemPos;
+    private final Logger log = new Logger(this);
+    private ModDetailResourceAdapter adapter;
+    private SwipeRefreshLayout swipeLayout;
+    private MainActivityListener context;
+    private RequestedDownload requestedDownload;
+
+
+    public ModDetailResourceFragment() {
+        // Required empty public constructor
+    }
+
+    /**
+     * Use this factory method to create a new instance of
+     * this fragment using the provided parameters.
+     *
+     * @param itemPosition Item position in module list.
+     * @return A new instance of fragment ModDetailAnnounceFragment.
+     */
+    public static ModDetailResourceFragment newInstance(String itemPosition) {
+        ModDetailResourceFragment fragment = new ModDetailResourceFragment();
+        Bundle args = new Bundle();
+        args.putString(ARG_POSITION, itemPosition);
+        fragment.setArguments(args);
+        return fragment;
+    }
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        if (getArguments() != null) {
+            mItemPos = getArguments().getString(ARG_POSITION);
+        }
+    }
+
+    @Override
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container,
+                             Bundle savedInstanceState) {
+        // Inflate the layout for this fragment
+        View view = inflater.inflate(R.layout.fragment_recycler_view, container, false);
+        // Set the adapter
+        Context context = view.getContext();
+        RecyclerView recyclerView = view.findViewById(R.id.list);
+        recyclerView.setLayoutManager(new LinearLayoutManager(context));
+
+        adapter = new ModDetailResourceAdapter(Arrays.asList(new FileNodeBinder(), new DirectoryNodeBinder()));
+        adapter.setOnTreeNodeListener(new TreeViewAdapter.OnTreeNodeListener() {
+            @Override
+            public boolean onClick(TreeNode node, RecyclerView.ViewHolder holder) {
+                if (!node.isLeaf()) {
+                    // Update and toggle the node.
+                    onToggle(!node.isExpand(), holder);
+                } else if(node.getContent() instanceof Resource.File) { // if leaf is file
+                    KVV kvv = ModDetailResourceFragment.this.context.getKVV();
+                    kvv.getModule(mItemPos, (Modules.Module module) -> {
+                        if (getContext() == null)
+                            return;
+                        AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(getContext());
+                        Resource.File file = (Resource.File) node.getContent();
+                        String folderName = "FU-"+module.title.replaceAll("[:*<>|/\"\\\\]", "-");
+                        File f = new File(Environment.getExternalStoragePublicDirectory(
+                                Environment.DIRECTORY_DOWNLOADS)+"/"+folderName+"/"+file.getTitle());
+                        alertDialogBuilder
+                                .setTitle(file.getTitle())
+                                .setMessage(
+                                        getResources().getString(R.string.creator_name, file.getAuthor()) + "\n" +
+                                        getResources().getString(R.string.last_modified_on, UtilsDate.getModifiedDateTime(context, file.getModifiedDate()))
+                                )
+                                .setCancelable(true)
+                                .setNeutralButton(R.string.close, (dialog, id) -> dialog.cancel())
+                                .setPositiveButton(R.string.download, (dialog, id) -> download(file, folderName, true));
+                        // if already downloaded, show open button
+                        if (f.exists()) {
+                            alertDialogBuilder
+                                    .setNegativeButton(R.string.openFile, (dialog, id) -> download(file, folderName, false));
+                        }
+                        AlertDialog alertDialog = alertDialogBuilder.create();
+                        alertDialog.show();
+
+                    }, log::e);
+                }
+                return false;
+            }
+
+            @Override
+            public void onToggle(boolean isExpand, RecyclerView.ViewHolder holder) {
+                DirectoryNodeBinder.ViewHolder dirViewHolder = (DirectoryNodeBinder.ViewHolder) holder;
+                final ImageView ivArrow = dirViewHolder.getIvArrow();
+                int rotateDegree = isExpand ? 90 : -90;
+                ivArrow.animate().rotationBy(rotateDegree).start();
+            }
+        });
+
+        recyclerView.setAdapter(adapter);
+
+        // Getting SwipeContainerLayout
+        swipeLayout = view.findViewById(R.id.swipe_container);
+        // Adding Listener
+        swipeLayout.setOnRefreshListener(() -> refresh(true));
+        refresh(false);
+
+        return view;
+    }
+
+    private void download(Resource.File file, String folderName, boolean downloadNew){
+        if (getActivity() == null) {
+            showDownloadError();
+            return;
+        }
+        if (checkSelfPermission(getActivity(), android.Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
+            // Access granted
+            downloadOrOpen(file, folderName, downloadNew);
+        } else {
+            this.requestedDownload = new RequestedDownload(file, folderName, downloadNew);
+            ActivityCompat.requestPermissions(ModDetailResourceFragment.super.getActivity(),
+                    new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
+                    1);
+        }
+    }
+
+    private void downloadOrOpen(Resource.File file, String folderName, boolean downloadNew) {
+        KVV kvv = this.context.getKVV();
+        if(isExternalStorageWritable()){
+            kvv.getResourceFile(success1 -> {
+                // Downloading file failed
+                if (success1.equals("")){
+                    showDownloadError();
+                }else {
+                    if (Regex.has("^http", success1)){
+                        Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(success1));
+                        startActivity(intent);
+                    }
+                    else {
+                        fileOpen(new File(success1));
+                    }
+
+                }
+            }, log::e, file.getTitle(), file.getUrl(), folderName, downloadNew);
+        }
+    }
+
+    private void showDownloadError() {
+        AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(getContext());
+        alertDialogBuilder
+                .setTitle(R.string.ErrorFileDownload)
+                .setMessage(
+                        R.string.ErrorFileDownloadText
+                )
+                .setCancelable(true)
+                .setNeutralButton(R.string.close, (dialog, id) -> dialog.cancel());
+        AlertDialog alertDialog = alertDialogBuilder.create();
+        alertDialog.show();
+    }
+
+    @Override
+    public void onAttach(Context context) {
+        super.onAttach(context);
+        if (context instanceof MainActivityListener) {
+            this.context = ((MainActivityListener) context);
+            this.context.addRequestPermissionsResultListener((requestCode, permissions, grantResults) -> {
+                if (requestedDownload == null) {
+                    log.d("No request");
+                    return;
+                }
+                if (getActivity() == null) {
+                    showDownloadError();
+                    return;
+                }
+                ArrayList<Integer> intList = new ArrayList<>();
+                for (int i : grantResults)
+                {
+                    intList.add(i);
+                }
+                log.d(requestCode, Arrays.asList(permissions), intList);
+                int pos = Arrays.asList(permissions).indexOf("android.permission.WRITE_EXTERNAL_STORAGE");
+                if (pos != -1) {
+                    if (grantResults[pos] != -1) {
+                        downloadOrOpen(requestedDownload.file, requestedDownload.folderName, requestedDownload.downloadNew);
+                    } else {
+                        log.d(requestedDownload, pos, grantResults[pos]);
+                        showDownloadError();
+                    }
+                    requestedDownload = null;
+                }
+            }, "ModDetailResourceFragment");
+        } else
+            throw new RuntimeException(context.toString() + " must implement MainActivityListener");
+    }
+
+    @Override
+    public void onDetach() {
+        super.onDetach();
+        this.context.removeRequestPermissionsResultListener("ModDetailResourceFragment");
+    }
+
+    /* Checks if external storage is available for read and write */
+    private boolean isExternalStorageWritable() {
+        String state = Environment.getExternalStorageState();
+        if (Environment.MEDIA_MOUNTED.equals(state)) {
+            return true;
+        }
+        log.e("File system: Writing not possible");
+        return false;
+    }
+
+    private void fileOpen(File url){
+        Uri uri = Uri.fromFile(url);
+
+        Intent intent = new Intent();//Intent.ACTION_VIEW
+        // Check what kind of file you are trying to open, by comparing the url with extensions.
+        // When the if condition is matched, plugin sets the correct intent (mime) type,
+        // so Android knew what application to use to open the file
+        if (url.toString().contains(".doc") || url.toString().contains(".docx")) {
+            // Word document
+            intent.setDataAndType(uri, "application/msword");
+        } else if(url.toString().contains(".pdf")) {
+            // PDF file
+            intent.setDataAndType(uri, "application/pdf");
+        } else if(url.toString().contains(".ppt") || url.toString().contains(".pptx")) {
+            // Powerpoint file
+            intent.setDataAndType(uri, "application/vnd.ms-powerpoint");
+        } else if(url.toString().contains(".xls") || url.toString().contains(".xlsx")) {
+            // Excel file
+            intent.setDataAndType(uri, "application/vnd.ms-excel");
+        } else if(url.toString().contains(".zip") || url.toString().contains(".rar")) {
+            // ZIP file
+            intent.setDataAndType(uri, "application/zip");
+        } else if(url.toString().contains(".rtf")) {
+            // RTF file
+            intent.setDataAndType(uri, "application/rtf");
+        } else if(url.toString().contains(".wav") || url.toString().contains(".mp3")) {
+            // WAV audio file
+            intent.setDataAndType(uri, "audio/x-wav");
+        } else if(url.toString().contains(".gif")) {
+            // GIF file
+            intent.setDataAndType(uri, "image/gif");
+        } else if(url.toString().contains(".jpg") || url.toString().contains(".jpeg") || url.toString().contains(".png")) {
+            // JPG file
+            intent.setDataAndType(uri, "image/jpeg");
+        } else if(url.toString().contains(".txt")) {
+            // Text file
+            intent.setDataAndType(uri, "text/plain");
+        } else if(url.toString().contains(".3gp") || url.toString().contains(".mpg") || url.toString().contains(".mpeg") || url.toString().contains(".mpe") || url.toString().contains(".mp4") || url.toString().contains(".avi")) {
+            // Video files
+            intent.setDataAndType(uri, "video/*");
+        } else {
+            //if you want you can also define the intent type for any other file
+
+            //additionally use else clause below, to manage other unknown extensions
+            //in this case, Android will show all applications installed on the device
+            //so you can choose which application to use
+            intent.setDataAndType(uri, "*/*");
+        }
+
+        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
+        startActivity(intent);
+
+    }
+
+    private void refresh(boolean forceRefresh) {
+        if (getActivity() != null) {
+            KVV kvv = ((MainActivity) getActivity()).getKVV();
+            kvv.getModule(mItemPos, (Modules.Module module) -> {
+                adapter.setModule(module);
+                kvv.getModuleResources(module, success1 -> {
+                    adapter.setModule();
+                    swipeLayout.setRefreshing(false);
+                }, error -> {
+                    swipeLayout.setRefreshing(false);
+                    log.e(error);
+                }, forceRefresh);
+            }, error -> {
+                swipeLayout.setRefreshing(false);
+                log.e(error);
+            }, forceRefresh);
+        }
+    }
+
+
+
+
+
+    private class RequestedDownload {
+        Resource.File file;
+        String folderName;
+        boolean downloadNew;
+
+        RequestedDownload(Resource.File file, String folderName, boolean downloadNew) {
+            this.file = file;
+            this.folderName = folderName;
+            this.downloadNew = downloadNew;
+        }
+    }
+}

app/src/main/java/de/sebse/fuplanner/fragments/moddetails/ModulePart.java

@@ -7,7 +7,8 @@ class ModulePart {
     static final int ASSIGNMENT = 3;
     static final int EVENT = 4;
     static final int GRADEBOOK = 5;
-    private static final int[] pages = new int[]{OVERVIEW, ANNOUNCEMENT, ASSIGNMENT, EVENT, GRADEBOOK};
+    static final int RESOURCES = 6;
+    private static final int[] pages = new int[]{OVERVIEW, ANNOUNCEMENT, ASSIGNMENT, EVENT, GRADEBOOK, RESOURCES};
 
     static int getPageCount() {
         return pages.length;

app/src/main/java/de/sebse/fuplanner/services/Canteen/CanteenBrowser.java

@@ -13,7 +13,7 @@ import de.sebse.fuplanner.services.Canteen.types.Canteen;
 import de.sebse.fuplanner.services.Canteen.types.Canteens;
 import de.sebse.fuplanner.services.Canteen.types.Day;
 import de.sebse.fuplanner.tools.AsyncQueue;
-import de.sebse.fuplanner.tools.MainAcitivityListener;
+import de.sebse.fuplanner.tools.MainActivityListener;
 import de.sebse.fuplanner.tools.network.HTTPService;
 import de.sebse.fuplanner.tools.network.NetworkCallback;
 import de.sebse.fuplanner.tools.network.NetworkError;
@@ -23,12 +23,12 @@ public class CanteenBrowser extends HTTPService {
     private Canteens canteens;
     private final AsyncQueue queue = new AsyncQueue();
     private final Context context;
-    private MainAcitivityListener mListener;
+    private MainActivityListener mListener;
 
     public CanteenBrowser(Context context) {
         super(context);
         this.context = context;
-        if (context instanceof MainAcitivityListener)
+        if (context instanceof MainActivityListener)
             mListener = (MainActivity) context;
         else
             throw new RuntimeException(context.toString() + "must implement MainActivityListener");
@@ -65,7 +65,7 @@ public class CanteenBrowser extends HTTPService {
     }
 
     private void upgradeCanteens(final NetworkCallback<Canteens> callback, final NetworkErrorCallback errorCallback) {
-        get("https://openmensa.org/api/v2/canteens", null, response -> {
+        get("https://openmensa.org/api/v2/canteens?near[lat]=52.449743&near[lng]=13.282245&near[dist]=7", null, response -> {
             String body = response.getParsed();
             if (body == null) {
                 errorCallback.onError(new NetworkError(201101, 403, "No canteen list retrieved!"));
@@ -192,9 +192,9 @@ public class CanteenBrowser extends HTTPService {
                     double priceEmply = 0;
                     double priceOther = 0;
                     if (prices != null) {
-                        priceStdnt = prices.getDouble("students");
-                        priceEmply = prices.getDouble("employees");
-                        priceOther = prices.getDouble("others");
+                        priceOther = prices.optDouble("others", -1);
+                        priceEmply = prices.optDouble("employees", priceOther);
+                        priceStdnt = prices.optDouble("students", priceEmply);
                     }
                     JSONArray noteArray = meal.getJSONArray("notes");
                     String[] notes = new String[noteArray.length()];
@@ -206,6 +206,7 @@ public class CanteenBrowser extends HTTPService {
                 }
             } catch (JSONException e) {
                 e.printStackTrace();
+                log.d(body);
                 errorCallback.onError(new NetworkError(201302, 403, "Cannot parse meal list!"));
                 return;
             }
@@ -224,17 +225,14 @@ public class CanteenBrowser extends HTTPService {
     private<T> NetworkCallback<T> saveOnCallback(NetworkCallback<T> callback, boolean forceRefresh){
         return (success -> {
             if (forceRefresh)
-                mListener.refreshFailed(false);
+                mListener.onRefreshCompleted(false);
             callback.onResponse(success);
         });
     }
 
     private NetworkErrorCallback errorOnCallback(NetworkErrorCallback errorCallback){
         return (error -> {
-            if (error.getHttpStatus() == 401 || error.getHttpStatus() == 403)
-                mListener.loginTokenInvalid(false);
-            else
-                mListener.refreshFailed(true);
+            mListener.onRefreshCompleted(true);
             errorCallback.onError(error);
         });
     }

app/src/main/java/de/sebse/fuplanner/services/Canteen/types/Canteen.java

@@ -1,6 +1,6 @@
 package de.sebse.fuplanner.services.Canteen.types;
 
-import android.support.annotation.NonNull;
+import androidx.annotation.NonNull;
 
 import java.io.Serializable;
 import java.util.Calendar;
@@ -50,6 +50,17 @@ public class Canteen implements Serializable, Iterable<Day> {
         }
     }
 
+    public void cleanUpDays() {
+        SortedListDay newList = new SortedListDay();
+        Calendar cal = Calendar.getInstance();
+        for (Day day : list) {
+            if (Canteen.calendarToKey(day.getCalendar()).compareTo(Canteen.calendarToKey(cal)) >= 0) {
+                newList.add(day);
+            }
+        }
+        list = newList;
+    }
+
     public int size() {
         return this.list.size();
     }

app/src/main/java/de/sebse/fuplanner/services/Canteen/types/Canteens.java

@@ -1,7 +1,7 @@
 package de.sebse.fuplanner.services.Canteen.types;
 
 import android.content.Context;
-import android.support.annotation.NonNull;
+import androidx.annotation.NonNull;
 
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
@@ -12,7 +12,7 @@ import java.io.Serializable;
 import java.util.Iterator;
 
 public class Canteens implements Serializable, Iterable<Canteen> {
-    public static final int[] availableCanteens = {27, 28, 42};
+    public static final int[] availableCanteens = {27, 42, 813, 810, 811, 812, 821};
     private static final String FILE_NAME = "CanteensSaving";
     private SortedListCanteen list = new SortedListCanteen();
 
@@ -68,7 +68,7 @@ public class Canteens implements Serializable, Iterable<Canteen> {
 
             @Override
             public void remove() {
-                throw new UnsupportedOperationException("You are not alloed to remove an entry!");
+                throw new UnsupportedOperationException("You are not allowed to remove an entry!");
             }
         };
     }

app/src/main/java/de/sebse/fuplanner/services/Canteen/types/Day.java

@@ -1,6 +1,6 @@
 package de.sebse.fuplanner.services.Canteen.types;
 
-import android.support.annotation.NonNull;
+import androidx.annotation.NonNull;
 
 import java.io.Serializable;
 import java.util.Calendar;

app/src/main/java/de/sebse/fuplanner/services/Canteen/types/Meal.java

@@ -6,14 +6,14 @@ import java.util.Collections;
 import java.util.List;
 
 public class Meal implements Serializable {
-    public static final int LIGHT_NONE = 0;
-    public static final int LIGHT_GREEN = 1;
-    public static final int LIGHT_YELLOW = 2;
-    public static final int LIGHT_RED = 3;
-    public static final int VEGAN_NONE = 0;
-    public static final int VEGAN_VEGETERIAN = 1;
+    private static final int LIGHT_NONE = 0;
+    private static final int LIGHT_GREEN = 1;
+    private static final int LIGHT_YELLOW = 2;
+    private static final int LIGHT_RED = 3;
+    private static final int VEGAN_NONE = 0;
+    public static final int VEGAN_VEGETARIAN = 1;
     public static final int VEGAN_VEGAN = 2;
-    public static final int CERT_NONE = 0b0000;
+    private static final int CERT_NONE = 0b0000;
     public static final int CERT_BIO =  0b0001;
     public static final int CERT_MSC =  0b0010;
 
@@ -42,7 +42,7 @@ public class Meal implements Serializable {
         for (String note : notes) {
             switch (note.toLowerCase()) {
                 case "vegetarisch":
-                    vegan = VEGAN_VEGETERIAN;
+                    vegan = VEGAN_VEGETARIAN;
                     break;
                 case "vegan":
                     vegan = VEGAN_VEGAN;

app/src/main/java/de/sebse/fuplanner/services/GoogleAuth/GoogleAuth.java

@@ -2,8 +2,6 @@ package de.sebse.fuplanner.services.GoogleAuth;
 
 import android.content.Intent;
 import android.content.IntentSender;
-import android.support.annotation.Nullable;
-import android.support.v4.app.FragmentActivity;
 import android.util.Log;
 import android.widget.Toast;
 
@@ -17,6 +15,9 @@ import com.google.android.gms.common.api.ApiException;
 import com.google.android.gms.common.api.CommonStatusCodes;
 import com.google.android.gms.common.api.ResolvableApiException;
 
+import androidx.annotation.Nullable;
+import androidx.fragment.app.FragmentActivity;
+
 import static android.app.Activity.RESULT_OK;
 
 /**

app/src/main/java/de/sebse/fuplanner/services/KVV/KVV.java

@@ -1,16 +1,17 @@
 package de.sebse.fuplanner.services.KVV;
 
 import android.content.Context;
-import android.support.annotation.NonNull;
 import android.util.Pair;
 
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.HashMap;
 
+import androidx.annotation.NonNull;
 import de.sebse.fuplanner.services.KVV.types.LoginToken;
 import de.sebse.fuplanner.services.KVV.types.Modules;
-import de.sebse.fuplanner.tools.MainAcitivityListener;
+import de.sebse.fuplanner.tools.MainActivityListener;
+import de.sebse.fuplanner.tools.logging.Logger;
 import de.sebse.fuplanner.tools.network.NetworkCallback;
 import de.sebse.fuplanner.tools.network.NetworkErrorCallback;
 
@@ -24,14 +25,20 @@ public class KVV {
     private boolean isLoginPending = true;
     private final ArrayList<LastTokenCallback> updatingList;
     private final HashMap<String, Object> addons = new HashMap<>();
-    private final MainAcitivityListener mListener;
+    private final MainActivityListener mListener;
+    private Logger log = new Logger(this);
 
     public KVV(Context context) {
-        mListener = (MainAcitivityListener) context;
+        mListener = (MainActivityListener) context;
         this.context = context;
         this.updatingList = new ArrayList<>();
     }
 
+    public boolean isLoggedIn() {
+        log.d(this.lastToken, new KVVLogin(this.context).easyLogin());
+        return this.lastToken != null;
+    }
+
     public LoginToken easyLogin() {
         KVVLogin login = new KVVLogin(this.context);
         lastToken = login.easyLogin();
@@ -137,6 +144,18 @@ public class KVV {
         getModulePart(modules -> modules.getResources(module, saveOnCallback(modules, callback, forceRefresh), errorOnCallback(error), forceRefresh));
     }
 
+    public void getResourceFile(final NetworkCallback<String> callback, final NetworkErrorCallback error, String filename, String url, String moduleName, boolean downloadNew){
+        getModulePart(modules -> modules.getResourceFile(callback, errorOnCallback(error),filename, url, moduleName, downloadNew));
+    }
+
+    public void testLogin(BooleanFunction callback) {
+        getLastToken(lastToken -> {
+            TestLogin.testLogin(context, lastToken, success -> callback.apply(true), error -> callback.apply(false));
+        });
+    }
+
+
+
 
 
     private void getModulePart(ModListFunction func) {
@@ -158,7 +177,7 @@ public class KVV {
                 e.printStackTrace();
             }
             if (forceRefresh)
-                mListener.refreshFailed(false);
+                mListener.onRefreshCompleted(false);
             callback.onResponse(success);
         });
     }
@@ -166,9 +185,9 @@ public class KVV {
     private NetworkErrorCallback errorOnCallback(NetworkErrorCallback errorCallback){
         return (error -> {
             if (error.getHttpStatus() == 401 || error.getHttpStatus() == 403)
-                mListener.loginTokenInvalid(false);
+                mListener.loginTokenInvalid(true);
             else
-                mListener.refreshFailed(true);
+                mListener.onRefreshCompleted(true);
             errorCallback.onError(error);
         });
     }
@@ -178,6 +197,11 @@ public class KVV {
         void apply(KVVModuleList mod);
     }
 
+    @FunctionalInterface
+    public interface BooleanFunction {
+        void apply(boolean isSuccess);
+    }
+
     private void getLastToken(LastTokenCallback lastTokenCallback) {
         if (this.isLoginPending) {
             this.updatingList.add(lastTokenCallback);

app/src/main/java/de/sebse/fuplanner/services/KVV/KVVLogin.java

@@ -2,9 +2,6 @@ package de.sebse.fuplanner.services.KVV;
 
 import android.content.Context;
 
-import org.json.JSONException;
-import org.json.JSONObject;
-
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.regex.Matcher;
@@ -16,17 +13,17 @@ import de.sebse.fuplanner.tools.network.NetworkCallback;
 import de.sebse.fuplanner.tools.network.NetworkError;
 import de.sebse.fuplanner.tools.network.NetworkErrorCallback;
 
+import static de.sebse.fuplanner.services.KVV.TestLogin.testLogin;
+
 /**
  * Created by sebastian on 24.10.17.
  */
 
 class KVVLogin extends HTTPService {
-    private final Context mContext;
     private LoginToken loginToken;
 
     KVVLogin(Context context) {
-        super(context, false);
-        this.mContext = context;
+        super(context);
         try {
             this.loginToken = LoginToken.load(context);
         } catch (IOException e) {
@@ -36,14 +33,14 @@ class KVVLogin extends HTTPService {
         }
     }
 
-    public LoginToken easyLogin() {
+    LoginToken easyLogin() {
         return this.loginToken;
     }
 
-    public void login(String username, String password, NetworkCallback<LoginToken> callback, NetworkErrorCallback errorCallback) {
+    void login(String username, String password, NetworkCallback<LoginToken> callback, NetworkErrorCallback errorCallback) {
         if (this.loginToken != null) {
             if (this.loginToken.getUsername().equals(username)) {
-                testLogin(this.loginToken, success -> callback.onResponse(this.loginToken), error -> {
+                testLogin(getContext(), this.loginToken, success -> callback.onResponse(this.loginToken), error -> {
                     this.loginToken = null;
                     login(username, password, callback, errorCallback);
                 });
@@ -54,19 +51,19 @@ class KVVLogin extends HTTPService {
         } else {
             doLogin(username, password, token -> {
                 this.loginToken = token;
-                testLogin(this.loginToken, success -> callback.onResponse(this.loginToken), errorCallback);
+                testLogin(getContext(), this.loginToken, success -> callback.onResponse(this.loginToken), errorCallback);
             }, errorCallback);
         }
     }
 
-    public void deleteOffline() {
+    void deleteOffline() {
         if (this.loginToken != null)
-            this.loginToken.delete(mContext);
+            this.loginToken.delete(getContext());
     }
 
-    public void saveOffline() throws IOException {
+    void saveOffline() throws IOException {
         if (this.loginToken != null)
-            this.loginToken.save(mContext);
+            this.loginToken.save(getContext());
     }
 
 
@@ -92,21 +89,6 @@ class KVVLogin extends HTTPService {
         }, error);
     }
 
-    private void testLogin(LoginToken loginToken, NetworkCallback<LoginToken> callback, NetworkErrorCallback errorCallback) {
-        get(String.format("https://kvv.imp.fu-berlin.de/direct/profile/%s.json", loginToken.getUsername()), loginToken.getCookies(), response -> {
-            String body = response.getParsed();
-            try {
-                JSONObject json = new JSONObject(body);
-                String displayName = json.getString("displayName");
-                String email = json.getString("email");
-                loginToken.setAdditionals(displayName, email);
-                callback.onResponse(loginToken);
-            } catch (JSONException e) {
-                errorCallback.onError(new NetworkError(100201, 403, "Cannot parse profile!"));
-            }
-        }, error -> errorCallback.onError(new NetworkError(100200, error.networkResponse.statusCode, "Testing login failed!")));
-    }
-
     /*
     GET https://kvv.imp.fu-berlin.de/portal/login
     -> JSESSIONID 5c10406f-588c-4c16-96e9-c80d115417de.tomcat1
@@ -233,10 +215,16 @@ class KVVLogin extends HTTPService {
         cookies.put("ROUTEID", ROUTEID);
         cookies.put("_idp_session", _idp_session);
         get("https://identity.fu-berlin.de/idp-fub/profile/SAML2/Redirect/SSO", cookies, response -> {
+            String body = response.getParsed();
+            if (body == null) {
+                errorCallback.onError(new NetworkError(100143, -1, "Error on getting SAML response!"));
+                return;
+            }
+            
             HashMap<String, String> object = new HashMap<>();
 
             Pattern pattern = Pattern.compile("ss&#x3a;mem&#x3a;([0-9a-f]+)");
-            Matcher matcher = pattern.matcher(response.getParsed());
+            Matcher matcher = pattern.matcher(body);
             if (!matcher.find()) {
                 errorCallback.onError(new NetworkError(100142, -1, "Error on getting SAML response!"));
                 return;
@@ -244,7 +232,7 @@ class KVVLogin extends HTTPService {
             object.put("RelayState", "ss:mem:"+matcher.group(1));
 
             pattern = Pattern.compile("name=\"SAMLResponse\" value=\"([0-9a-zA-Z+]+=*)");
-            matcher = pattern.matcher(response.getParsed());
+            matcher = pattern.matcher(body);
             if (!matcher.find()) {
                 errorCallback.onError(new NetworkError(100141, -1, "Error on getting SAML response!"));
                 return;

app/src/main/java/de/sebse/fuplanner/services/KVV/KVVModuleList.java

@@ -1,14 +1,16 @@
 package de.sebse.fuplanner.services.KVV;
 
 import android.content.Context;
+import android.os.Environment;
+import android.text.Html;
 import android.util.Pair;
 
-import net.htmlparser.jericho.Source;
-
 import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;
 
+import java.io.File;
+import java.io.FileOutputStream;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.HashSet;
@@ -18,20 +20,23 @@ import java.util.regex.MatchResult;
 
 import de.sebse.fuplanner.services.KVV.types.Announcement;
 import de.sebse.fuplanner.services.KVV.types.Assignment;
+import de.sebse.fuplanner.services.KVV.types.AssignmentList;
 import de.sebse.fuplanner.services.KVV.types.Event;
+import de.sebse.fuplanner.services.KVV.types.EventList;
 import de.sebse.fuplanner.services.KVV.types.Gradebook;
 import de.sebse.fuplanner.services.KVV.types.Lecturer;
 import de.sebse.fuplanner.services.KVV.types.LoginToken;
 import de.sebse.fuplanner.services.KVV.types.Modules;
-import de.sebse.fuplanner.services.KVV.types.AssignmentList;
 import de.sebse.fuplanner.services.KVV.types.Resource;
 import de.sebse.fuplanner.tools.AsyncQueue;
-import de.sebse.fuplanner.services.KVV.types.EventList;
 import de.sebse.fuplanner.tools.Regex;
 import de.sebse.fuplanner.tools.network.HTTPService;
 import de.sebse.fuplanner.tools.network.NetworkCallback;
 import de.sebse.fuplanner.tools.network.NetworkError;
 import de.sebse.fuplanner.tools.network.NetworkErrorCallback;
+import de.sebse.fuplanner.tools.network.Result;
+
+import static de.sebse.fuplanner.services.KVV.TestLogin.testLogin;
 
 /**
  * Created by sebastian on 29.10.17.
@@ -59,7 +64,7 @@ class KVVModuleList extends HTTPService {
 
 
 
-    public void getModuleList(final NetworkCallback<Modules> callback, final NetworkErrorCallback errorCallback, boolean forceRefresh) {
+    void getModuleList(final NetworkCallback<Modules> callback, final NetworkErrorCallback errorCallback, boolean forceRefresh) {
         queueModuleDetails.add("list", () -> {
             if (this.moduleList != null && !forceRefresh) {
                 callback.onResponse(this.moduleList);
@@ -108,7 +113,7 @@ class KVVModuleList extends HTTPService {
                     }
                     String type = site.getJSONObject("props").getString("kvv_coursetype");
                     String description = site.getString("description");
-                    description = new Source(description).getRenderer().toString();
+                    description = String.valueOf(Html.fromHtml(description));
                     String id = site.getString("id");
                     modules.addModule(semester, lvNumbers, title, lecturers, type, description, id);
                 }
@@ -123,24 +128,26 @@ class KVVModuleList extends HTTPService {
             }
             // Empty module *may be* because token is invalid -> check
             if (modules.size() == 0)
-                testLogin(token, token -> callback.onResponse(modules), errorCallback);
+                testLogin(getContext(), token, token -> callback.onResponse(modules), errorCallback);
             else
                 callback.onResponse(modules);
         }, error -> errorCallback.onError(new NetworkError(101104, error.networkResponse.statusCode, "Cannot get module list!")));
     }
 
-    public void deleteModulesOffline(Context context) {
+    void deleteModulesOffline(Context context) {
         if (this.moduleList != null)
             this.moduleList.delete(context);
     }
 
-    public void saveModulesOffline(Context context) throws IOException {
+    void saveModulesOffline(Context context) throws IOException {
         if (this.moduleList != null)
             this.moduleList.save(context);
     }
 
-    public void getModule(String id, final NetworkCallback<Modules.Module> callback, final NetworkErrorCallback errorCallback, boolean forceRefresh) {
-        this.getModuleList(success -> callback.onResponse(success.get(id)), errorCallback, forceRefresh);
+    void getModule(String id, final NetworkCallback<Modules.Module> callback, final NetworkErrorCallback errorCallback, boolean forceRefresh) {
+        this.getModuleList(success -> {
+            callback.onResponse(success.get(id));
+        }, errorCallback, forceRefresh);
     }
 
 
@@ -148,7 +155,7 @@ class KVVModuleList extends HTTPService {
 
 
 
-    public void getModuleDetails(Modules.Module module, final NetworkCallback<Pair<Modules.Module, Boolean>> callback, final NetworkErrorCallback errorCallback, boolean forceRefresh) {
+    void getModuleDetails(Modules.Module module, final NetworkCallback<Pair<Modules.Module, Boolean>> callback, final NetworkErrorCallback errorCallback, boolean forceRefresh) {
         AtomicInteger returns = new AtomicInteger(0);
         AtomicReference<NetworkError> lastError = new AtomicReference<>(null);
         final AtomicInteger items = new AtomicInteger(0);
@@ -188,7 +195,7 @@ class KVVModuleList extends HTTPService {
 
 
 
-    public void getAnnouncements(Modules.Module module, final NetworkCallback<Modules.Module> callback, final NetworkErrorCallback errorCallback, boolean forceRefresh) {
+    void getAnnouncements(Modules.Module module, final NetworkCallback<Modules.Module> callback, final NetworkErrorCallback errorCallback, boolean forceRefresh) {
         queueModuleDetails.add(module.getID(), () -> {
             if (module.announcements != null && !forceRefresh) {
                 callback.onResponse(module);
@@ -224,13 +231,13 @@ class KVVModuleList extends HTTPService {
                     String id = site.getString("announcementId");
                     String title = site.getString("title");
                     String text = site.getString("body");
-                    text = new Source(text).getRenderer().toString();
+                    text = String.valueOf(Html.fromHtml(text));
                     String createdBy = site.getString("createdByDisplayName");
                     long createdOn = site.getLong("createdOn");
 
 
 
-                    //PDFs links rausziehen
+                    // Extract attachment links
                     JSONArray attachments = site.getJSONArray("attachments");
                     ArrayList<String> urls = new ArrayList<>();
                     for (int j =0; j<attachments.length(); j++){
@@ -247,7 +254,7 @@ class KVVModuleList extends HTTPService {
             }
             // Empty announcements *may be* because token is invalid -> check
             if (announcements.size() == 0)
-                testLogin(token, token -> callback.onResponse(announcements), errorCallback);
+                testLogin(getContext(), token, token -> callback.onResponse(announcements), errorCallback);
             else
                 callback.onResponse(announcements);
         }, error -> errorCallback.onError(new NetworkError(101203, error.networkResponse.statusCode, "Cannot get announcements!")));
@@ -257,7 +264,7 @@ class KVVModuleList extends HTTPService {
 
 
 
-    public void getAssignments(Modules.Module module, final NetworkCallback<Modules.Module> callback, final NetworkErrorCallback errorCallback, boolean forceRefresh) {
+    void getAssignments(Modules.Module module, final NetworkCallback<Modules.Module> callback, final NetworkErrorCallback errorCallback, boolean forceRefresh) {
         queueModuleDetails.add(module.getID(), () -> {
             if (module.assignments != null && !forceRefresh) {
                 callback.onResponse(module);
@@ -293,7 +300,7 @@ class KVVModuleList extends HTTPService {
                     String id = site.getString("id");
                     String title = site.getString("title");
                     String instructions = site.getString("instructions");
-                    instructions = new Source(instructions).getRenderer().toString();
+                    instructions = String.valueOf(Html.fromHtml(instructions));
                     long dueTime = site.getJSONObject("dueTime").getLong("time");
                     String gradebookItemName = site.optString("gradebookItemName", null);
                     String gradeScale = site.getString("gradeScale");
@@ -311,7 +318,7 @@ class KVVModuleList extends HTTPService {
             }
             // Empty assignments *may be* because token is invalid -> check
             if (assignments.size() == 0)
-                testLogin(token, token -> callback.onResponse(assignments), errorCallback);
+                testLogin(getContext(), token, token -> callback.onResponse(assignments), errorCallback);
             else
                 callback.onResponse(assignments);
             }, error -> errorCallback.onError(new NetworkError(101303, error.networkResponse.statusCode, "Cannot get assignments!")));
@@ -324,7 +331,7 @@ class KVVModuleList extends HTTPService {
 
 
 
-    public void getEvents(Modules.Module module, final NetworkCallback<Modules.Module> callback, final NetworkErrorCallback errorCallback, boolean forceRefresh) {
+    void getEvents(Modules.Module module, final NetworkCallback<Modules.Module> callback, final NetworkErrorCallback errorCallback, boolean forceRefresh) {
         queueModuleDetails.add(module.getID(), () -> {
             if (module.events != null && !forceRefresh) {
                 callback.onResponse(module);
@@ -374,7 +381,7 @@ class KVVModuleList extends HTTPService {
             events.sort();
             // Empty events *may be* because token is invalid -> check
             if (events.size() == 0)
-                testLogin(token, token -> callback.onResponse(events), errorCallback);
+                testLogin(getContext(), token, token -> callback.onResponse(events), errorCallback);
             else
                 callback.onResponse(events);
         }, error -> errorCallback.onError(new NetworkError(101403, error.networkResponse.statusCode, "Cannot get calendar entries!")));
@@ -384,7 +391,7 @@ class KVVModuleList extends HTTPService {
 
 
 
-    public void getGradebook(Modules.Module module, final NetworkCallback<Modules.Module> callback, final NetworkErrorCallback errorCallback, boolean forceRefresh) {
+    void getGradebook(Modules.Module module, final NetworkCallback<Modules.Module> callback, final NetworkErrorCallback errorCallback, boolean forceRefresh) {
         queueModuleDetails.add(module.getID(), () -> {
             if (module.gradebook != null && !forceRefresh) {
                 callback.onResponse(module);
@@ -471,7 +478,16 @@ class KVVModuleList extends HTTPService {
                     String title = site.getString("title");
                     long modifiedDate = site.getLong("modifiedDate");
                     String url = site.getString("url");
-                    resources.add(new Resource(author, title, modifiedDate, url));
+                    boolean visible = site.getBoolean("visible");
+                    String type = site.getString("type");
+                    String container = site.getString("container");
+                    if (type.equals("collection")){
+                        resources.add(new Resource.Folder(author, title, modifiedDate, url, visible, container));
+                    }
+                    else {
+                        resources.add(new Resource.File(author, title, modifiedDate, url, visible, container, type));
+                    }
+
                 }
 
             } catch (JSONException e) {
@@ -479,38 +495,133 @@ class KVVModuleList extends HTTPService {
                 errorCallback.onError(new NetworkError(101602, 403, "Cannot parse resources!"));
                 return;
             }
+
+            ArrayList<Resource> root = new ArrayList<>();
+            // Generate folder structure
+            for (Resource res: resources) {
+                if (!res.getContainer().equals("/content/group/")) {
+                    if (res.getContainer().equals("/content/group/"+ID+"/")){
+                        // if file in root folder
+                        root.add(res);
+                    } else {
+                        // in sub folder
+                        for (Resource res2: resources) {
+                            if (res2.getUrl().endsWith(res.getContainer()) && res2 instanceof Resource.Folder) {
+                                // Append File/Folder to list
+                                ((Resource.Folder) res2).add(res);
+                            }
+                        }
+                    }
+                }
+            }
+
             // Empty resources *may be* because token is invalid -> check
-            if (resources.size() == 0)
-                testLogin(token, token -> callback.onResponse(resources), errorCallback);
+            if (root.size() == 0)
+                testLogin(getContext(), token, token -> callback.onResponse(root), errorCallback);
             else
-                callback.onResponse(resources);
+                callback.onResponse(root);
 
-
-            callback.onResponse(resources);
         }, error -> errorCallback.onError(new NetworkError(101603, error.networkResponse.statusCode, "Cannot get resources!")));
 
     }
 
-
-
-
-
-
-
-    // TODO Better, more elegant solution than duplicate code KVVLogin
-    private void testLogin(LoginToken loginToken, NetworkCallback<LoginToken> callback, NetworkErrorCallback errorCallback) {
-        get(String.format("https://kvv.imp.fu-berlin.de/direct/profile/%s.json", loginToken.getUsername()), loginToken.getCookies(), response -> {
-            String body = response.getParsed();
-            try {
-                JSONObject json = new JSONObject(body);
-                String displayName = json.getString("displayName");
-                String email = json.getString("email");
-                loginToken.setAdditionals(displayName, email);
-                callback.onResponse(loginToken);
-            } catch (JSONException e) {
-                errorCallback.onError(new NetworkError(100201, 403, "Cannot parse profile!"));
+    void getResourceFile(final NetworkCallback<String> callback, final NetworkErrorCallback errorCallback, String Filename, String url, String moduleName, boolean downloadNew) {
+        if (isExternalStorageReadable()){
+            File f = new File(Environment.getExternalStoragePublicDirectory(
+                    Environment.DIRECTORY_DOWNLOADS)+"/"+moduleName+"/"+Filename);
+            // check if file already downloaded -> do not download again
+            if (f.exists() && !downloadNew) {
+                callback.onResponse(f.getPath());
+                return;
             }
-        }, error -> errorCallback.onError(new NetworkError(100200, error.networkResponse.statusCode, "Testing login failed!")));
+        }
+        getResourceFileUpgrade(Filename, url , moduleName, callback, errorCallback);
+    }
+
+    private void getResourceFileUpgrade(String filename, String url , String moduleName, final NetworkCallback<String> callback, final NetworkErrorCallback errorCallback) {
+        if (token == null) {
+            errorCallback.onError(new NetworkError(101701, 500, "Currently running in offline mode!"));
+            return;
+        }
+
+        get(url, token.getCookies(), response ->{
+
+
+            if (Regex.has("\\.[Uu][Rr][Ll]$", url)){
+                // Return redirected URL
+                String path = response.getHeaders().get("Location");
+                if (path == null){
+                    path = "";
+                }
+                callback.onResponse(path);
+            } else if (response.getBytes()==null){
+                testLogin(getContext(), token, token -> {
+                    if (isExternalStorageWritable()) {
+                        // try to download file again
+                        get(url, token.getCookies(), response2 -> {
+                            String path = saveFileInDownloads(filename, response2, moduleName);
+                            callback.onResponse(path);
+                        }, error -> errorCallback.onError(new NetworkError(101705, error.networkResponse.statusCode, "Cannot get file!")));
+                    } else {
+                        errorCallback.onError(new NetworkError(101703, 403, "External storage not writable!"));
+                    }
+                }, errorCallback);
+            } else if (isExternalStorageWritable()) {
+                String path = saveFileInDownloads(filename, response, moduleName);
+                callback.onResponse(path);
+            } else {
+                errorCallback.onError(new NetworkError(101704, 403, "External storage not writable!"));
+            }
+        }, error -> errorCallback.onError(new NetworkError(101702, error.networkResponse.statusCode, "Cannot get file!")));
+
+
+    }
+
+
+
+
+
+
+
+    /* Checks if external storage is available for read and write */
+    private boolean isExternalStorageWritable() {
+        String state = Environment.getExternalStorageState();
+        if (Environment.MEDIA_MOUNTED.equals(state)) {
+            return true;
+        }
+        log.w("File system: Writing not possible!");
+        return false;
+    }
+
+    /* Checks if external storage is available to at least read */
+    private boolean isExternalStorageReadable() {
+        String state = Environment.getExternalStorageState();
+        if (Environment.MEDIA_MOUNTED.equals(state) ||
+                Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
+            return true;
+        }
+        log.w("File system: Reading not possible!");
+        return false;
+    }
+    private String saveFileInDownloads(String filename, Result fileResult, String moduleName) {
+        // Saves file in folder: DOWNLOADS/moduleName
+        File folder = new File(Environment.getExternalStoragePublicDirectory(
+                Environment.DIRECTORY_DOWNLOADS), moduleName);
+        if (!folder.mkdir()) {
+            log.w( "Directory not created");
+        }
+        String path = "";
+        try {
+            // TODO check if enough storage space is available
+            FileOutputStream out = new FileOutputStream(folder.getPath()+"/"+filename);
+            out.write(fileResult.getBytes());
+            out.close();
+            path = folder.getPath()+"/"+filename;
+        } catch (Exception e) {
+            log.w("File not saved!");
+            e.printStackTrace();
+        }
+        return path;
     }
 
 

app/src/main/java/de/sebse/fuplanner/services/KVV/TestLogin.java

@@ -0,0 +1,38 @@
+package de.sebse.fuplanner.services.KVV;
+
+import android.content.Context;
+
+import org.json.JSONException;
+import org.json.JSONObject;
+
+import de.sebse.fuplanner.services.KVV.types.LoginToken;
+import de.sebse.fuplanner.tools.network.HTTPService;
+import de.sebse.fuplanner.tools.network.NetworkCallback;
+import de.sebse.fuplanner.tools.network.NetworkError;
+import de.sebse.fuplanner.tools.network.NetworkErrorCallback;
+
+final class TestLogin extends HTTPService {
+
+    private TestLogin(Context context) {
+        super(context);
+    }
+
+    static void testLogin(Context context, LoginToken loginToken, NetworkCallback<LoginToken> callback, NetworkErrorCallback errorCallback) {
+        new TestLogin(context).get(String.format("https://kvv.imp.fu-berlin.de/direct/profile/%s.json", loginToken.getUsername()), loginToken.getCookies(), response -> {
+            String body = response.getParsed();
+            if (body == null) {
+                errorCallback.onError(new NetworkError(100202, 403, "Testing login failed!"));
+                return;
+            }
+            try {
+                JSONObject json = new JSONObject(body);
+                String displayName = json.getString("displayName");
+                String email = json.getString("email");
+                loginToken.setAdditionals(displayName, email);
+                callback.onResponse(loginToken);
+            } catch (JSONException e) {
+                errorCallback.onError(new NetworkError(100201, 403, "Cannot parse profile!"));
+            }
+        }, error -> errorCallback.onError(new NetworkError(100200, error.networkResponse.statusCode, "Testing login failed!")));
+    }
+}

app/src/main/java/de/sebse/fuplanner/services/KVV/types/Announcement.java

@@ -25,7 +25,7 @@ public class Announcement implements Serializable {
         return urls;
     }
 
-    public String getId() {
+    private String getId() {
         return id;
     }
 

app/src/main/java/de/sebse/fuplanner/services/KVV/types/Assignment.java

@@ -7,8 +7,6 @@ public class Assignment implements Serializable {
     private final String id;
     private final String title;
     private final long dueTime;
-    private final String gradebookItemName;
-    private final String gradeScale;
     private final ArrayList<String> urls;
     private final String instructions;
 
@@ -16,14 +14,12 @@ public class Assignment implements Serializable {
         this.id = id;
         this.title = title;
         this.dueTime = dueTime;
-        this.gradebookItemName = gradebookItemName;
-        this.gradeScale = gradeScale;
         this.urls = urls;
         //this.grade = grade;
         this.instructions = instructions;
     }
 
-    public String getId() {
+    private String getId() {
         return id;
     }
 
@@ -52,6 +48,6 @@ public class Assignment implements Serializable {
         return "ID: "+getId()+
                 "\nTitle: "+getTitle()+
                 "\nDue date: "+getDueDate()+
-                "\nInstuctions: "+getInstructions().substring(0, Math.min(getInstructions().length(), 100));
+                "\nInstructions: "+getInstructions().substring(0, Math.min(getInstructions().length(), 100));
     }
 }

app/src/main/java/de/sebse/fuplanner/services/KVV/types/Lecturer.java

@@ -5,7 +5,7 @@ import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 public class Lecturer implements Serializable {
-    private final String firstname;
+    private final String firstName;
     private final String surname;
     private final String mail;
 
@@ -15,26 +15,26 @@ public class Lecturer implements Serializable {
         if (!matcher.find()) {
             throw new NoSuchFieldException();
         }
-        this.firstname = matcher.group(1);
+        this.firstName = matcher.group(1);
         this.surname = matcher.group(2);
         this.mail = matcher.group(3);
     }
 
-    public String getFirstname() {
-        return firstname;
+    private String getFirstName() {
+        return firstName;
     }
 
-    public String getSurname() {
+    private String getSurname() {
         return surname;
     }
 
-    public String getMail() {
+    private String getMail() {
         return mail;
     }
 
     @Override
     public String toString() {
-        return "First name: "+getFirstname()+
+        return "First name: "+ getFirstName()+
                 "\nSurname: "+getSurname()+
                 "\nMail: "+getMail();
     }

app/src/main/java/de/sebse/fuplanner/services/KVV/types/LoginToken.java

@@ -1,7 +1,6 @@
 package de.sebse.fuplanner.services.KVV.types;
 
 import android.content.Context;
-import android.support.annotation.Nullable;
 
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
@@ -11,6 +10,8 @@ import java.io.ObjectOutputStream;
 import java.io.Serializable;
 import java.util.HashMap;
 
+import androidx.annotation.Nullable;
+
 /**
  * Created by sebastian on 29.10.17.
  */
@@ -23,7 +24,7 @@ public class LoginToken implements Serializable {
     private final String shibsessionKey;
     private final String shibsessionName;
     private final String JSESSIONID;
-    private String fullname;
+    private String fullName;
     private String email;
     private long saveDate = 0;
 
@@ -58,8 +59,8 @@ public class LoginToken implements Serializable {
         context.deleteFile(FILE_NAME);
     }
 
-    public void setAdditionals(String fullname, String email) {
-        this.fullname = fullname;
+    public void setAdditionals(String fullName, String email) {
+        this.fullName = fullName;
         this.email = email;
     }
 
@@ -79,8 +80,8 @@ public class LoginToken implements Serializable {
         return JSESSIONID;
     }
 
-    public String getFullname() {
-        return fullname;
+    public String getFullName() {
+        return fullName;
     }
 
     public String getEmail() {

app/src/main/java/de/sebse/fuplanner/services/KVV/types/Modules.java

@@ -1,8 +1,6 @@
 package de.sebse.fuplanner.services.KVV.types;
 
 import android.content.Context;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
 
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
@@ -14,6 +12,9 @@ import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.Iterator;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
 /**
  * Created by sebastian on 29.10.17.
  */
@@ -103,9 +104,9 @@ public class Modules implements Iterable<Modules.Module>, Serializable {
 
     public class Module implements Serializable {
         public final String semester;
-        public final HashSet<String> lvNumber;
+        final HashSet<String> lvNumber;
         public final String title;
-        public final HashSet<Lecturer> lecturer;
+        final HashSet<Lecturer> lecturer;
         public final String type;
         public final String description;
         private final String ID;

app/src/main/java/de/sebse/fuplanner/services/KVV/types/Resource.java

@@ -1,22 +1,31 @@
 package de.sebse.fuplanner.services.KVV.types;
 
 import java.io.Serializable;
+import java.util.ArrayList;
+
+import androidx.annotation.LayoutRes;
+import de.sebse.fuplanner.R;
+import de.sebse.fuplanner.tools.ui.treeview.LayoutItemType;
+import de.sebse.fuplanner.tools.ui.treeview.TreeNode;
 
 
+public abstract class Resource implements Serializable {
 
-public class Resource implements Serializable {
-
-    private final String author;
-    private final long modifiedDate;
-    private final String title;
-    private final String url;
+    final String author;
+    final long modifiedDate;
+    final String title;
+    final String url;
+    private final boolean visible;
+    private final String container;
 
 
-    public Resource(String author, String title, long modifiedDate, String url) {
+    Resource(String author, String title, long modifiedDate, String url, boolean visible, String container) {
         this.author = author;
         this.title = title;
         this.modifiedDate = modifiedDate;
         this.url = url;
+        this.visible = visible;
+        this.container = container;
     }
 
     public String getAuthor() {
@@ -35,16 +44,91 @@ public class Resource implements Serializable {
         return url;
     }
 
-    @Override
-    public String toString() {
-        return "Resource{" +
-                "author='" + author + '\'' +
-                ", modifiedDate=" + modifiedDate +
-                ", title='" + title + '\'' +
-                ", url='" + url + '\'' +
-                '}';
+    public String getContainer() {
+        return container;
     }
 
+    public boolean isVisible() {
+        return visible;
+    }
 
+    public abstract TreeNode getTreeNode();
 
+    public static class File extends Resource implements LayoutItemType {
+        private final String type;
+
+        public File(String author, String title, long modifiedDate, String url, boolean visible, String container, String type) {
+            super(author, title, modifiedDate, url, visible, container);
+            this.type = type;
+        }
+
+        @Override
+        public String toString() {
+            return "Resource{" +
+                    "author='" + author + '\'' +
+                    ", modifiedDate=" + modifiedDate +
+                    ", title='" + title + '\'' +
+                    ", url='" + url + '\'' +
+                    ", type='" + type + '\'' +
+                    '}';
+        }
+
+        @Override
+        public TreeNode getTreeNode() {
+            return new TreeNode<>(this);
+        }
+
+        @Override
+        public @LayoutRes int getLayoutId() {
+            return R.layout.item_file;
+        }
+    }
+
+    public static class Folder extends Resource implements LayoutItemType {
+
+        private final ArrayList<Resource> children;
+        public Folder(String author, String title, long modifiedDate, String url, boolean visible, String container) {
+            super(author, title, modifiedDate, url, visible, container);
+            children = new ArrayList<>();
+        }
+
+        public void add(Resource res){
+            children.add(res);
+        }
+
+        public Resource get(int id){
+            return children.get(id);
+        }
+
+        public int size(){
+            return children.size();
+        }
+
+        @Override
+        public String toString() {
+            return "Resource{" +
+                    "author='" + author + '\'' +
+                    ", modifiedDate=" + modifiedDate +
+                    ", title='" + title + '\'' +
+                    ", url='" + url + '\'' +
+                    ", children='" + children + '\'' +
+                    '}';
+        }
+
+        @Override
+        public TreeNode getTreeNode() {
+            TreeNode dir = new TreeNode<>(this);
+            for (Resource res: children) {
+                dir.addChild(res.getTreeNode());
+            }
+            return dir;
+        }
+
+        @Override
+        public @LayoutRes int getLayoutId() {
+            return R.layout.item_dir;
+        }
+    }
 }
+
+

app/src/main/java/de/sebse/fuplanner/services/KVV/types/SortedListModule.java

@@ -43,15 +43,15 @@ public class SortedListModule extends SortedList<Modules.Module, String, String>
         if (b == null)
             return LARGER;
 
-        String s1type = Regex.regex("(S|WS)", a);
-        int s1year = Integer.parseInt(Regex.regex("(S|WS) ([0-9]{2})", a, 2));
-        String s2type = Regex.regex("(S|WS)", b);
-        int s2year = Integer.parseInt(Regex.regex("(S|WS) ([0-9]{2})", b, 2));
+        String s1type = Regex.regex("^(S|WS) ", a);
+        int s1year = Integer.parseInt(Regex.regex("^(S|WS) ([0-9]{2})", a, 2));
+        String s2type = Regex.regex("^(S|WS) ", b);
+        int s2year = Integer.parseInt(Regex.regex("^(S|WS) ([0-9]{2})", b, 2));
 
         if (s1year == s2year) {
             if (s1type.equals(s2type))
                 return EQUAL;
-            return s1type.equals("SS") ? SMALLER : LARGER;
+            return s1type.equals("S") ? SMALLER : LARGER;
         }
         return s1year < s2year ? SMALLER : LARGER;
     }

app/src/main/java/de/sebse/fuplanner/tools/AsyncQueue.java

@@ -8,7 +8,7 @@ import de.sebse.fuplanner.tools.network.NetworkErrorCallback;
 
 public class AsyncQueue {
     private final HashMap<String, LinkedList<AsyncQueueCallback>> mQueues = new HashMap<>();
-    private final HashMap<String, Boolean> mRunnings = new HashMap<>();
+    private final HashMap<String, Boolean> mIsRunning = new HashMap<>();
 
     public void add(String hash, AsyncQueueCallback callback) {
         if (isRunning(hash))
@@ -46,11 +46,11 @@ public class AsyncQueue {
     }
 
     private boolean isRunning(String hash) {
-        return mRunnings.containsKey(hash) && mRunnings.get(hash);
+        return mIsRunning.containsKey(hash) && mIsRunning.get(hash);
     }
 
     private void setRunning(String hash, boolean value) {
-        mRunnings.put(hash, value);
+        mIsRunning.put(hash, value);
     }
 
     private LinkedList<AsyncQueueCallback> getQueue(String hash) {

app/src/main/java/de/sebse/fuplanner/tools/ColorRGB.java

@@ -7,7 +7,7 @@ public class ColorRGB implements Color {
     private final int mGreen;
     private final int mBlue;
 
-    public ColorRGB(int red, int green, int blue) {
+    private ColorRGB(int red, int green, int blue) {
         this.mRed = red;
         this.mGreen = green;
         this.mBlue = blue;

app/src/main/java/de/sebse/fuplanner/tools/ColorRes.java

@@ -1,7 +1,7 @@
 package de.sebse.fuplanner.tools;
 
 import android.graphics.Paint;
-import android.support.annotation.ColorInt;
+import androidx.annotation.ColorInt;
 
 public class ColorRes implements Color {
     @ColorInt private final int mResId;

app/src/main/java/de/sebse/fuplanner/tools/DateSortedList.java

@@ -31,8 +31,8 @@ public abstract class DateSortedList<T> extends ArrayList<T> {
 
     @Override
     public T get(int index) {
-        if (split < 0)
-            sort();
+        //if (split < 0)
+        //    sort();
         if (reversed())
             index = size() - index - 1;
         return super.get(index);

app/src/main/java/de/sebse/fuplanner/tools/MainAcitivityListener.java

@@ -1,23 +0,0 @@
-package de.sebse.fuplanner.tools;
-
-import android.support.annotation.StringRes;
-
-import de.sebse.fuplanner.services.Canteen.CanteenBrowser;
-import de.sebse.fuplanner.services.GoogleAuth.GoogleAuth;
-import de.sebse.fuplanner.services.KVV.KVV;
-
-public interface MainAcitivityListener {
-    void onTitleTextChange(String newTitle);
-
-    void onTitleTextChange(@StringRes int titleId);
-
-    KVV getKVV();
-
-    GoogleAuth getGoogleAuth();
-
-    void loginTokenInvalid(boolean doPrecheck);
-
-    void refreshFailed(boolean isFailed);
-
-    CanteenBrowser getCanteenBrowser();
-}

app/src/main/java/de/sebse/fuplanner/tools/MainActivityListener.java

@@ -0,0 +1,31 @@
+package de.sebse.fuplanner.tools;
+
+import androidx.annotation.StringRes;
+
+import de.sebse.fuplanner.services.Canteen.CanteenBrowser;
+import de.sebse.fuplanner.services.GoogleAuth.GoogleAuth;
+import de.sebse.fuplanner.services.KVV.KVV;
+
+public interface MainActivityListener {
+    void onTitleTextChange(String newTitle);
+
+    void onTitleTextChange(@StringRes int titleId);
+
+    KVV getKVV();
+
+    GoogleAuth getGoogleAuth();
+
+    void loginTokenInvalid(boolean doLoginCheck);
+
+    void onRefreshCompleted(boolean isFailed);
+
+    CanteenBrowser getCanteenBrowser();
+
+    void addRequestPermissionsResultListener(RequestPermissionsResultListener listener, String id);
+
+    void removeRequestPermissionsResultListener(String id);
+
+    void showToast(@StringRes int msgStringRes);
+
+    void showToast(String message);
+}

app/src/main/java/de/sebse/fuplanner/tools/Preferences.java

@@ -1,8 +1,8 @@
 package de.sebse.fuplanner.tools;
 
 import android.content.Context;
-import android.support.annotation.ArrayRes;
-import android.support.v7.preference.PreferenceManager;
+import androidx.annotation.ArrayRes;
+import androidx.preference.PreferenceManager;
 
 public class Preferences {
     public static String getString(Context context, @ArrayRes int key) {

app/src/main/java/de/sebse/fuplanner/tools/Regex.java

@@ -9,6 +9,14 @@ import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 public class Regex {
+    public static boolean has(@Language("Regexp") String regex, String match) {
+        try {
+            regex(regex, match, 0);
+            return true;
+        } catch (NoSuchFieldException e) {
+            return false;
+        }
+    }
     public static String regex(@Language("Regexp") String regex, String match) throws NoSuchFieldException {
         return regex(regex, match, 1);
     }

app/src/main/java/de/sebse/fuplanner/tools/RequestPermissionsResultListener.java

@@ -0,0 +1,5 @@
+package de.sebse.fuplanner.tools;
+
+public interface RequestPermissionsResultListener {
+    void callback(int requestCode, String[] permissions, int[] grantResults);
+}

app/src/main/java/de/sebse/fuplanner/tools/SortedList.java

@@ -1,7 +1,7 @@
 package de.sebse.fuplanner.tools;
 
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 
 import java.io.Serializable;
 import java.util.ArrayList;
@@ -25,6 +25,7 @@ public abstract class SortedList<T, I, F> implements Iterable<T>, Serializable {
 
     protected abstract boolean hasIdentifier(T o1, I id);
 
+    @SuppressWarnings("BooleanMethodIsAlwaysInverted")
     protected abstract boolean hasFilter(T o1, F filter);
 
     @Nullable

app/src/main/java/de/sebse/fuplanner/tools/UtilsDate.java

@@ -4,16 +4,14 @@ import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
 import android.content.Context;
 import android.os.Build;
-import android.support.annotation.Nullable;
+import androidx.annotation.Nullable;
 import android.text.format.DateFormat;
 
-import com.google.android.gms.common.logging.Logger;
-
 import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.Locale;
 
-public class DateUtils {
+public class UtilsDate {
     @Deprecated
     public static String getModifiedDateTime(long modified) {
         return getModifiedDateTime(null, modified);

app/src/main/java/de/sebse/fuplanner/tools/UtilsUi.java

@@ -0,0 +1,17 @@
+package de.sebse.fuplanner.tools;
+
+import android.content.Context;
+import android.content.res.Resources;
+import android.util.DisplayMetrics;
+
+public class UtilsUi {
+    public static float convertPixelsToDp(float px, Context context) {
+        Resources resources = context.getResources();
+        DisplayMetrics metrics = resources.getDisplayMetrics();
+        return px / ((float) metrics.densityDpi / DisplayMetrics.DENSITY_DEFAULT);
+    }
+
+    public static float convertDpToPixels(Context context, float dp) {
+        return dp * context.getResources().getDisplayMetrics().density;
+    }
+}

app/src/main/java/de/sebse/fuplanner/tools/logging/Logger.java

@@ -10,10 +10,14 @@ public class Logger {
     }
 
     public Logger(Object object) {
+        this.tag = getClassName(object);
+    }
+
+    private static String getClassName(Object object) {
         if (object instanceof String)
-            this.tag = (String) object;
+            return (String) object;
         else
-            this.tag = object.getClass().getSimpleName();
+            return object.getClass().getSimpleName();
     }
 
     public void d(Object... msg) {

app/src/main/java/de/sebse/fuplanner/tools/network/BetterHurlStack.java

@@ -1,24 +1,18 @@
 package de.sebse.fuplanner.tools.network;
 
 import com.android.volley.AuthFailureError;
+import com.android.volley.Header;
 import com.android.volley.Request;
+import com.android.volley.toolbox.HttpResponse;
 import com.android.volley.toolbox.HurlStack;
 
-import org.apache.http.Header;
-import org.apache.http.HttpEntity;
-import org.apache.http.HttpResponse;
-import org.apache.http.ProtocolVersion;
-import org.apache.http.StatusLine;
-import org.apache.http.entity.BasicHttpEntity;
-import org.apache.http.message.BasicHeader;
-import org.apache.http.message.BasicHttpResponse;
-import org.apache.http.message.BasicStatusLine;
-
 import java.io.DataOutputStream;
+import java.io.FilterInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.net.HttpURLConnection;
 import java.net.URL;
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -28,12 +22,15 @@ import java.util.regex.Pattern;
 import javax.net.ssl.HttpsURLConnection;
 import javax.net.ssl.SSLSocketFactory;
 
+import androidx.annotation.VisibleForTesting;
+
 /**
  * Created by sebastian on 29.10.17.
  */
 
 public class BetterHurlStack extends HurlStack {
     private static final String HEADER_CONTENT_TYPE = "Content-Type";
+    private static final int HTTP_CONTINUE = 100;
 
     private final UrlRewriter mUrlRewriter;
     private final SSLSocketFactory mSslSocketFactory;
@@ -50,14 +47,14 @@ public class BetterHurlStack extends HurlStack {
     /**
      * @param urlRewriter Rewriter to use for request URLs
      */
-    BetterHurlStack(boolean followRedirects, UrlRewriter urlRewriter) {
+    private BetterHurlStack(boolean followRedirects, UrlRewriter urlRewriter) {
         this(followRedirects, urlRewriter, null);
     }
     /**
      * @param urlRewriter Rewriter to use for request URLs
      * @param sslSocketFactory SSL factory to use for HTTPS connections
      */
-    BetterHurlStack(boolean followRedirects, UrlRewriter urlRewriter, SSLSocketFactory sslSocketFactory) {
+    private BetterHurlStack(boolean followRedirects, UrlRewriter urlRewriter, SSLSocketFactory sslSocketFactory) {
         super(urlRewriter, sslSocketFactory);
         mUrlRewriter = urlRewriter;
         mSslSocketFactory = sslSocketFactory;
@@ -76,12 +73,12 @@ public class BetterHurlStack extends HurlStack {
     }
 
     @Override
-    public HttpResponse performRequest(Request<?> request, Map<String, String> additionalHeaders)
+    public HttpResponse executeRequest(Request<?> request, Map<String, String> additionalHeaders)
             throws IOException, AuthFailureError {
         String url = request.getUrl();
         HashMap<String, String> map = new HashMap<>();
-        map.putAll(request.getHeaders());
         map.putAll(additionalHeaders);
+        map.putAll(request.getHeaders());
         if (mUrlRewriter != null) {
             String rewritten = mUrlRewriter.rewriteUrl(url);
             if (rewritten == null) {
@@ -91,67 +88,85 @@ public class BetterHurlStack extends HurlStack {
         }
         URL parsedUrl = new URL(url);
         HttpURLConnection connection = openConnection(parsedUrl, request);
-        for (String headerName : map.keySet()) {
-            connection.addRequestProperty(headerName, map.get(headerName));
+        boolean keepConnectionOpen = false;
+        try {
+            for (String headerName : map.keySet()) {
+                connection.setRequestProperty(headerName, map.get(headerName));
+            }
+            setConnectionParametersForRequest(connection, request);
+            // Initialize HttpResponse with data from the HttpURLConnection.
+            int responseCode = connection.getResponseCode();
+            if (responseCode == -1) {
+                // -1 is returned by getResponseCode() if the response code could not be retrieved.
+                // Signal to the caller that something was wrong with the connection.
+                throw new IOException("Could not retrieve response code from HttpUrlConnection.");
+            }
+
+            if (!hasResponseBody(request.getMethod(), responseCode)) {
+                return new HttpResponse(responseCode, convertHeaders(connection.getHeaderFields()));
+            }
+
+            // Need to keep the connection open until the stream is consumed by the caller. Wrap the
+            // stream such that close() will disconnect the connection.
+            keepConnectionOpen = true;
+            return new HttpResponse(
+                    responseCode,
+                    convertHeaders(connection.getHeaderFields()),
+                    connection.getContentLength(),
+                    new UrlConnectionInputStream(connection));
+
+        } finally {
+            if (!keepConnectionOpen) {
+                connection.disconnect();
+            }
         }
-        setConnectionParametersForRequest(connection, request);
-        // Initialize HttpResponse with data from the HttpURLConnection.
-        ProtocolVersion protocolVersion = new ProtocolVersion("HTTP", 1, 1);
-        int responseCode = connection.getResponseCode();
-        if (responseCode == -1) {
-            // -1 is returned by getResponseCode() if the response code could not be retrieved.
-            // Signal to the caller that something was wrong with the connection.
-            throw new IOException("Could not retrieve response code from HttpUrlConnection.");
-        }
-        StatusLine responseStatus = new BasicStatusLine(protocolVersion,
-                connection.getResponseCode(), connection.getResponseMessage());
-        BasicHttpResponse response = new BasicHttpResponse(responseStatus);
-        response.setEntity(entityFromConnection(connection));
-        for (Map.Entry<String, List<String>> header : connection.getHeaderFields().entrySet()) {
-            if (header.getKey() != null) {
-                Header h;
-                if (header.getKey().equals("Set-Cookie")) {
+    }
+
+    @VisibleForTesting
+    private static List<Header> convertHeaders(Map<String, List<String>> responseHeaders) {
+        List<Header> headerList = new ArrayList<>(responseHeaders.size());
+        for (Map.Entry<String, List<String>> entry : responseHeaders.entrySet()) {
+            // HttpUrlConnection includes the status line as a header with a null key; omit it here
+            // since it's not really a header and the rest of Volley assumes non-null keys.
+            if (entry.getKey() != null) {
+                if (entry.getKey().equals("Set-Cookie")) {
                     Pattern pattern = Pattern.compile("^([^=]+=[^;]+;)");
                     StringBuilder cookieValue = new StringBuilder();
-                    for (String value: header.getValue()) {
+                    for (String value : entry.getValue()) {
                         Matcher matcher = pattern.matcher(value);
                         if (matcher.find()) {
                             cookieValue.append(matcher.group(1));
                         }
                     }
-                    h = new BasicHeader(header.getKey(), cookieValue.toString());
+                    headerList.add(new Header(entry.getKey(), cookieValue.toString()));
                 } else {
-                    h = new BasicHeader(header.getKey(), header.getValue().get(0));
+                    headerList.add(new Header(entry.getKey(), entry.getValue().get(0)));
                 }
-                response.addHeader(h);
             }
         }
-        return response;
+        return headerList;
     }
 
     /**
-     * Initializes an {@link HttpEntity} from the given {@link HttpURLConnection}.
-     * @param connection A http connection
-     * @return an HttpEntity populated with data from <code>connection</code>.
+     * Checks if a response message contains a body.
+     *
+     * @see <a href="https://tools.ietf.org/html/rfc7230#section-3.3">RFC 7230 section 3.3</a>
+     * @param requestMethod request method
+     * @param responseCode response status code
+     * @return whether the response has a body
      */
-    private static HttpEntity entityFromConnection(HttpURLConnection connection) {
-        BasicHttpEntity entity = new BasicHttpEntity();
-        InputStream inputStream;
-        try {
-            inputStream = connection.getInputStream();
-        } catch (IOException ioe) {
-            inputStream = connection.getErrorStream();
-        }
-        entity.setContent(inputStream);
-        entity.setContentLength(connection.getContentLength());
-        entity.setContentEncoding(connection.getContentEncoding());
-        entity.setContentType(connection.getContentType());
-        return entity;
+    private static boolean hasResponseBody(int requestMethod, int responseCode) {
+        return requestMethod != Request.Method.HEAD
+                && !(HTTP_CONTINUE <= responseCode && responseCode < HttpURLConnection.HTTP_OK)
+                && responseCode != HttpURLConnection.HTTP_NO_CONTENT
+                && responseCode != HttpURLConnection.HTTP_NOT_MODIFIED;
     }
 
+    // NOTE: Any request headers added here (via setRequestProperty or addRequestProperty) should be
+    // checked against the existing properties in the connection and not overridden if already set.
     @SuppressWarnings("deprecation")
-    /* package */ static void setConnectionParametersForRequest(HttpURLConnection connection,
-                                                                Request<?> request) throws IOException, AuthFailureError {
+    /* package */ private static void setConnectionParametersForRequest(
+            HttpURLConnection connection, Request<?> request) throws IOException, AuthFailureError {
         switch (request.getMethod()) {
             case Request.Method.DEPRECATED_GET_OR_POST:
                 // This is the deprecated way that needs to be handled for backwards compatibility.
@@ -159,16 +174,8 @@ public class BetterHurlStack extends HurlStack {
                 // GET.  Otherwise, it is assumed that the request is a POST.
                 byte[] postBody = request.getPostBody();
                 if (postBody != null) {
-                    // Prepare output. There is no need to set Content-Length explicitly,
-                    // since this is handled by HttpURLConnection using the size of the prepared
-                    // output stream.
-                    connection.setDoOutput(true);
                     connection.setRequestMethod("POST");
-                    connection.addRequestProperty(HEADER_CONTENT_TYPE,
-                            request.getPostBodyContentType());
-                    DataOutputStream out = new DataOutputStream(connection.getOutputStream());
-                    out.write(postBody);
-                    out.close();
+                    addBody(connection, request, postBody);
                 }
                 break;
             case Request.Method.GET:
@@ -209,14 +216,26 @@ public class BetterHurlStack extends HurlStack {
             throws IOException, AuthFailureError {
         byte[] body = request.getBody();
         if (body != null) {
-            connection.setDoOutput(true);
-            connection.addRequestProperty(HEADER_CONTENT_TYPE, request.getBodyContentType());
-            DataOutputStream out = new DataOutputStream(connection.getOutputStream());
-            out.write(body);
-            out.close();
+            addBody(connection, request, body);
         }
     }
 
+    private static void addBody(HttpURLConnection connection, Request<?> request, byte[] body)
+            throws IOException {
+        // Prepare output. There is no need to set Content-Length explicitly,
+        // since this is handled by HttpURLConnection using the size of the prepared
+        // output stream.
+        connection.setDoOutput(true);
+        // Set the content-type unless it was already set (by Request#getHeaders).
+        if (!connection.getRequestProperties().containsKey(HEADER_CONTENT_TYPE)) {
+            connection.setRequestProperty(
+                    HEADER_CONTENT_TYPE, request.getBodyContentType());
+        }
+        DataOutputStream out = new DataOutputStream(connection.getOutputStream());
+        out.write(body);
+        out.close();
+    }
+
     private HttpURLConnection openConnection(URL url, Request<?> request) throws IOException {
         HttpURLConnection connection = createConnection(url);
         int timeoutMs = request.getTimeoutMs();
@@ -230,4 +249,40 @@ public class BetterHurlStack extends HurlStack {
         }
         return connection;
     }
+
+
+    /**
+     * Wrapper for a {@link HttpURLConnection}'s InputStream which disconnects the connection on
+     * stream close.
+     */
+    static class UrlConnectionInputStream extends FilterInputStream {
+        private final HttpURLConnection mConnection;
+
+        UrlConnectionInputStream(HttpURLConnection connection) {
+            super(inputStreamFromConnection(connection));
+            mConnection = connection;
+        }
+
+        @Override
+        public void close() throws IOException {
+            super.close();
+            mConnection.disconnect();
+        }
+    }
+
+    /**
+     * Initializes an {@link InputStream} from the given {@link HttpURLConnection}.
+     *
+     * @param connection A http url connection
+     * @return an HttpEntity populated with data from <code>connection</code>.
+     */
+    private static InputStream inputStreamFromConnection(HttpURLConnection connection) {
+        InputStream inputStream;
+        try {
+            inputStream = connection.getInputStream();
+        } catch (IOException ioe) {
+            inputStream = connection.getErrorStream();
+        }
+        return inputStream;
+    }
 }

app/src/main/java/de/sebse/fuplanner/tools/network/HTTPService.java

@@ -1,7 +1,6 @@
 package de.sebse.fuplanner.tools.network;
 
 import android.content.Context;
-import android.support.annotation.Nullable;
 
 import com.android.volley.AuthFailureError;
 import com.android.volley.NetworkResponse;
@@ -17,6 +16,7 @@ import java.net.URLEncoder;
 import java.util.HashMap;
 import java.util.Map;
 
+import androidx.annotation.Nullable;
 import de.sebse.fuplanner.tools.logging.Logger;
 
 /**
@@ -25,14 +25,12 @@ import de.sebse.fuplanner.tools.logging.Logger;
 
 public class HTTPService {
     private final RequestQueue requestQueue;
+    private final Context mContext;
     protected Logger log = new Logger(this);
 
     protected HTTPService(Context context) {
-        this(context, false);
-    }
-
-    protected HTTPService(Context context, boolean followRedirects) {
-        requestQueue = Volley.newRequestQueue(context, new BetterHurlStack(followRedirects));
+        this.mContext = context;
+        requestQueue = Volley.newRequestQueue(context, new BetterHurlStack(false));
     }
 
     protected void get(String url, @Nullable final HashMap<String, String> cookies, Response.Listener<Result> response, Response.ErrorListener error) {
@@ -40,14 +38,14 @@ public class HTTPService {
             @Override
             public void deliverError(VolleyError error) {
                 if (error == null) {
-                    super.deliverError(new VolleyError(new NetworkResponse(500, null, null, true, 0)));
+                    super.deliverError(new VolleyError(new NetworkResponse(500, null, true, 0, null)));
                 } else if (error.networkResponse == null) {
                     int statusCode;
                     if (error instanceof TimeoutError)
                         statusCode = 408;
                     else
                         statusCode = 500;
-                    super.deliverError(new VolleyError(new NetworkResponse(statusCode, null, null, true, error.getNetworkTimeMs())));
+                    super.deliverError(new VolleyError(new NetworkResponse(statusCode, null, true, error.getNetworkTimeMs(), null)));
                 } else {
                     final int status = error.networkResponse.statusCode;
                     if (status == 302) {
@@ -96,7 +94,6 @@ public class HTTPService {
                         sb.append('&');
                     }
                     try {
-                        //Log.e("Superissimo", e.getKey()+"|||"+e.getValue());
                         sb.append(URLEncoder.encode(e.getKey(), "UTF-8")).append('=').append(URLEncoder.encode(e.getValue(), "UTF-8"));
                     } catch (UnsupportedEncodingException ignored) {
                     }
@@ -112,14 +109,14 @@ public class HTTPService {
             @Override
             public void deliverError(VolleyError error) {
                 if (error == null) {
-                    super.deliverError(new VolleyError(new NetworkResponse(500, null, null, true, 0)));
+                    super.deliverError(new VolleyError(new NetworkResponse(500, null, true, 0, null)));
                 } else if (error.networkResponse == null) {
                     int statusCode;
                     if (error instanceof TimeoutError)
                         statusCode = 408;
                     else
                         statusCode = 500;
-                    super.deliverError(new VolleyError(new NetworkResponse(statusCode, null, null, true, error.getNetworkTimeMs())));
+                    super.deliverError(new VolleyError(new NetworkResponse(statusCode, null, true, error.getNetworkTimeMs(), null)));
                 } else {
                     final int status = error.networkResponse.statusCode;
                     if (status == 302) {
@@ -149,4 +146,8 @@ public class HTTPService {
         };
         requestQueue.add(request);
     }
+
+    protected Context getContext() {
+        return mContext;
+    }
 }

app/src/main/java/de/sebse/fuplanner/tools/network/HttpRequest.java

@@ -6,8 +6,6 @@ import com.android.volley.Request;
 import com.android.volley.Response;
 import com.android.volley.toolbox.HttpHeaderParser;
 
-import java.io.UnsupportedEncodingException;
-
 /**
  * Created by sebastian on 24.10.17.
  */
@@ -28,13 +26,7 @@ class HttpRequest extends Request<Result> {
 
     @Override
     protected Response<Result> parseNetworkResponse(NetworkResponse response) {
-        String parsed;
-        try {
-            parsed = new String(response.data, HttpHeaderParser.parseCharset(response.headers));
-        } catch (UnsupportedEncodingException e) {
-            parsed = new String(response.data);
-        }
-        Result result = new Result(parsed, response.headers);
+        Result result = new Result(response.data, response.headers);
 
         return Response.success(result, HttpHeaderParser.parseCacheHeaders(response));
     }

app/src/main/java/de/sebse/fuplanner/tools/network/NetworkCallback.java

@@ -1,6 +1,6 @@
 package de.sebse.fuplanner.tools.network;
 
-import android.support.annotation.NonNull;
+import androidx.annotation.NonNull;
 
 public interface NetworkCallback<T> {
     void onResponse(@NonNull T success);

app/src/main/java/de/sebse/fuplanner/tools/network/NetworkError.java

@@ -23,7 +23,7 @@ public class NetworkError {
         return httpStatus;
     }
 
-    public String getMessage() {
+    private String getMessage() {
         return message;
     }
 

app/src/main/java/de/sebse/fuplanner/tools/network/Result.java

@@ -1,21 +1,38 @@
 package de.sebse.fuplanner.tools.network;
 
+import com.android.volley.toolbox.HttpHeaderParser;
+
+import java.io.UnsupportedEncodingException;
 import java.util.Map;
 
+import androidx.annotation.Nullable;
+
 /**
  * Created by sebastian on 24.10.17.
  */
 public class Result {
-    private final String parsed;
+    @Nullable private final byte[] body;
     private final Map<String, String> headers;
 
-    public Result(String parsed, Map<String, String> headers) {
-        this.parsed = parsed;
+    Result(@Nullable byte[] body, Map<String, String> headers) {
+        this.body = body;
         this.headers = headers;
     }
 
+    @Nullable
     public String getParsed() {
-        return parsed;
+        if (this.body == null)
+            return null;
+        try {
+            return new String(this.body, HttpHeaderParser.parseCharset(headers));
+        } catch (UnsupportedEncodingException e) {
+            return new String(this.body);
+        }
+    }
+
+    @Nullable
+    public byte[] getBytes() {
+        return body;
     }
 
     public Map<String, String> getHeaders() {

app/src/main/java/de/sebse/fuplanner/tools/ui/CustomViewHolder.java

@@ -1,8 +1,9 @@
 package de.sebse.fuplanner.tools.ui;
 
-import android.support.v7.widget.RecyclerView;
 import android.view.View;
 
+import androidx.recyclerview.widget.RecyclerView;
+
 public class CustomViewHolder extends RecyclerView.ViewHolder {
     public final View mView;
 

app/src/main/java/de/sebse/fuplanner/tools/ui/ExpandableCardViewHolder.java

@@ -0,0 +1,27 @@
+package de.sebse.fuplanner.tools.ui;
+
+import android.view.View;
+
+import de.sebse.fuplanner.tools.ui.cardview.ExpandableCardView;
+
+public class ExpandableCardViewHolder extends CustomViewHolder {
+    ExpandableCardViewHolder(View view) {
+        super(view);
+    }
+
+    public void reset() {
+        getView().reset();
+    }
+
+    private ExpandableCardView getView() {
+        return (ExpandableCardView) mView;
+    }
+
+    View getOuterView() {
+        return getView().getOuterView();
+    }
+
+    View getInnerView() {
+        return getView().getInnerView();
+    }
+}

app/src/main/java/de/sebse/fuplanner/tools/ui/ItemViewHolder.java

@@ -9,7 +9,7 @@ public class ItemViewHolder extends CustomViewHolder {
     public final TextView mTitle;
     public final TextView mSubLeft;
     public final TextView mSubRight;
-    public final TextView mTopRight;
+    private final TextView mTopRight;
 
     public ItemViewHolder(View view) {
         super(view);

app/src/main/java/de/sebse/fuplanner/tools/ui/MealViewHolder.java

@@ -0,0 +1,39 @@
+package de.sebse.fuplanner.tools.ui;
+
+import android.view.View;
+import android.widget.ImageView;
+import android.widget.TextView;
+
+import de.sebse.fuplanner.R;
+
+public class MealViewHolder extends ExpandableCardViewHolder {
+    public final TextView mTitle;
+    public final TextView mSubTitle;
+    public final TextView mCategory;
+    public final TextView mNotes;
+
+    public final ImageView mIconVegan;
+    public final ImageView mIconVegetarian;
+    public final ImageView mIconBio;
+    public final ImageView mIconMsc;
+
+
+    public MealViewHolder(View view) {
+        super(view);
+        View outerView = getOuterView();
+        View innerView = getInnerView();
+        mTitle = outerView.findViewById(R.id.title);
+        mSubTitle = outerView.findViewById(R.id.sub_title);
+        mNotes = innerView.findViewById(R.id.notes);
+        mCategory = innerView.findViewById(R.id.category);
+        mIconVegan = innerView.findViewById(R.id.icon_vegan);
+        mIconVegetarian = innerView.findViewById(R.id.icon_vegetarian);
+        mIconBio = innerView.findViewById(R.id.icon_organic);
+        mIconMsc = innerView.findViewById(R.id.icon_msc);
+    }
+
+    @Override
+    public String toString() {
+        return super.toString() + " '" + mTitle.getText() + "' '" + mSubTitle.getText() + "'";
+    }
+}

app/src/main/java/de/sebse/fuplanner/tools/ui/cardview/ExpandableCardView.java

@@ -0,0 +1,368 @@
+package de.sebse.fuplanner.tools.ui.cardview;
+
+
+import android.content.Context;
+import android.content.res.TypedArray;
+import android.os.Build;
+import android.util.AttributeSet;
+import android.util.TypedValue;
+import android.view.View;
+import android.view.animation.Animation;
+import android.view.animation.RotateAnimation;
+import android.view.animation.Transformation;
+import android.widget.ImageButton;
+
+import androidx.annotation.LayoutRes;
+import androidx.annotation.Nullable;
+import androidx.cardview.widget.CardView;
+import de.sebse.fuplanner.R;
+import de.sebse.fuplanner.tools.UtilsUi;
+import de.sebse.fuplanner.tools.logging.Logger;
+
+/**
+ *
+ * Copyright (c) 2018 Alessandro Sperotti
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ *
+ * Created by alessandros on 23/02/2018.
+ * @author Alessandro Sperotti
+ */
+
+public class ExpandableCardView extends CardView {
+    private int innerViewRes;
+    private int outerViewRes;
+
+    private View innerView;
+    private View outerView;
+    private ImageButton imageButton;
+
+    private static final int DEFAULT_ANIM_DURATION = 350;
+    private long animDuration = DEFAULT_ANIM_DURATION;
+
+    private final static int COLLAPSING = 0;
+    private final static int EXPANDING = 1;
+
+    private boolean isExpanded = false;
+    private boolean isExpanding = false;
+    private boolean isCollapsing = false;
+    private boolean startExpanded = false;
+
+    private int collapsedHeight = 0;
+    private int expandedHeight = 0;
+
+    private OnExpandedListener listener;
+
+    private OnClickListener defaultClickListener = v -> {
+        if(isExpanded()) collapse();
+        else expand();
+    };
+    private Logger log = new Logger(this);
+
+    public ExpandableCardView(Context context) {
+        super(context);
+        initView(context);
+    }
+
+    public ExpandableCardView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+
+        initAttributes(context, attrs);
+        initView(context);
+    }
+
+    public ExpandableCardView(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+
+        initAttributes(context, attrs);
+        initView(context);
+    }
+
+    private void initView(Context context){
+        //Inflating View
+        imageButton = new ImageButton(context);
+        imageButton.setImageDrawable(getResources().getDrawable(R.drawable.arrow_down));
+        imageButton.setPadding(
+                (int) UtilsUi.convertDpToPixels(getContext(), 10),
+                (int) UtilsUi.convertDpToPixels(getContext(), 10),
+                (int) UtilsUi.convertDpToPixels(getContext(), 10),
+                (int) UtilsUi.convertDpToPixels(getContext(), 10)
+        );
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
+            TypedValue outValue = new TypedValue();
+            context.getTheme().resolveAttribute(android.R.attr.selectableItemBackground, outValue, true);
+            imageButton.setBackgroundResource(outValue.resourceId);
+        }
+        isExpanded = startExpanded;
+    }
+
+    private void initAttributes(Context context, AttributeSet attrs){
+        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.ExpandableCardView);
+
+        innerViewRes = typedArray.getResourceId(R.styleable.ExpandableCardView_inner_view, View.NO_ID);
+        outerViewRes = typedArray.getResourceId(R.styleable.ExpandableCardView_outer_view, View.NO_ID);
+        animDuration = typedArray.getInteger(R.styleable.ExpandableCardView_animationDuration, DEFAULT_ANIM_DURATION);
+        startExpanded = typedArray.getBoolean(R.styleable.ExpandableCardView_startExpanded, false);
+        typedArray.recycle();
+    }
+
+    @Override
+    protected void onFinishInflate() {
+        super.onFinishInflate();
+
+        innerView = inflateChild(innerViewRes);
+        outerView = inflateChild(outerViewRes);
+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+            setElevation(UtilsUi.convertDpToPixels(getContext(), 4));
+        }
+
+        setOnClickListener(defaultClickListener);
+    }
+
+    @Override
+    protected void onLayout(boolean changed, int l, int t, int r, int b) {
+        removeAllViews();
+        int x = getPaddingLeft();
+        int y = getPaddingTop();
+        addView(outerView);
+        outerView.layout(x, y, x+outerView.getMeasuredWidth(), y+outerView.getMeasuredHeight());
+        addView(imageButton);
+        imageButton.layout(
+                getMeasuredWidth() - getPaddingRight() - imageButton.getMeasuredWidth(),
+                y,
+                getMeasuredWidth() - getPaddingRight(),
+                y+imageButton.getMeasuredHeight()
+        );
+        addView(innerView);
+        innerView.layout(x, y+outerView.getMeasuredHeight(), x+innerView.getMeasuredWidth(), y+outerView.getMeasuredHeight()+innerView.getMeasuredHeight());
+    }
+
+    @Override
+    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+        if (MeasureSpec.getSize(widthMeasureSpec) == 0 && MeasureSpec.getMode(widthMeasureSpec) != MeasureSpec.UNSPECIFIED || MeasureSpec.getSize(heightMeasureSpec) == 0 && MeasureSpec.getMode(heightMeasureSpec) != MeasureSpec.UNSPECIFIED) {
+            log.w("This should not happen! Invalid dimension size");
+            setMeasuredDimension(reconcileSize(10, widthMeasureSpec), reconcileSize(10, heightMeasureSpec));
+            return;
+        }
+
+        int desiredWidth;
+        int desiredHeight;
+
+        int widthMeasure = atMostSpec(MeasureSpec.getSize(widthMeasureSpec), widthMeasureSpec);
+        int heightMeasure = atMostSpec(MeasureSpec.getSize(heightMeasureSpec), heightMeasureSpec);
+        imageButton.measure(widthMeasure, heightMeasure);
+
+        widthMeasure = atMostExactlySpec(Math.max(0, MeasureSpec.getSize(widthMeasureSpec)-imageButton.getMeasuredWidth()), widthMeasureSpec);
+        heightMeasure = atMostSpec(MeasureSpec.getSize(heightMeasureSpec), heightMeasureSpec);
+        outerView.measure(widthMeasure, heightMeasure);
+        desiredWidth = imageButton.getMeasuredWidth() + outerView.getMeasuredWidth();
+        desiredHeight = Math.max(imageButton.getMeasuredHeight(), outerView.getMeasuredHeight());
+
+        widthMeasure = atMostSpec(MeasureSpec.getSize(widthMeasureSpec), widthMeasureSpec);
+        heightMeasure = atMostSpec(Math.max(0, MeasureSpec.getSize(heightMeasureSpec)-desiredHeight), heightMeasureSpec);
+        innerView.measure(widthMeasure, heightMeasure);
+        desiredWidth = Math.max(desiredWidth, innerView.getMeasuredWidth());
+        desiredHeight += innerView.getMeasuredHeight();
+
+        desiredWidth += getPaddingLeft() + getPaddingRight();
+        desiredHeight += getPaddingTop() + getPaddingBottom();
+
+        if (MeasureSpec.getMode(heightMeasureSpec) != MeasureSpec.EXACTLY) {
+            expandedHeight = desiredHeight;
+            collapsedHeight = desiredHeight - innerView.getMeasuredHeight();
+        }
+
+        setMeasuredDimension(reconcileSize(desiredWidth, widthMeasureSpec), reconcileSize(isExpanded ? expandedHeight : collapsedHeight, heightMeasureSpec));
+    }
+
+    private void expand() {
+        final int initialHeight = this.getHeight();
+        int targetHeight = expandedHeight;
+
+        if(targetHeight - initialHeight != 0) {
+            animateViews(initialHeight, targetHeight - initialHeight, EXPANDING);
+        }
+    }
+
+    private void collapse() {
+        final int initialHeight = this.getHeight();
+        int targetHeight = collapsedHeight;
+
+        if(initialHeight - targetHeight != 0) {
+            animateViews(initialHeight, initialHeight - targetHeight, COLLAPSING);
+        }
+
+    }
+
+    private boolean isExpanded() {
+        return isExpanded;
+    }
+
+    private void animateViews(final int initialHeight, final int distance, final int animationType){
+
+        Animation expandAnimation = new Animation() {
+            @Override
+            protected void applyTransformation(float interpolatedTime, Transformation t) {
+                if (interpolatedTime == 1) {
+                    //Setting isExpanding/isCollapsing to false
+                    isExpanding = false;
+                    isCollapsing = false;
+
+                    if (listener != null) {
+                        if (animationType == EXPANDING)
+                            listener.onExpandChanged(ExpandableCardView.this, true);
+                        else
+                            listener.onExpandChanged(ExpandableCardView.this, false);
+                    }
+                }
+
+                ExpandableCardView.this.getLayoutParams().height = animationType == EXPANDING
+                        ? (int) (initialHeight + (distance * interpolatedTime))
+                        : (int) (initialHeight - (distance * interpolatedTime));
+                ExpandableCardView.this.requestLayout();
+
+            }
+
+            @Override
+            public boolean willChangeBounds() {
+                return true;
+            }
+        };
+
+        RotateAnimation arrowAnimation = animationType == EXPANDING ?
+                new RotateAnimation(0,180,Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF,
+                        0.5f) :
+                new RotateAnimation(180,0,Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF,
+                        0.5f);
+
+        arrowAnimation.setFillAfter(true);
+
+
+        arrowAnimation.setDuration(animDuration);
+        expandAnimation.setDuration(animDuration);
+
+        isExpanding = animationType == EXPANDING;
+        isCollapsing = animationType == COLLAPSING;
+
+        startAnimation(expandAnimation);
+        imageButton.startAnimation(arrowAnimation);
+        isExpanded = animationType == EXPANDING;
+
+    }
+
+    private boolean isExpanding(){
+        return isExpanding;
+    }
+
+    private boolean isCollapsing(){
+        return isCollapsing;
+    }
+
+    private boolean isMoving(){
+        return isExpanding() || isCollapsing();
+    }
+
+    public void setOnExpandedListener(OnExpandedListener listener) {
+        this.listener = listener;
+    }
+
+    public void removeOnExpandedListener(){
+        this.listener = null;
+    }
+
+    private View inflateChild(@LayoutRes int resId) {
+        return inflate(getContext(), resId, null);
+    }
+
+    public View getOuterView() {
+        return outerView;
+    }
+
+    public View getInnerView() {
+        return innerView;
+    }
+
+    @Override
+    public void setOnClickListener(@Nullable OnClickListener l) {
+        if(imageButton != null) imageButton.setOnClickListener(l);
+        super.setOnClickListener(l);
+    }
+
+    private long getAnimDuration() {
+        return animDuration;
+    }
+
+    private void setAnimDuration(long animDuration) {
+        this.animDuration = animDuration;
+    }
+
+    private int reconcileSize(int contentSize, int measureSpec) {
+        final int mode = MeasureSpec.getMode(measureSpec);
+        final int specSize = MeasureSpec.getSize(measureSpec);
+        switch(mode) {
+            case MeasureSpec.EXACTLY:
+                return specSize;
+            case MeasureSpec.AT_MOST:
+                if (contentSize < specSize) {
+                    return contentSize;
+                } else {
+                    log.w("Your content may be cropped!");
+                    return specSize;
+                }
+            case MeasureSpec.UNSPECIFIED:
+            default:
+                return contentSize;
+        }
+    }
+
+    private int atMostSpec(int atMostSpace, int measureSpec) {
+        if (MeasureSpec.getMode(measureSpec) == MeasureSpec.UNSPECIFIED)
+            return measureSpec;
+        else
+            return MeasureSpec.makeMeasureSpec(atMostSpace, MeasureSpec.AT_MOST);
+    }
+
+    private int atMostExactlySpec(int atMostExactlySpace, int measureSpec) {
+        if (MeasureSpec.getMode(measureSpec) == MeasureSpec.UNSPECIFIED)
+            return measureSpec;
+        else
+            return MeasureSpec.makeMeasureSpec(atMostExactlySpace, MeasureSpec.getMode(measureSpec));
+    }
+
+    public void reset() {
+        long anim = getAnimDuration();
+        this.setAnimDuration(0);
+        if (startExpanded) {
+            this.expand();
+        } else {
+            this.collapse();
+        }
+        this.setAnimDuration(anim);
+    }
+
+
+    /**
+     * Interfaces
+     */
+
+    interface OnExpandedListener {
+
+        void onExpandChanged(View v, boolean isExpanded);
+
+    }
+
+}
+
+

app/src/main/java/de/sebse/fuplanner/tools/ui/treeview/DirectoryNodeBinder.java

@@ -0,0 +1,56 @@
+package de.sebse.fuplanner.tools.ui.treeview;
+
+import android.view.View;
+import android.widget.ImageView;
+import android.widget.TextView;
+
+import de.sebse.fuplanner.R;
+import de.sebse.fuplanner.services.KVV.types.Resource;
+
+/**
+ * Created by tlh on 2016/10/1 :)
+ */
+
+public class DirectoryNodeBinder extends TreeViewBinder<DirectoryNodeBinder.ViewHolder> {
+    @Override
+    public ViewHolder provideViewHolder(View itemView) {
+        return new ViewHolder(itemView);
+    }
+
+    @Override
+    public void bindView(ViewHolder holder, int position, TreeNode node) {
+        holder.ivArrow.setRotation(0);
+        holder.ivArrow.setImageResource(R.drawable.ic_keyboard_arrow_right_black_18dp);
+        int rotateDegree = node.isExpand() ? 90 : 0;
+        holder.ivArrow.setRotation(rotateDegree);
+        Resource.Folder dirNode = (Resource.Folder) node.getContent();
+        holder.tvName.setText(dirNode.getTitle());
+        if (node.isLeaf())
+            holder.ivArrow.setVisibility(View.INVISIBLE);
+        else holder.ivArrow.setVisibility(View.VISIBLE);
+    }
+
+    @Override
+    public int getLayoutId() {
+        return R.layout.item_dir;
+    }
+
+    public static class ViewHolder extends TreeViewBinder.ViewHolder {
+        private ImageView ivArrow;
+        private TextView tvName;
+
+        ViewHolder(View rootView) {
+            super(rootView);
+            this.ivArrow = rootView.findViewById(R.id.iv_arrow);
+            this.tvName = rootView.findViewById(R.id.tv_name);
+        }
+
+        public ImageView getIvArrow() {
+            return ivArrow;
+        }
+
+        public TextView getTvName() {
+            return tvName;
+        }
+    }
+}

app/src/main/java/de/sebse/fuplanner/tools/ui/treeview/FileNodeBinder.java

@@ -0,0 +1,39 @@
+package de.sebse.fuplanner.tools.ui.treeview;
+
+import android.view.View;
+import android.widget.TextView;
+
+import de.sebse.fuplanner.R;
+import de.sebse.fuplanner.services.KVV.types.Resource;
+
+/**
+ * Created by tlh on 2016/10/1 :)
+ */
+
+public class FileNodeBinder extends TreeViewBinder<FileNodeBinder.ViewHolder> {
+    @Override
+    public ViewHolder provideViewHolder(View itemView) {
+        return new ViewHolder(itemView);
+    }
+
+    @Override
+    public void bindView(ViewHolder holder, int position, TreeNode node) {
+        Resource.File fileNode = (Resource.File) node.getContent();
+        holder.tvName.setText(fileNode.getTitle());
+    }
+
+    @Override
+    public int getLayoutId() {
+        return R.layout.item_file;
+    }
+
+    public class ViewHolder extends TreeViewBinder.ViewHolder {
+        TextView tvName;
+
+        ViewHolder(View rootView) {
+            super(rootView);
+            this.tvName = rootView.findViewById(R.id.tv_name);
+        }
+
+    }
+}

app/src/main/java/de/sebse/fuplanner/tools/ui/treeview/LayoutItemType.java

@@ -0,0 +1,9 @@
+package de.sebse.fuplanner.tools.ui.treeview;
+
+/**
+ * Created by tlh on 2016/10/1 :)
+ */
+
+public interface LayoutItemType {
+    int getLayoutId();
+}

app/src/main/java/de/sebse/fuplanner/tools/ui/treeview/TreeNode.java

@@ -0,0 +1,147 @@
+package de.sebse.fuplanner.tools.ui.treeview;
+
+import androidx.annotation.NonNull;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Created by tlh on 2016/10/1 :)
+ */
+
+public class TreeNode<T extends LayoutItemType> implements Cloneable {
+    private T content;
+    private TreeNode parent;
+    private List<TreeNode> childList;
+    private boolean isExpand;
+    private boolean isLocked;
+    //the tree high
+    private int height = UNDEFINE;
+
+    private static final int UNDEFINE = -1;
+
+    public TreeNode(@NonNull T content) {
+        this.content = content;
+        this.childList = new ArrayList<>();
+    }
+
+    public int getHeight() {
+        if (isRoot())
+            height = 0;
+        else if (height == UNDEFINE)
+            height = parent.getHeight() + 1;
+        return height;
+    }
+
+    public boolean isRoot() {
+        return parent == null;
+    }
+
+    public boolean isLeaf() {
+        return childList == null || childList.isEmpty();
+    }
+
+    public void setContent(T content) {
+        this.content = content;
+    }
+
+    public T getContent() {
+        return content;
+    }
+
+    public List<TreeNode> getChildList() {
+        return childList;
+    }
+
+    public void setChildList(List<TreeNode> childList) {
+        this.childList.clear();
+        for (TreeNode treeNode : childList) {
+            addChild(treeNode);
+        }
+    }
+
+    public void addChild(TreeNode node) {
+        if (childList == null)
+            childList = new ArrayList<>();
+        childList.add(node);
+        node.parent = this;
+    }
+
+    public void toggle() {
+        isExpand = !isExpand;
+    }
+
+    public void collapse() {
+        if (isExpand) {
+            isExpand = false;
+        }
+    }
+
+    private void collapseAll() {
+        if (childList == null || childList.isEmpty()) {
+            return;
+        }
+        for (TreeNode child : this.childList) {
+            child.collapseAll();
+        }
+    }
+
+    private void expand() {
+        if (!isExpand) {
+            isExpand = true;
+        }
+    }
+
+    private void expandAll() {
+        expand();
+        if (childList == null || childList.isEmpty()) {
+            return;
+        }
+        for (TreeNode child : this.childList) {
+            child.expandAll();
+        }
+    }
+
+    public boolean isExpand() {
+        return isExpand;
+    }
+
+    public void setParent(TreeNode parent) {
+        this.parent = parent;
+    }
+
+    public TreeNode getParent() {
+        return parent;
+    }
+
+    public TreeNode<T> lock() {
+        isLocked = true;
+        return this;
+    }
+
+    public TreeNode<T> unlock() {
+        isLocked = false;
+        return this;
+    }
+
+    public boolean isLocked() {
+        return isLocked;
+    }
+
+    @Override
+    public String toString() {
+        return "TreeNode{" +
+                "content=" + this.content +
+                ", parent=" + (parent == null ? "null" : parent.getContent().toString()) +
+                ", childList=" + (childList == null ? "null" : childList.toString()) +
+                ", isExpand=" + isExpand +
+                '}';
+    }
+
+    @Override
+    protected TreeNode<T> clone() {
+        TreeNode<T> clone = new TreeNode<>(this.content);
+        clone.isExpand = this.isExpand;
+        return clone;
+    }
+}

app/src/main/java/de/sebse/fuplanner/tools/ui/treeview/TreeViewAdapter.java

@@ -0,0 +1,317 @@
+package de.sebse.fuplanner.tools.ui.treeview;
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.recyclerview.widget.DiffUtil;
+import androidx.recyclerview.widget.RecyclerView;
+
+/**
+ * Created by tlh on 2016/10/1 :)
+ */
+public class TreeViewAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
+    private static final String KEY_IS_EXPAND = "IS_EXPAND";
+    private final List<? extends TreeViewBinder> viewBinders;
+    private List<TreeNode> displayNodes;
+    private int padding = 30;
+    private OnTreeNodeListener onTreeNodeListener;
+    private boolean toCollapseChild;
+
+    protected TreeViewAdapter(List<? extends TreeViewBinder> viewBinders) {
+        this(null, viewBinders);
+    }
+
+    private TreeViewAdapter(List<TreeNode> nodes, List<? extends TreeViewBinder> viewBinders) {
+        displayNodes = new ArrayList<>();
+        if (nodes != null)
+            findDisplayNodes(nodes);
+        this.viewBinders = viewBinders;
+    }
+
+    /**
+     * 从nodes的结点中寻找展开了的非叶结点，添加到displayNodes中。
+     *
+     * @param nodes 基准点
+     */
+    private void findDisplayNodes(List<TreeNode> nodes) {
+        for (TreeNode node : nodes) {
+            displayNodes.add(node);
+            if (!node.isLeaf() && node.isExpand())
+                findDisplayNodes(node.getChildList());
+        }
+    }
+
+    @Override
+    public int getItemViewType(int position) {
+        return displayNodes.get(position).getContent().getLayoutId();
+    }
+
+    @Override
+    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
+        View v = LayoutInflater.from(parent.getContext())
+                .inflate(viewType, parent, false);
+        if (viewBinders.size() == 1)
+            return viewBinders.get(0).provideViewHolder(v);
+        for (TreeViewBinder viewBinder : viewBinders) {
+            if (viewBinder.getLayoutId() == viewType)
+                return viewBinder.provideViewHolder(v);
+        }
+        return viewBinders.get(0).provideViewHolder(v);
+    }
+
+    @Override
+    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position, List<Object> payloads) {
+        if (payloads != null && !payloads.isEmpty()) {
+            Bundle b = (Bundle) payloads.get(0);
+            for (String key : b.keySet()) {
+                switch (key) {
+                    case KEY_IS_EXPAND:
+                        if (onTreeNodeListener != null)
+                            onTreeNodeListener.onToggle(b.getBoolean(key), holder);
+                        break;
+                }
+            }
+        }
+        super.onBindViewHolder(holder, position, payloads);
+    }
+
+    @Override
+    public void onBindViewHolder(final RecyclerView.ViewHolder holder, int position) {
+        holder.itemView.setPadding(displayNodes.get(position).getHeight() * padding, 3, 3, 3);
+        holder.itemView.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                TreeNode selectedNode = displayNodes.get(holder.getLayoutPosition());
+                // Prevent multi-click during the short interval.
+                try {
+                    long lastClickTime = (long) holder.itemView.getTag();
+                    if (System.currentTimeMillis() - lastClickTime < 500)
+                        return;
+                } catch (Exception e) {
+                    holder.itemView.setTag(System.currentTimeMillis());
+                }
+                holder.itemView.setTag(System.currentTimeMillis());
+
+                if (onTreeNodeListener != null && onTreeNodeListener.onClick(selectedNode, holder))
+                    return;
+                if (selectedNode.isLeaf())
+                    return;
+                // This TreeNode was locked to click.
+                if (selectedNode.isLocked()) return;
+                boolean isExpand = selectedNode.isExpand();
+                int positionStart = displayNodes.indexOf(selectedNode) + 1;
+                if (!isExpand) {
+                    notifyItemRangeInserted(positionStart, addChildNodes(selectedNode, positionStart));
+                } else {
+                    notifyItemRangeRemoved(positionStart, removeChildNodes(selectedNode, true));
+                }
+            }
+        });
+        for (TreeViewBinder viewBinder : viewBinders) {
+            if (viewBinder.getLayoutId() == displayNodes.get(position).getContent().getLayoutId())
+                viewBinder.bindView(holder, position, displayNodes.get(position));
+        }
+    }
+
+    private int addChildNodes(TreeNode pNode, int startIndex) {
+        List<TreeNode> childList = pNode.getChildList();
+        int addChildCount = 0;
+        for (TreeNode treeNode : childList) {
+            displayNodes.add(startIndex + addChildCount++, treeNode);
+            if (treeNode.isExpand()) {
+                addChildCount += addChildNodes(treeNode, startIndex + addChildCount);
+            }
+        }
+        if (!pNode.isExpand())
+            pNode.toggle();
+        return addChildCount;
+    }
+
+    private int removeChildNodes(TreeNode pNode) {
+        return removeChildNodes(pNode, true);
+    }
+
+    private int removeChildNodes(TreeNode pNode, boolean shouldToggle) {
+        if (pNode.isLeaf())
+            return 0;
+        List<TreeNode> childList = pNode.getChildList();
+        int removeChildCount = childList.size();
+        displayNodes.removeAll(childList);
+        for (TreeNode child : childList) {
+            if (child.isExpand()) {
+                if (toCollapseChild)
+                    child.toggle();
+                removeChildCount += removeChildNodes(child, false);
+            }
+        }
+        if (shouldToggle)
+            pNode.toggle();
+        return removeChildCount;
+    }
+
+    @Override
+    public int getItemCount() {
+        return displayNodes == null ? 0 : displayNodes.size();
+    }
+
+    public void setPadding(int padding) {
+        this.padding = padding;
+    }
+
+    public void ifCollapseChildWhileCollapseParent(boolean toCollapseChild) {
+        this.toCollapseChild = toCollapseChild;
+    }
+
+    public void setOnTreeNodeListener(OnTreeNodeListener onTreeNodeListener) {
+        this.onTreeNodeListener = onTreeNodeListener;
+    }
+
+    public interface OnTreeNodeListener {
+        /**
+         * called when TreeNodes were clicked.
+         * @return weather consume the click event.
+         */
+        boolean onClick(TreeNode node, RecyclerView.ViewHolder holder);
+
+        /**
+         * called when TreeNodes were toggle.
+         * @param isExpand the status of TreeNodes after being toggled.
+         */
+        void onToggle(boolean isExpand, RecyclerView.ViewHolder holder);
+    }
+
+    protected void refresh(List<TreeNode> treeNodes) {
+        displayNodes.clear();
+        findDisplayNodes(treeNodes);
+        notifyDataSetChanged();
+    }
+
+    public Iterator<TreeNode> getDisplayNodesIterator() {
+        return displayNodes.iterator();
+    }
+
+    private void notifyDiff(final List<TreeNode> temp) {
+        DiffUtil.DiffResult diffResult = DiffUtil.calculateDiff(new DiffUtil.Callback() {
+            @Override
+            public int getOldListSize() {
+                return temp.size();
+            }
+
+            @Override
+            public int getNewListSize() {
+                return displayNodes.size();
+            }
+
+            // judge if the same items
+            @Override
+            public boolean areItemsTheSame(int oldItemPosition, int newItemPosition) {
+                return TreeViewAdapter.this.areItemsTheSame(temp.get(oldItemPosition), displayNodes.get(newItemPosition));
+            }
+
+            // if they are the same items, whether the contents has bean changed.
+            @Override
+            public boolean areContentsTheSame(int oldItemPosition, int newItemPosition) {
+                return TreeViewAdapter.this.areContentsTheSame(temp.get(oldItemPosition), displayNodes.get(newItemPosition));
+            }
+
+            @Nullable
+            @Override
+            public Object getChangePayload(int oldItemPosition, int newItemPosition) {
+                return TreeViewAdapter.this.getChangePayload(temp.get(oldItemPosition), displayNodes.get(newItemPosition));
+            }
+        });
+        diffResult.dispatchUpdatesTo(this);
+    }
+
+    private Object getChangePayload(TreeNode oldNode, TreeNode newNode) {
+        Bundle diffBundle = new Bundle();
+        if (newNode.isExpand() != oldNode.isExpand()) {
+            diffBundle.putBoolean(KEY_IS_EXPAND, newNode.isExpand());
+        }
+        if (diffBundle.size() == 0)
+            return null;
+        return diffBundle;
+    }
+
+    // For DiffUtil, if they are the same items, whether the contents has bean changed.
+    private boolean areContentsTheSame(TreeNode oldNode, TreeNode newNode) {
+        return oldNode.getContent() != null && oldNode.getContent().equals(newNode.getContent())
+                && oldNode.isExpand() == newNode.isExpand();
+    }
+
+    // judge if the same item for DiffUtil
+    private boolean areItemsTheSame(TreeNode oldNode, TreeNode newNode) {
+        return oldNode.getContent() != null && oldNode.getContent().equals(newNode.getContent());
+    }
+
+    /**
+     * collapse all root nodes.
+     */
+    public void collapseAll() {
+        // Back up the nodes are displaying.
+        List<TreeNode> temp = backupDisplayNodes();
+        //find all root nodes.
+        List<TreeNode> roots = new ArrayList<>();
+        for (TreeNode displayNode : displayNodes) {
+            if (displayNode.isRoot())
+                roots.add(displayNode);
+        }
+        //Close all root nodes.
+        for (TreeNode root : roots) {
+            if (root.isExpand())
+                removeChildNodes(root);
+        }
+        notifyDiff(temp);
+    }
+
+    @NonNull
+    private List<TreeNode> backupDisplayNodes() {
+        List<TreeNode> temp = new ArrayList<>();
+        for (TreeNode displayNode : displayNodes) {
+            temp.add(displayNode.clone());
+        }
+        return temp;
+    }
+
+    public void collapseNode(TreeNode pNode) {
+        List<TreeNode> temp = backupDisplayNodes();
+        removeChildNodes(pNode);
+        notifyDiff(temp);
+    }
+
+    public void collapseBrotherNode(TreeNode pNode) {
+        List<TreeNode> temp = backupDisplayNodes();
+        if (pNode.isRoot()) {
+            List<TreeNode> roots = new ArrayList<>();
+            for (TreeNode displayNode : displayNodes) {
+                if (displayNode.isRoot())
+                    roots.add(displayNode);
+            }
+            //Close all root nodes.
+            for (TreeNode root : roots) {
+                if (root.isExpand() && !root.equals(pNode))
+                    removeChildNodes(root);
+            }
+        } else {
+            TreeNode parent = pNode.getParent();
+            if (parent == null)
+                return;
+            List<TreeNode> childList = parent.getChildList();
+            for (TreeNode node : childList) {
+                if (node.equals(pNode) || !node.isExpand())
+                    continue;
+                removeChildNodes(node);
+            }
+        }
+        notifyDiff(temp);
+    }
+
+}

app/src/main/java/de/sebse/fuplanner/tools/ui/treeview/TreeViewBinder.java

@@ -0,0 +1,25 @@
+package de.sebse.fuplanner.tools.ui.treeview;
+
+import android.view.View;
+
+import androidx.annotation.IdRes;
+import androidx.recyclerview.widget.RecyclerView;
+
+
+public abstract class TreeViewBinder<VH extends RecyclerView.ViewHolder> implements LayoutItemType {
+    public abstract VH provideViewHolder(View itemView);
+
+    public abstract void bindView(VH holder, int position, TreeNode node);
+
+    public static class ViewHolder extends RecyclerView.ViewHolder {
+        public ViewHolder(View rootView) {
+            super(rootView);
+        }
+
+        protected <T extends View> T findViewById(@IdRes int id) {
+            //noinspection unchecked
+            return (T) itemView.findViewById(id);
+        }
+    }
+
+}

app/src/main/java/de/sebse/fuplanner/tools/ui/weekview/TextColorPicker.java

@@ -1,6 +1,6 @@
 package de.sebse.fuplanner.tools.ui.weekview;
 
-import android.support.annotation.ColorInt;
+import androidx.annotation.ColorInt;
 
 
 

app/src/main/java/de/sebse/fuplanner/tools/ui/weekview/WeekView.java

@@ -9,16 +9,10 @@ import android.graphics.Paint;
 import android.graphics.PointF;
 import android.graphics.Rect;
 import android.graphics.RectF;
-import android.graphics.Region;
 import android.graphics.Typeface;
 import android.graphics.drawable.BitmapDrawable;
 import android.graphics.drawable.Drawable;
 import android.os.Build;
-import android.support.annotation.Nullable;
-import android.support.annotation.RequiresApi;
-import android.support.v4.view.GestureDetectorCompat;
-import android.support.v4.view.ViewCompat;
-import android.support.v4.view.animation.FastOutLinearInInterpolator;
 import android.text.Layout;
 import android.text.SpannableStringBuilder;
 import android.text.StaticLayout;
@@ -45,9 +39,15 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Locale;
 
+import androidx.annotation.Nullable;
+import androidx.annotation.RequiresApi;
+import androidx.core.view.GestureDetectorCompat;
+import androidx.core.view.ViewCompat;
+import androidx.interpolator.view.animation.FastOutLinearInInterpolator;
 import de.sebse.fuplanner.R;
 import de.sebse.fuplanner.tools.ColorRes;
-import de.sebse.fuplanner.tools.DateUtils;
+import de.sebse.fuplanner.tools.UtilsDate;
+import de.sebse.fuplanner.tools.UtilsUi;
 import de.sebse.fuplanner.tools.logging.Logger;
 
 import static de.sebse.fuplanner.tools.ui.weekview.WeekViewUtil.daysBetween;
@@ -62,7 +62,6 @@ import static de.sebse.fuplanner.tools.ui.weekview.WeekViewUtil.today;
  */
 @SuppressWarnings("unused")
 public class WeekView extends View {
-
     private enum Direction {
         NONE, LEFT, RIGHT, VERTICAL
     }
@@ -361,8 +360,8 @@ public class WeekView extends View {
                             selectedTime.set(Calendar.HOUR_OF_DAY, mMinTime);
                             selectedTime.set(Calendar.MINUTE, 0);
                         }
-                        int unroundedMinutes = selectedTime.get(Calendar.MINUTE);
-                        int mod = unroundedMinutes % mNewEventTimeResolutionInMinutes;
+                        int nonRoundedMinutes = selectedTime.get(Calendar.MINUTE);
+                        int mod = nonRoundedMinutes % mNewEventTimeResolutionInMinutes;
                         selectedTime.add(Calendar.MINUTE, mod < Math.ceil(mNewEventTimeResolutionInMinutes / 2) ? -mod : (mNewEventTimeResolutionInMinutes - mod));
 
                         Calendar endTime = (Calendar) selectedTime.clone();
@@ -741,7 +740,8 @@ public class WeekView extends View {
         canvas.drawRect(0, mHeaderHeight + mHeaderRowPadding * 2, mHeaderColumnWidth, getHeight(), mHeaderColumnBackgroundPaint);
 
         // Clip to paint in left column only.
-        canvas.clipRect(0, mHeaderHeight + mHeaderRowPadding * 2, mHeaderColumnWidth, getHeight(), Region.Op.REPLACE);
+        canvas.save();
+        canvas.clipRect(0, mHeaderHeight + mHeaderRowPadding * 2, mHeaderColumnWidth, getHeight());
 
         for (int i = 0; i < getNumberOfPeriods(); i++) {
             // If we are showing half hours (eg. 5:30am), space the times out by half the hour height
@@ -768,6 +768,7 @@ public class WeekView extends View {
             if (top < getHeight())
                 canvas.drawText(time, mTimeTextWidth + mHeaderColumnPadding, top + mTimeTextHeight, mTimeTextPaint);
         }
+        canvas.restore();
     }
 
     private void drawHeaderRowAndEvents(Canvas canvas) {
@@ -852,7 +853,8 @@ public class WeekView extends View {
         }
 
         // Clip to paint events only.
-        canvas.clipRect(mHeaderColumnWidth, mHeaderHeight + mHeaderRowPadding * 2 + mHeaderMarginBottom + mTimeTextHeight / 2, getWidth(), getHeight(), Region.Op.REPLACE);
+        canvas.save();
+        canvas.clipRect(mHeaderColumnWidth, mHeaderHeight + mHeaderRowPadding * 2 + mHeaderMarginBottom + mTimeTextHeight / 2, getWidth(), getHeight());
 
         // Iterate through each day.
         Calendar oldFirstVisibleDay = mFirstVisibleDay;
@@ -954,13 +956,17 @@ public class WeekView extends View {
             // In the next iteration, start from the next day.
             startPixel += mWidthPerDay + mColumnGap;
         }
+        canvas.restore();
 
         // Hide everything in the first cell (top left corner).
-        canvas.clipRect(0, 0, mTimeTextWidth + mHeaderColumnPadding * 2, mHeaderHeight + mHeaderRowPadding * 2, Region.Op.REPLACE);
+        canvas.save();
+        canvas.clipRect(0, 0, mTimeTextWidth + mHeaderColumnPadding * 2, mHeaderHeight + mHeaderRowPadding * 2);
         canvas.drawRect(0, 0, mTimeTextWidth + mHeaderColumnPadding * 2, mHeaderHeight + mHeaderRowPadding * 2, mHeaderBackgroundPaint);
+        canvas.restore();
 
         // Clip to paint header row only.
-        canvas.clipRect(mHeaderColumnWidth, 0, getWidth(), mHeaderHeight + mHeaderRowPadding * 2, Region.Op.REPLACE);
+        canvas.save();
+        canvas.clipRect(mHeaderColumnWidth, 0, getWidth(), mHeaderHeight + mHeaderRowPadding * 2);
 
         // Draw the header background.
         canvas.drawRect(0, 0, getWidth(), mHeaderHeight + mHeaderRowPadding * 2, mHeaderBackgroundPaint);
@@ -981,10 +987,11 @@ public class WeekView extends View {
             String dayLabel = getDateTimeInterpreter().interpretDate(day);
             if (dayLabel == null)
                 throw new IllegalStateException("A DateTimeInterpreter must not return null date");
-            canvas.drawText(dayLabel, startPixel + mWidthPerDay / 2, mHeaderTextHeight + mHeaderRowPadding, isToday ? mTodayHeaderTextPaint : mHeaderTextPaint);
+            canvas.drawText(dayLabel, startPixel + mWidthPerDay / 2, mHeaderTextHeight + mHeaderRowPadding+ UtilsUi.convertPixelsToDp(40, mContext), isToday ? mTodayHeaderTextPaint : mHeaderTextPaint);
             drawAllDayEvents(day, startPixel, canvas);
             startPixel += mWidthPerDay + mColumnGap;
         }
+        canvas.restore();
 
     }
 
@@ -1253,8 +1260,8 @@ public class WeekView extends View {
      */
     private class EventRect {
         public WeekViewEvent event;
-        public WeekViewEvent originalEvent;
-        public RectF rectF;
+        WeekViewEvent originalEvent;
+        RectF rectF;
         public float left;
         public float width;
         public float top;
@@ -1645,7 +1652,7 @@ public class WeekView extends View {
                 @Override
                 public String interpretDate(Calendar date) {
                     try {
-                        return DateUtils.getModifiedDate(getContext(), date.getTimeInMillis(), "EEE dd.M").toUpperCase();
+                        return UtilsDate.getModifiedDate(getContext(), date.getTimeInMillis(), "EEE dd.M").toUpperCase();
                     } catch (Exception e) {
                         e.printStackTrace();
                         return "";
@@ -2414,7 +2421,7 @@ public class WeekView extends View {
     /**
      * Set the scroll duration
      *
-     * @param scrollDuration the new scrollDuraction
+     * @param scrollDuration the new scrollDuration
      */
     public void setScrollDuration(int scrollDuration) {
         mScrollDuration = scrollDuration;
@@ -2518,7 +2525,7 @@ public class WeekView extends View {
         // Check after call of mGestureDetector, so mCurrentFlingDirection and mCurrentScrollDirection are set.
         if (event.getAction() == MotionEvent.ACTION_UP && !mIsZooming && mCurrentFlingDirection == Direction.NONE) {
             if (mCurrentScrollDirection == Direction.RIGHT || mCurrentScrollDirection == Direction.LEFT) {
-                goToNearestOrigin();
+                performClick();
             }
             mCurrentScrollDirection = Direction.NONE;
         }
@@ -2526,6 +2533,13 @@ public class WeekView extends View {
         return val;
     }
 
+    @Override
+    public boolean performClick() {
+        super.performClick();
+        goToNearestOrigin();
+        return true;
+    }
+
     private void goToNearestOrigin() {
         double leftDays = mCurrentOrigin.x / (mWidthPerDay + mColumnGap);
 

app/src/main/java/de/sebse/fuplanner/tools/ui/weekview/WeekViewEvent.java

@@ -76,7 +76,7 @@ public class WeekViewEvent {
      * @param allDay    Is the event an all day event.
      * @param shader    the Shader of the event rectangle
      */
-    public WeekViewEvent(String id, String name, String location, Calendar startTime, Calendar endTime, boolean allDay, Shader shader) {
+    private WeekViewEvent(String id, String name, String location, Calendar startTime, Calendar endTime, boolean allDay, Shader shader) {
         this.mId = id;
         this.mName = name;
         this.mLocation = location;
@@ -96,7 +96,7 @@ public class WeekViewEvent {
      * @param endTime   The time when the event ends.
      * @param allDay    Is the event an all day event
      */
-    public WeekViewEvent(String id, String name, String location, Calendar startTime, Calendar endTime, boolean allDay) {
+    private WeekViewEvent(String id, String name, String location, Calendar startTime, Calendar endTime, boolean allDay) {
         this(id, name, location, startTime, endTime, allDay, null);
     }
 

app/src/main/java/de/sebse/fuplanner/tools/ui/weekview/WeekViewUtil.java

@@ -5,7 +5,7 @@ import java.util.Calendar;
 /**
  * Created by jesse on 6/02/2016.
  */
-public class WeekViewUtil {
+class WeekViewUtil {
 
 
     /////////////////////////////////////////////////////////////////