Simplify empty view handling on recycler views

app/src/main/java/de/danoeh/antennapod/fragment/AllEpisodesFragment.java

@@ -51,6 +51,7 @@ import de.danoeh.antennapod.core.util.FeedItemUtil;
 import de.danoeh.antennapod.core.util.LongList;
 import de.danoeh.antennapod.menuhandler.FeedItemMenuHandler;
 import de.danoeh.antennapod.menuhandler.MenuItemUtils;
+import de.danoeh.antennapod.view.EmptyViewHandler;
 import de.greenrobot.event.EventBus;
 import io.reactivex.Observable;
 import io.reactivex.android.schedulers.AndroidSchedulers;
@@ -76,7 +77,7 @@ public class AllEpisodesFragment extends Fragment {
     RecyclerView recyclerView;
     AllEpisodesRecycleAdapter listAdapter;
     private ProgressBar progLoading;
-    private View emptyView;
+    EmptyViewHandler emptyView;
 
     List<FeedItem> episodes;
     private List<Downloader> downloaderList;
@@ -334,10 +335,10 @@ public class AllEpisodesFragment extends Fragment {
             onFragmentLoaded();
         }
 
-        emptyView = root.findViewById(R.id.emptyView);
+        emptyView = new EmptyViewHandler(getContext());
-        emptyView.setVisibility(View.GONE);
+        emptyView.attachToRecyclerView(recyclerView);
-        ((TextView)emptyView.findViewById(R.id.emptyViewTitle)).setText(R.string.no_all_episodes_head_label);
+        emptyView.setTitle(R.string.no_all_episodes_head_label);
-        ((TextView)emptyView.findViewById(R.id.emptyViewMessage)).setText(R.string.no_all_episodes_label);
+        emptyView.setMessage(R.string.no_all_episodes_label);
 
         return root;
     }
@@ -350,14 +351,14 @@ public class AllEpisodesFragment extends Fragment {
                         new DefaultActionButtonCallback(mainActivity), showOnlyNewEpisodes());
                 listAdapter.setHasStableIds(true);
                 recyclerView.setAdapter(listAdapter);
+                emptyView.updateAdapter(listAdapter);
             }
-            emptyView.setVisibility(View.GONE);
             recyclerView.setVisibility(View.VISIBLE);
             listAdapter.notifyDataSetChanged();
         } else {
             listAdapter = null;
             recyclerView.setVisibility(View.GONE);
-            emptyView.setVisibility(View.VISIBLE);
+            emptyView.updateAdapter(listAdapter);
         }
 
         restoreScrollPosition();
@@ -497,7 +498,7 @@ public class AllEpisodesFragment extends Fragment {
         }
         if (viewsCreated && !itemsLoaded) {
             recyclerView.setVisibility(View.GONE);
-            emptyView.setVisibility(View.GONE);
+            emptyView.hide();
             progLoading.setVisibility(View.VISIBLE);
         }
         disposable = Observable.fromCallable(this::loadData)

app/src/main/java/de/danoeh/antennapod/fragment/FavoriteEpisodesFragment.java

@@ -51,8 +51,8 @@ public class FavoriteEpisodesFragment extends AllEpisodesFragment {
     public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         View root = super.onCreateViewHelper(inflater, container, savedInstanceState,
                 R.layout.all_episodes_fragment);
-        ((TextView)root.findViewById(R.id.emptyViewTitle)).setText(R.string.no_fav_episodes_head_label);
+        emptyView.setTitle(R.string.no_fav_episodes_head_label);
-        ((TextView)root.findViewById(R.id.emptyViewMessage)).setText(R.string.no_fav_episodes_label);
+        emptyView.setMessage(R.string.no_fav_episodes_label);
 
         ItemTouchHelper.SimpleCallback simpleItemTouchCallback = new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {
             @Override

app/src/main/java/de/danoeh/antennapod/fragment/NewEpisodesFragment.java

@@ -46,8 +46,8 @@ public class NewEpisodesFragment extends AllEpisodesFragment {
     public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         View root = super.onCreateViewHelper(inflater, container, savedInstanceState,
                 R.layout.all_episodes_fragment);
-        ((TextView)root.findViewById(R.id.emptyViewTitle)).setText(R.string.no_new_episodes_head_label);
+        emptyView.setTitle(R.string.no_new_episodes_head_label);
-        ((TextView)root.findViewById(R.id.emptyViewMessage)).setText(R.string.no_new_episodes_label);
+        emptyView.setMessage(R.string.no_new_episodes_label);
 
         ItemTouchHelper.SimpleCallback simpleItemTouchCallback = new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {
             @Override

app/src/main/java/de/danoeh/antennapod/fragment/QueueFragment.java

@@ -52,6 +52,7 @@ import de.danoeh.antennapod.core.util.LongList;
 import de.danoeh.antennapod.core.util.QueueSorter;
 import de.danoeh.antennapod.menuhandler.FeedItemMenuHandler;
 import de.danoeh.antennapod.menuhandler.MenuItemUtils;
+import de.danoeh.antennapod.view.EmptyViewHandler;
 import de.greenrobot.event.EventBus;
 import io.reactivex.Observable;
 import io.reactivex.android.schedulers.AndroidSchedulers;
@@ -72,7 +73,7 @@ public class QueueFragment extends Fragment {
     private TextView infoBar;
     private RecyclerView recyclerView;
     private QueueRecyclerAdapter recyclerAdapter;
-    private View emptyView;
+    private EmptyViewHandler emptyView;
     private ProgressBar progLoading;
 
     private List<FeedItem> queue;
@@ -502,11 +503,11 @@ public class QueueFragment extends Fragment {
             }
         );
         itemTouchHelper.attachToRecyclerView(recyclerView);
-        //empty view
+
-        emptyView = root.findViewById(R.id.emptyView);
+        emptyView = new EmptyViewHandler(getContext());
-        emptyView.setVisibility(View.GONE);
+        emptyView.attachToRecyclerView(recyclerView);
-        ((TextView)emptyView.findViewById(R.id.emptyViewTitle)).setText(R.string.no_items_header_label);
+        emptyView.setTitle(R.string.no_items_header_label);
-        ((TextView)emptyView.findViewById(R.id.emptyViewMessage)).setText(R.string.no_items_label);
+        emptyView.setMessage(R.string.no_items_label);
 
         progLoading = root.findViewById(R.id.progLoading);
         progLoading.setVisibility(View.VISIBLE);
@@ -522,13 +523,13 @@ public class QueueFragment extends Fragment {
                         new DefaultActionButtonCallback(activity), itemTouchHelper);
                 recyclerAdapter.setHasStableIds(true);
                 recyclerView.setAdapter(recyclerAdapter);
+                emptyView.updateAdapter(recyclerAdapter);
             }
-            emptyView.setVisibility(View.GONE);
             recyclerView.setVisibility(View.VISIBLE);
         } else {
             recyclerAdapter = null;
             recyclerView.setVisibility(View.GONE);
-            emptyView.setVisibility(View.VISIBLE);
+            emptyView.updateAdapter(recyclerAdapter);
         }
 
         if (restoreScrollPosition) {
@@ -641,7 +642,7 @@ public class QueueFragment extends Fragment {
         }
         if (queue == null) {
             recyclerView.setVisibility(View.GONE);
-            emptyView.setVisibility(View.GONE);
+            emptyView.hide();
             progLoading.setVisibility(View.VISIBLE);
         }
         disposable = Observable.fromCallable(DBReader::getQueue)

app/src/main/java/de/danoeh/antennapod/view/EmptyViewHandler.java

@@ -1,59 +1,95 @@
 package de.danoeh.antennapod.view;
 
-import android.app.Activity;
 import android.content.Context;
+import android.support.v7.widget.RecyclerView;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ListView;
+import android.widget.RelativeLayout;
 import android.widget.TextView;
 
 import de.danoeh.antennapod.R;
 
-public class EmptyViewHandler extends View {
+public class EmptyViewHandler {
-    private Activity activity;
+    private boolean layoutAdded = false;
-    private int title;
+    private RecyclerView recyclerView;
-    private int message;
+    private RecyclerView.Adapter adapter;
+
+    private final View emptyView;
+    private final TextView tvTitle;
+    private final TextView tvMessage;
 
     public EmptyViewHandler(Context context) {
-        super(context);
+        emptyView = View.inflate(context, R.layout.empty_view_layout, null);
-        this.setActivity((Activity) context);
+        tvTitle = emptyView.findViewById(R.id.emptyViewTitle);
-    }
+        tvMessage = emptyView.findViewById(R.id.emptyViewMessage);
-
-    public int getTitle() {
-        return title;
     }
 
     public void setTitle(int title) {
-        this.title = title;
+        tvTitle.setText(title);
-    }
-
-    public int getMessage() {
-        return message;
     }
 
     public void setMessage(int message) {
-        this.message = message;
+        tvMessage.setText(message);
     }
 
-    public void attachToListView(ListView listView){
+    public void hide() {
+        emptyView.setVisibility(View.GONE);
+    }
 
-        View  emptyView = getActivity().getLayoutInflater().inflate(R.layout.empty_view_layout, null);
+    public void attachToListView(ListView listView) {
+        if (layoutAdded) {
+            throw new IllegalStateException("Can not attach to ListView multiple times");
+        }
+        layoutAdded = true;
         ((ViewGroup) listView.getParent()).addView(emptyView);
         listView.setEmptyView(emptyView);
-
-        TextView tvTitle = (TextView) emptyView.findViewById(R.id.emptyViewTitle);
-        tvTitle.setText(title);
-
-        TextView tvMessage = (TextView) emptyView.findViewById(R.id.emptyViewMessage);
-        tvMessage.setText(message);
-
     }
 
-    public Activity getActivity() {
+    public void attachToRecyclerView(RecyclerView recyclerView) {
-        return activity;
+        if (layoutAdded) {
+            throw new IllegalStateException("Can not attach to ListView multiple times");
+        }
+        layoutAdded = true;
+        this.recyclerView = recyclerView;
+        ViewGroup parent = ((ViewGroup) recyclerView.getParent());
+        parent.addView(emptyView);
+        updateAdapter(recyclerView.getAdapter());
+
+        if (parent instanceof RelativeLayout) {
+            RelativeLayout.LayoutParams layoutParams =
+                    (RelativeLayout.LayoutParams)emptyView.getLayoutParams();
+            layoutParams.addRule(RelativeLayout.CENTER_IN_PARENT, RelativeLayout.TRUE);
+            emptyView.setLayoutParams(layoutParams);
+        }
     }
 
-    public void setActivity(Activity activity) {
+    public void updateAdapter(RecyclerView.Adapter adapter) {
-        this.activity = activity;
+        if (this.adapter != null) {
+            this.adapter.unregisterAdapterDataObserver(adapterObserver);
+        }
+        this.adapter = adapter;
+        if (adapter != null) {
+            adapter.registerAdapterDataObserver(adapterObserver);
+        }
+        updateVisibility();
+    }
+
+    private final SimpleAdapterDataObserver adapterObserver = new SimpleAdapterDataObserver() {
+        @Override
+        public void anythingChanged() {
+            updateVisibility();
+        }
+    };
+
+    private void updateVisibility() {
+        boolean empty;
+        if (adapter == null) {
+            empty = true;
+        } else {
+            empty = adapter.getItemCount() == 0;
+        }
+        recyclerView.setVisibility(empty ? View.GONE : View.VISIBLE);
+        emptyView.setVisibility(empty ? View.VISIBLE : View.GONE);
     }
 }

app/src/main/java/de/danoeh/antennapod/view/SimpleAdapterDataObserver.java

@@ -0,0 +1,41 @@
+package de.danoeh.antennapod.view;
+
+import android.support.annotation.Nullable;
+import android.support.v7.widget.RecyclerView;
+
+/**
+ * AdapterDataObserver that relays all events to the method anythingChanged().
+ */
+public abstract class SimpleAdapterDataObserver extends RecyclerView.AdapterDataObserver {
+    public abstract void anythingChanged();
+
+    @Override
+    public void onChanged() {
+        anythingChanged();
+    }
+
+    @Override
+    public void onItemRangeChanged(int positionStart, int itemCount) {
+        anythingChanged();
+    }
+
+    @Override
+    public void onItemRangeChanged(int positionStart, int itemCount, @Nullable Object payload) {
+        anythingChanged();
+    }
+
+    @Override
+    public void onItemRangeInserted(int positionStart, int itemCount) {
+        anythingChanged();
+    }
+
+    @Override
+    public void onItemRangeMoved(int fromPosition, int toPosition, int itemCount) {
+        anythingChanged();
+    }
+
+    @Override
+    public void onItemRangeRemoved(int positionStart, int itemCount) {
+        anythingChanged();
+    }
+}

app/src/main/res/layout/all_episodes_fragment.xml

@@ -17,10 +17,6 @@
         tools:itemCount="13"
         tools:listitem="@layout/new_episodes_listitem" />
 
-    <include
-        android:id="@+id/emptyView"
-        layout="@layout/empty_view_layout"/>
-
     <ProgressBar
         android:id="@+id/progLoading"
         android:layout_width="wrap_content"

app/src/main/res/layout/empty_view_layout.xml

@@ -4,6 +4,7 @@
     android:layout_height="match_parent"
     android:orientation="vertical"
     android:gravity="center"
+    android:layout_centerInParent="true"
     xmlns:tools="http://schemas.android.com/tools">
 
     <TextView

app/src/main/res/layout/queue_fragment.xml

@@ -27,10 +27,6 @@
         android:layout_below="@id/divider"
         android:scrollbars="vertical"/>
 
-    <include
-        android:id="@+id/emptyView"
-        layout="@layout/empty_view_layout"/>
-
     <ProgressBar
         android:id="@+id/progLoading"
         android:layout_width="wrap_content"