Fixed crash

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

@@ -885,29 +885,4 @@ public class ActivityView extends ActivityBilling implements FragmentManager.OnB
                 }.load(this, args);
             }
     }
-
-    void setMessages(PagedList<TupleMessageEx> messages) {
-        this.messages = messages;
-    }
-
-    public String[] getPrevNext(String thread) {
-        boolean found = false;
-        TupleMessageEx prev = null;
-        TupleMessageEx next = null;
-        for (int i = 0; i < messages.size(); i++) {
-            TupleMessageEx item = messages.get(i);
-            if (item == null)
-                continue;
-            if (found) {
-                next = item;
-                messages.loadAround(i);
-                break;
-            }
-            if (thread.equals(item.thread))
-                found = true;
-            else
-                prev = item;
-        }
-        return new String[]{prev == null ? null : prev.thread, next == null ? null : next.thread};
-    }
 }

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

@@ -57,6 +57,7 @@ import androidx.fragment.app.FragmentTransaction;
 import androidx.lifecycle.Lifecycle;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.Observer;
+import androidx.lifecycle.ViewModelProviders;
 import androidx.localbroadcastmanager.content.LocalBroadcastManager;
 import androidx.paging.LivePagedListBuilder;
 import androidx.paging.PagedList;
@@ -585,7 +586,8 @@ public class FragmentMessages extends FragmentEx {
 
         // Compose FAB
         if (viewType == AdapterMessage.ViewType.THREAD) {
-            String[] pn = ((ActivityView) getActivity()).getPrevNext(thread);
+            ViewModelMessages model = ViewModelProviders.of(getActivity()).get(ViewModelMessages.class);
+            String[] pn = model.getPrevNext(thread);
 
             fabPrev.setTag(pn[0]);
             fabNext.setTag(pn[1]);
@@ -854,8 +856,10 @@ public class FragmentMessages extends FragmentEx {
                     return;
                 }
 
-                if (viewType != AdapterMessage.ViewType.THREAD)
+                if (viewType != AdapterMessage.ViewType.THREAD) {
-                    ((ActivityView) getActivity()).setMessages(messages);
+                    ViewModelMessages model = ViewModelProviders.of(getActivity()).get(ViewModelMessages.class);
+                    model.setMessages(messages);
+                }
 
                 if (viewType == AdapterMessage.ViewType.THREAD && autoExpand) {
                     autoExpand = false;