Fixed changing view model type

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

@@ -71,7 +71,6 @@ import androidx.fragment.app.FragmentManager;
 import androidx.fragment.app.FragmentTransaction;
 import androidx.lifecycle.Lifecycle;
 import androidx.lifecycle.LifecycleOwner;
-import androidx.lifecycle.LiveData;
 import androidx.lifecycle.Observer;
 import androidx.lifecycle.ViewModelProviders;
 import androidx.localbroadcastmanager.content.LocalBroadcastManager;
@@ -2620,10 +2619,15 @@ public class FragmentMessages extends FragmentBase {
 
         ViewModelMessages model = ViewModelProviders.of(getActivity()).get(ViewModelMessages.class);
 
-        LiveData<PagedList<TupleMessageEx>> liveMessages = model.getPagedList(
+        ViewModelMessages.Model vmodel = model.getModel(
                 getContext(), getViewLifecycleOwner(),
-                viewType, account, folder, thread, id, query, server,
-                new BoundaryCallbackMessages.IBoundaryCallbackMessages() {
+                viewType, account, folder, thread, id, query, server);
+
+        vmodel.setCallback(callback);
+        vmodel.setObserver(getViewLifecycleOwner(), observer);
+    }
+
+    private BoundaryCallbackMessages.IBoundaryCallbackMessages callback = new BoundaryCallbackMessages.IBoundaryCallbackMessages() {
         @Override
         public void onLoading() {
             loading = true;
@@ -2654,9 +2658,9 @@ public class FragmentMessages extends FragmentBase {
                             .create()
                             .show();
         }
-                });
+    };
 
-        liveMessages.observe(getViewLifecycleOwner(), new Observer<PagedList<TupleMessageEx>>() {
+    private Observer<PagedList<TupleMessageEx>> observer = new Observer<PagedList<TupleMessageEx>>() {
         @Override
         public void onChanged(@Nullable PagedList<TupleMessageEx> messages) {
             if (messages == null)
@@ -2690,8 +2694,7 @@ public class FragmentMessages extends FragmentBase {
                 grpReady.setVisibility(View.VISIBLE);
             }
         }
-        });
-    }
+    };
 
     private boolean handleThreadActions(@NonNull PagedList<TupleMessageEx> messages) {
         // Auto close / next

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

@@ -52,12 +52,11 @@ public class ViewModelMessages extends ViewModel {
     private static final int LOCAL_PAGE_SIZE = 100;
     private static final int REMOTE_PAGE_SIZE = 10;
 
-    LiveData<PagedList<TupleMessageEx>> getPagedList(
-            Context context, LifecycleOwner owner,
+    Model getModel(
+            Context context, final LifecycleOwner owner,
             final AdapterMessage.ViewType viewType,
             long account, long folder, String thread, long id,
-            String query, boolean server,
-            BoundaryCallbackMessages.IBoundaryCallbackMessages callback) {
+            String query, boolean server) {
 
         Args args = new Args(context, account, folder, thread, id, query, server);
         Log.i("Get model " + viewType + " " + args);
@@ -67,8 +66,10 @@ public class ViewModelMessages extends ViewModel {
         if (model == null || !model.args.equals(args)) {
             Log.i("Creating model");
 
-            if (model != null)
+            if (model != null) {
                 model.clear();
+                model.list.removeObservers(owner);
+            }
 
             DB db = DB.getInstance(context);
 
@@ -168,9 +169,6 @@ public class ViewModelMessages extends ViewModel {
                 });
         }
 
-        if (model.boundary != null)
-            model.boundary.setCallback(callback);
-
         if (viewType == AdapterMessage.ViewType.UNIFIED) {
             remove(AdapterMessage.ViewType.FOLDER);
             remove(AdapterMessage.ViewType.SEARCH);
@@ -182,7 +180,7 @@ public class ViewModelMessages extends ViewModel {
         Log.i("Returning model=" + viewType);
         dump();
 
-        return model.list;
+        return model;
     }
 
     @Override
@@ -193,11 +191,9 @@ public class ViewModelMessages extends ViewModel {
 
     private void remove(AdapterMessage.ViewType viewType) {
         Model model = models.get(viewType);
-        if (model != null) {
-            model.clear();
+        if (model != null)
             models.remove(viewType);
     }
-    }
 
     void observePrevNext(LifecycleOwner owner, final long id, final IPrevNext intf) {
         Log.i("Observe prev/next model=" + last);
@@ -321,7 +317,7 @@ public class ViewModelMessages extends ViewModel {
         Log.i("Current models=" + TextUtils.join(", ", models.keySet()));
     }
 
-    private class Model {
+    class Model {
         private Args args;
         private LiveData<PagedList<TupleMessageEx>> list;
         private BoundaryCallbackMessages boundary;
@@ -332,6 +328,15 @@ public class ViewModelMessages extends ViewModel {
             this.boundary = boundary;
         }
 
+        void setCallback(BoundaryCallbackMessages.IBoundaryCallbackMessages callback) {
+            if (boundary != null)
+                boundary.setCallback(callback);
+        }
+
+        void setObserver(LifecycleOwner owner, @NonNull Observer<PagedList<TupleMessageEx>> observer) {
+            list.observe(owner, observer);
+        }
+
         private void clear() {
             if (this.boundary != null)
                 this.boundary.clear();