Back Button Implemented! Finally! Finally! Finally!

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

@@ -2,6 +2,7 @@ package de.sebse.fuplanner;
 
 import android.content.Intent;
 import android.os.Bundle;
+import android.os.Handler;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.View;
@@ -11,6 +12,8 @@ import android.widget.Toast;
 import com.android.volley.NetworkResponse;
 import com.google.android.material.navigation.NavigationView;
 
+import org.jetbrains.annotations.NotNull;
+
 import java.util.HashMap;
 import java.util.Iterator;
 
@@ -43,6 +46,7 @@ import de.sebse.fuplanner.services.KVV.types.LoginToken;
 import de.sebse.fuplanner.services.KVV.types.Modules;
 import de.sebse.fuplanner.tools.MainActivityListener;
 import de.sebse.fuplanner.tools.NewAsyncQueue;
+import de.sebse.fuplanner.tools.Regex;
 import de.sebse.fuplanner.tools.RequestPermissionsResultListener;
 import de.sebse.fuplanner.tools.logging.Logger;
 import de.sebse.fuplanner.tools.network.NetworkCallback;
@@ -68,6 +72,7 @@ public class MainActivity extends AppCompatActivity
 
     private static final String ARG_FRAGMENT_PAGE = "fragment_page";
     private static final String ARG_FRAGMENT_STATUS = "fragment_status";
+    private static final int DOUBLE_CLICK_TO_EXIT_MILLIS = 200;
 
     private FragmentManager mFragmentManager;
     private GoogleAuth mGoogleAuth;
@@ -75,12 +80,14 @@ public class MainActivity extends AppCompatActivity
     private final Logger log = new Logger(this);
     private NavigationView mNavigationView;
 
-    private int fragmentPage = FRAGMENT_NONE;
+    private int mFragmentPage = FRAGMENT_NONE;
-    private String fragmentData = "";
+    @NotNull
+    private String mFragmentData = "";
     private CanteenBrowser mCanteenBrowser;
     private final HashMap<String, RequestPermissionsResultListener> permissionListeners = new HashMap<>();
     private boolean mOfflineBanner;
     private final NewAsyncQueue mQueue = new NewAsyncQueue();
+    private long mDoubleBackToExitPressedOnce = 0;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -110,24 +117,51 @@ public class MainActivity extends AppCompatActivity
             desiredPage = FRAGMENT_LOGIN;
             desiredData = "";
         }
+        log.d("desired", desiredPage, desiredData);
         updateNavigation();
         changeFragment(desiredPage, desiredData);
     }
 
     @Override
     public void onBackPressed() {
+        if (mDoubleBackToExitPressedOnce + DOUBLE_CLICK_TO_EXIT_MILLIS > System.currentTimeMillis()) {
+            super.onBackPressed();
+            return;
+        }
+
         DrawerLayout drawer = findViewById(R.id.drawer_layout);
         if (drawer.isDrawerOpen(GravityCompat.START)) {
             drawer.closeDrawer(GravityCompat.START);
         } else {
-            super.onBackPressed();
+            if (mFragmentPage == FRAGMENT_MODULES_DETAILS) {
+                ModDetailFragment fragment = (ModDetailFragment) mFragmentManager.findFragmentByTag(String.valueOf(FRAGMENT_MODULES_DETAILS));
+                if (fragment != null && fragment.isVisible() && Regex.has("\\.[1-9][0-9]*", fragment.getData())) {
+                    fragment.gotoFragmentPart(0, -1);
+                } else {
+                    changeFragment(FRAGMENT_MODULES);
+                }
+            } else if (mFragmentPage == FRAGMENT_CANTEENS_DETAILS) {
+                DaySwitcherFragment fragment = (DaySwitcherFragment) mFragmentManager.findFragmentByTag(String.valueOf(FRAGMENT_CANTEENS_DETAILS));
+                if (fragment != null && fragment.isVisible() && Regex.has("\\.[1-9][0-9]*", fragment.getData())) {
+                    fragment.gotoFragmentPart(0);
+                } else {
+                    changeFragment(FRAGMENT_CANTEENS);
+                }
+            } else if (getKVV().account().isLoggedIn() && mFragmentPage != getDefaultFragmentAfterLogin()) {
+                changeFragment(getDefaultFragmentAfterLogin());
+            } else if (!getKVV().account().isLoggedIn() && mFragmentPage != FRAGMENT_LOGIN) {
+                changeFragment(FRAGMENT_LOGIN);
+            } else {
+                mDoubleBackToExitPressedOnce = System.currentTimeMillis();
+                showToast(R.string.back_to_exit);
+            }
         }
     }
 
     @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 (mFragmentPage == FRAGMENT_SCHEDULE) {
             getMenuInflater().inflate(R.menu.options_schedule, menu);
             return true;
         }
@@ -217,13 +251,15 @@ public class MainActivity extends AppCompatActivity
 
     @Override
     protected void onSaveInstanceState(Bundle savedInstanceState) {
-        if (fragmentPage != FRAGMENT_STARTUP && fragmentPage != FRAGMENT_NONE && fragmentPage != FRAGMENT_LOGIN) {
+        if (mFragmentPage != FRAGMENT_STARTUP && mFragmentPage != FRAGMENT_NONE && mFragmentPage != FRAGMENT_LOGIN) {
-            Fragment fragment = mFragmentManager.findFragmentByTag(String.valueOf(fragmentPage));
+            Fragment fragment = mFragmentManager.findFragmentByTag(String.valueOf(mFragmentPage));
-            savedInstanceState.putInt(ARG_FRAGMENT_PAGE, fragmentPage);
+            savedInstanceState.putInt(ARG_FRAGMENT_PAGE, mFragmentPage);
             if (fragment instanceof ModDetailFragment) {
                 savedInstanceState.putString(ARG_FRAGMENT_STATUS, ((ModDetailFragment) fragment).getData());
+            } else if (fragment instanceof DaySwitcherFragment) {
+                savedInstanceState.putString(ARG_FRAGMENT_STATUS, ((DaySwitcherFragment) fragment).getData());
             } else {
-                savedInstanceState.putString(ARG_FRAGMENT_STATUS, fragmentData);
+                savedInstanceState.putString(ARG_FRAGMENT_STATUS, mFragmentData);
             }
         }
         super.onSaveInstanceState(savedInstanceState);
@@ -319,7 +355,7 @@ public class MainActivity extends AppCompatActivity
                 fragment = ScheduleFragment.newInstance();
                 break;
             case FRAGMENT_CANTEENS_DETAILS:
-                fragment = DaySwitcherFragment.newInstance(Integer.parseInt(newData));
+                fragment = DaySwitcherFragment.newInstance(newData);
                 break;
             case FRAGMENT_CANTEENS:
                 fragment = CanteensFragment.newInstance();
@@ -345,8 +381,8 @@ public class MainActivity extends AppCompatActivity
             findViewById(R.id.app_bar_include).setVisibility(View.VISIBLE);
         }
 
-        this.fragmentPage = newFragment;
+        this.mFragmentPage = newFragment;
-        this.fragmentData = newData;
+        this.mFragmentData = newData;
 
         invalidateOptionsMenu();
     }
@@ -367,9 +403,9 @@ public class MainActivity extends AppCompatActivity
 
     private void setNavigationSelection() {
         MenuItem item;
-        switch (fragmentPage) {
+        switch (mFragmentPage) {
             case FRAGMENT_MODULES_DETAILS:
-                getKVV().modules().list().find(fragmentData, success -> {
+                getKVV().modules().list().find(mFragmentData, success -> {
                     int size = mNavigationView.getMenu().size();
                     //noinspection ConstantConditions
                     String title = success == null ? null : success.title;
@@ -391,7 +427,7 @@ public class MainActivity extends AppCompatActivity
             case FRAGMENT_CANTEENS_DETAILS:
                 getCanteenBrowser().getCanteens(success -> {
                     int size = mNavigationView.getMenu().size();
-                    Canteen canteen = success.getCanteen(Integer.parseInt(fragmentData));
+                    Canteen canteen = success.getCanteen(Integer.parseInt(mFragmentData));
                     //noinspection ConstantConditions
                     String title = canteen == null ? null : canteen.getName();
                     for (int k = 0; k < size; k++) {

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

@@ -31,10 +31,12 @@ public class DaySwitcherFragment extends Fragment implements DaySwitcherListener
 
     // Parameters
     private int mCanteenId;
+    private String mPageRestoreRequest = null;
 
     private MainActivityListener mListener;
     private final Logger log = new Logger(this);
     private DaySwitcherAdapter adapterViewPager;
+    private ViewPager mViewPager;
 
     public DaySwitcherFragment() {
         // Required empty public constructor
@@ -47,10 +49,14 @@ public class DaySwitcherFragment extends Fragment implements DaySwitcherListener
      * @param canteenId Canteen id in canteens list.
      * @return A new instance of fragment DaySwitcherFragment.
      */
-    public static Fragment newInstance(int canteenId) {
+    public static Fragment newInstance(String canteenId) {
         DaySwitcherFragment fragment = new DaySwitcherFragment();
         Bundle args = new Bundle();
-        args.putInt(ARG_POSITION, canteenId);
+        if (!canteenId.contains("."))
+            args.putString(ARG_POSITION, canteenId+".0");
+        else
+            args.putString(ARG_POSITION, canteenId);
+
         fragment.setArguments(args);
         return fragment;
     }
@@ -59,7 +65,15 @@ public class DaySwitcherFragment extends Fragment implements DaySwitcherListener
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         if (getArguments() != null) {
-            mCanteenId = getArguments().getInt(ARG_POSITION);
+            String canteenId = getArguments().getString(ARG_POSITION);
+            if (!canteenId.contains(".")) {
+                mCanteenId = Integer.parseInt(canteenId);
+                mPageRestoreRequest = null;
+            } else {
+                String[] split = canteenId.split("\\.", 2);
+                mCanteenId = Integer.parseInt(split[0]);
+                mPageRestoreRequest = split[1];
+            }
         }
         if (mListener != null) {
             mListener.onTitleTextChange(R.string.canteens);
@@ -77,10 +91,10 @@ public class DaySwitcherFragment extends Fragment implements DaySwitcherListener
         // Inflate the layout for this fragment
         View v = inflater.inflate(R.layout.fragment_mod_detail, container, false);
 
-        ViewPager mViewPager = v.findViewById(R.id.vpPager);
+        mViewPager = v.findViewById(R.id.vpPager);
         adapterViewPager = new DaySwitcherAdapter(getChildFragmentManager());
         mViewPager.setAdapter(adapterViewPager);
-
+        applyPageRequest();
         refresh();
 
         return v;
@@ -114,8 +128,10 @@ public class DaySwitcherFragment extends Fragment implements DaySwitcherListener
                 Canteen canteen = canteens.getCanteen(mCanteenId);
                 canteen.cleanUpDays();
                 adapterViewPager.setModule(canteen);
+                applyPageRequest();
                 browser.getCanteen(canteen, success -> {
                     adapterViewPager.setModule();
+                    applyPageRequest();
                     if (callback != null)
                         callback.onResponse(success);
                 }, error -> {
@@ -136,4 +152,20 @@ public class DaySwitcherFragment extends Fragment implements DaySwitcherListener
         refresh(true, callback, errorCallback);
     }
 
+    public void gotoFragmentPart(int part) {
+        mViewPager.setCurrentItem(part, true);
+    }
+
+    public String getData() {
+        return mCanteenId+"."+mViewPager.getCurrentItem();
+    }
+
+    private void applyPageRequest() {
+        if (mPageRestoreRequest != null) {
+            int request = Integer.parseInt(mPageRestoreRequest);
+            mViewPager.setCurrentItem(request);
+            if (request == mViewPager.getCurrentItem())
+                mPageRestoreRequest = null;
+        }
+    }
 }

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

@@ -48,7 +48,7 @@ public class ModDetailFragment extends Fragment implements ModDetailListener {
         ModDetailFragment fragment = new ModDetailFragment();
         Bundle args = new Bundle();
         if (!itemPosition.contains("."))
-            args.putString(ARG_POSITION, itemPosition+"."+0);
+            args.putString(ARG_POSITION, itemPosition+".0");
         else
             args.putString(ARG_POSITION, itemPosition);
 

app/src/main/res/values-de/strings.xml

@@ -81,4 +81,5 @@
     <string name="news">Neuigkeiten</string>
     <string name="update_news">Update-News</string>
     <string name="tricks">Tipps/Tricks</string>
+    <string name="back_to_exit">Klicke ZURÜCK erneut zum Beenden!</string>
 </resources>

app/src/main/res/values/strings.xml

@@ -89,4 +89,5 @@
     <string name="news">News</string>
     <string name="update_news">Update News</string>
     <string name="tricks">Tips/Tricks</string>
+    <string name="back_to_exit">Please click BACK again to exit!</string>
 </resources>