Check if answers defined

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

@@ -63,6 +63,7 @@ import android.widget.TextView;
 import android.widget.Toast;
 
 import com.google.android.material.bottomnavigation.BottomNavigationView;
+import com.google.android.material.snackbar.Snackbar;
 
 import org.xml.sax.XMLReader;
 
@@ -90,6 +91,8 @@ import androidx.annotation.Nullable;
 import androidx.appcompat.widget.PopupMenu;
 import androidx.constraintlayout.widget.Group;
 import androidx.core.content.ContextCompat;
+import androidx.fragment.app.FragmentManager;
+import androidx.fragment.app.FragmentTransaction;
 import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.Observer;
 import androidx.localbroadcastmanager.content.LocalBroadcastManager;
@@ -103,6 +106,7 @@ import androidx.recyclerview.widget.RecyclerView;
 public class AdapterMessage extends PagedListAdapter<TupleMessageEx, AdapterMessage.ViewHolder> {
     private Context context;
     private LifecycleOwner owner;
+    private FragmentManager fragmentManager;
     private ViewType viewType;
     private IProperties properties;
 
@@ -906,6 +910,21 @@ public class AdapterMessage extends PagedListAdapter<TupleMessageEx, AdapterMess
             db.answer().liveAnswers().observe(owner, new Observer<List<EntityAnswer>>() {
                 @Override
                 public void onChanged(List<EntityAnswer> answers) {
+                    if (answers == null || answers.size() == 0) {
+                        Snackbar snackbar = Snackbar.make(
+                                itemView,
+                                context.getString(R.string.title_no_answers),
+                                Snackbar.LENGTH_LONG);
+                        snackbar.setAction(R.string.title_fix, new View.OnClickListener() {
+                            @Override
+                            public void onClick(View v) {
+                                FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
+                                fragmentTransaction.replace(R.id.content_frame, new FragmentAnswers()).addToBackStack("answers");
+                                fragmentTransaction.commit();
+                            }
+                        });
+                        snackbar.show();
+                    } else {
                         final Collator collator = Collator.getInstance(Locale.getDefault());
                         collator.setStrength(Collator.SECONDARY); // Case insensitive, process accents etc
 
@@ -940,6 +959,7 @@ public class AdapterMessage extends PagedListAdapter<TupleMessageEx, AdapterMess
                         });
 
                         popupMenu.show();
+                    }
 
                     db.answer().liveAnswers().removeObservers(owner);
                 }
@@ -1345,10 +1365,11 @@ public class AdapterMessage extends PagedListAdapter<TupleMessageEx, AdapterMess
         }
     }
 
-    AdapterMessage(Context context, LifecycleOwner owner, ViewType viewType, IProperties properties) {
+    AdapterMessage(Context context, LifecycleOwner owner, FragmentManager fragmentManager, ViewType viewType, IProperties properties) {
         super(DIFF_CALLBACK);
         this.context = context;
         this.owner = owner;
+        this.fragmentManager = fragmentManager;
         this.viewType = viewType;
         this.properties = properties;
 

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

@@ -190,7 +190,7 @@ public class FragmentMessages extends FragmentEx {
         LinearLayoutManager llm = new LinearLayoutManager(getContext());
         rvMessage.setLayoutManager(llm);
 
-        adapter = new AdapterMessage(getContext(), getViewLifecycleOwner(), viewType, new AdapterMessage.IProperties() {
+        adapter = new AdapterMessage(getContext(), getViewLifecycleOwner(), getFragmentManager(), viewType, new AdapterMessage.IProperties() {
             @Override
             public void setExpanded(long id, boolean expand) {
                 if (expand) {