Lifecycle aware back listener

app/src/main/java/eu/faircode/email/ActivityBase.java

@@ -35,10 +35,15 @@ import java.util.List;
 import androidx.annotation.Nullable;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.fragment.app.Fragment;
+import androidx.lifecycle.Lifecycle;
+import androidx.lifecycle.LifecycleObserver;
+import androidx.lifecycle.LifecycleOwner;
+import androidx.lifecycle.OnLifecycleEvent;
 import androidx.preference.PreferenceManager;
 
 abstract class ActivityBase extends AppCompatActivity implements SharedPreferences.OnSharedPreferenceChangeListener {
     private boolean contacts;
+    private List<IBackPressedListener> backPressedListeners = new ArrayList<>();
 
     @Override
     protected void attachBaseContext(Context base) {
@@ -148,16 +153,19 @@ abstract class ActivityBase extends AppCompatActivity implements SharedPreferenc
         return findViewById(android.R.id.content);
     }
 
-    private List<IBackPressedListener> backPressedListeners = new ArrayList<>();
+    void addBackPressedListener(final IBackPressedListener listener, LifecycleOwner owner) {
+        owner.getLifecycle().addObserver(new LifecycleObserver() {
+            @OnLifecycleEvent(Lifecycle.Event.ON_DESTROY)
+            public void onDestroyed() {
+                Log.i("Removing back listener=" + listener);
+                backPressedListeners.remove(listener);
+            }
+        });
 
-    public void addBackPressedListener(IBackPressedListener listener) {
+        Log.i("Adding back listener=" + listener);
         backPressedListeners.add(listener);
     }
 
-    public void removeBackPressedListener(IBackPressedListener listener) {
-        backPressedListeners.remove(listener);
-    }
-
     @Override
     public void onBackPressed() {
         for (IBackPressedListener listener : backPressedListeners)

app/src/main/java/eu/faircode/email/FragmentBase.java

@@ -148,4 +148,8 @@ public class FragmentBase extends Fragment {
             return false;
         return activity.hasPermission(name);
     }
+
+    void addBackPressedListener(ActivityBase.IBackPressedListener listener) {
+        ((ActivityBase) getActivity()).addBackPressedListener(listener, getViewLifecycleOwner());
+    }
 }

app/src/main/java/eu/faircode/email/FragmentCompose.java

@@ -406,8 +406,7 @@ public class FragmentCompose extends FragmentBase {
             }
         });
 
-        ((ActivityBase) getActivity()).addBackPressedListener(onBackPressedListener);
-
+        addBackPressedListener(onBackPressedListener);
 
         // Initialize
         setSubtitle(R.string.title_compose);
@@ -613,8 +612,6 @@ public class FragmentCompose extends FragmentBase {
         if (pgpService != null)
             pgpService.unbindFromService();
 
-        ((ActivityBase) getActivity()).removeBackPressedListener(onBackPressedListener);
-
         super.onDestroyView();
     }
 

app/src/main/java/eu/faircode/email/FragmentMessages.java

@@ -511,7 +511,7 @@ public class FragmentMessages extends FragmentBase {
             }
         });
 
-        ((ActivityBase) getActivity()).addBackPressedListener(onBackPressedListener);
+        addBackPressedListener(onBackPressedListener);
 
         // Initialize
         swipeRefresh.setEnabled(false);
@@ -1607,12 +1607,6 @@ public class FragmentMessages extends FragmentBase {
         }.execute(FragmentMessages.this, args, "messages:move");
     }
 
-    @Override
-    public void onDestroyView() {
-        ((ActivityBase) getActivity()).removeBackPressedListener(onBackPressedListener);
-        super.onDestroyView();
-    }
-
     @Override
     public void onSaveInstanceState(Bundle outState) {
         outState.putString("fair:searching", searching);