Simplify empty view handling on recycler views

2 files changed, 105 insertions, 28 deletions

diff --git a/app/src/main/java/de/danoeh/antennapod/view/EmptyViewHandler.java b/app/src/main/java/de/danoeh/antennapod/view/EmptyViewHandler.java
index e3fd63235..42c11bc8e 100644
--- a/app/src/main/java/de/danoeh/antennapod/view/EmptyViewHandler.java
+++ b/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 {

-    private Activity activity;

-    private int title;

-    private int message;

+public class EmptyViewHandler {

+    private boolean layoutAdded = false;

+    private RecyclerView recyclerView;

+    private RecyclerView.Adapter adapter;

 

-    public EmptyViewHandler(Context context) {

-        super(context);

-        this.setActivity((Activity) context);

-    }

+    private final View emptyView;

+    private final TextView tvTitle;

+    private final TextView tvMessage;

 

-    public int getTitle() {

-        return title;

+    public EmptyViewHandler(Context context) {

+        emptyView = View.inflate(context, R.layout.empty_view_layout, null);

+        tvTitle = emptyView.findViewById(R.id.emptyViewTitle);

+        tvMessage = emptyView.findViewById(R.id.emptyViewMessage);

     }

 

     public void setTitle(int title) {

-        this.title = title;

-    }

-

-    public int getMessage() {

-        return message;

+        tvTitle.setText(title);

     }

 

     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 void attachToRecyclerView(RecyclerView recyclerView) {

+        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 Activity getActivity() {

-        return activity;

+    public void updateAdapter(RecyclerView.Adapter adapter) {

+        if (this.adapter != null) {

+            this.adapter.unregisterAdapterDataObserver(adapterObserver);

+        }

+        this.adapter = adapter;

+        if (adapter != null) {

+            adapter.registerAdapterDataObserver(adapterObserver);

+        }

+        updateVisibility();

     }

 

-    public void setActivity(Activity activity) {

-        this.activity = activity;

+    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);

     }

 }

diff --git a/app/src/main/java/de/danoeh/antennapod/view/SimpleAdapterDataObserver.java b/app/src/main/java/de/danoeh/antennapod/view/SimpleAdapterDataObserver.java
new file mode 100644
index 000000000..45c3a35bd
--- /dev/null
+++ b/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();
+    }
+}