Animate mess menu transitions

app/src/main/java/app/insti/adapter/MessMenuAdapter.java

@@ -19,6 +19,7 @@ public class MessMenuAdapter extends RecyclerView.Adapter<MessMenuAdapter.ViewHo
 
     public MessMenuAdapter(List<MessMenu> messMenus) {
         this.messMenus = messMenus;
+        this.setHasStableIds(true);
     }
 
     @NonNull
@@ -42,11 +43,20 @@ public class MessMenuAdapter extends RecyclerView.Adapter<MessMenuAdapter.ViewHo
         holder.dinner.setText(messMenu.getDinner());
     }
 
+    @Override
+    public long getItemId(int position) {
+        return messMenus.get(position).getMealID().hashCode();
+    }
+
     @Override
     public int getItemCount() {
         return messMenus.size();
     }
 
+    public void setMenu(List<MessMenu> menus) {
+        messMenus = menus;
+    }
+
     private String generateDayString(int day) {
         switch (day) {
             case 1:

app/src/main/java/app/insti/fragment/MessMenuFragment.java

@@ -37,6 +37,7 @@ import retrofit2.Response;
  */
 public class MessMenuFragment extends BaseFragment {
 
+    private MessMenuAdapter messMenuAdapter;
     private RecyclerView messMenuRecyclerView;
     private SwipeRefreshLayout messMenuSwipeRefreshLayout;
     private Spinner hostelSpinner;
@@ -163,14 +164,19 @@ public class MessMenuFragment extends BaseFragment {
             }
         }
 
-        final MessMenuAdapter messMenuAdapter = new MessMenuAdapter(sortedMenus);
         getActivityBuffer().safely(new ActivityBuffer.IRunnable() {
             @Override
             public void run(Activity pActivity) {
                 try {
-                    messMenuRecyclerView = getActivity().findViewById(R.id.mess_menu_recycler_view);
-                    messMenuRecyclerView.setAdapter(messMenuAdapter);
-                    messMenuRecyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
+                    if (messMenuAdapter == null) {
+                        messMenuAdapter = new MessMenuAdapter(sortedMenus);
+                        messMenuRecyclerView = getActivity().findViewById(R.id.mess_menu_recycler_view);
+                        messMenuRecyclerView.setAdapter(messMenuAdapter);
+                        messMenuRecyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
+                    } else {
+                        messMenuAdapter.setMenu(sortedMenus);
+                        messMenuAdapter.notifyDataSetChanged();
+                    }
                 } catch (NullPointerException e) {
                     e.printStackTrace();
                 }