Prevent concurrent queue modifications from breaking the cast demo app UI

PiperOrigin-RevId: 233577854

demos/cast/src/main/java/com/google/android/exoplayer2/castdemo/MainActivity.java

@@ -211,6 +211,7 @@ public class MainActivity extends AppCompatActivity
   private class QueueItemViewHolder extends RecyclerView.ViewHolder implements OnClickListener {
 
     public final TextView textView;
+    public MediaItem item;
 
     public QueueItemViewHolder(TextView textView) {
       super(textView);
@@ -236,8 +237,9 @@ public class MainActivity extends AppCompatActivity
 
     @Override
     public void onBindViewHolder(QueueItemViewHolder holder, int position) {
+      holder.item = playerManager.getItem(position);
       TextView view = holder.textView;
-      view.setText(playerManager.getItem(position).title);
+      view.setText(holder.item.title);
       // TODO: Solve coloring using the theme's ColorStateList.
       view.setTextColor(ColorUtils.setAlphaComponent(view.getCurrentTextColor(),
            position == playerManager.getCurrentItemIndex() ? 255 : 100));
@@ -278,7 +280,8 @@ public class MainActivity extends AppCompatActivity
     @Override
     public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
       int position = viewHolder.getAdapterPosition();
-      if (playerManager.removeItem(position)) {
+      QueueItemViewHolder queueItemHolder = (QueueItemViewHolder) viewHolder;
+      if (playerManager.removeItem(queueItemHolder.item)) {
         mediaQueueListAdapter.notifyItemRemoved(position);
         // Update whichever item took its place, in case it became the new selected item.
         mediaQueueListAdapter.notifyItemChanged(position);
@@ -289,8 +292,9 @@ public class MainActivity extends AppCompatActivity
     public void clearView(RecyclerView recyclerView, ViewHolder viewHolder) {
       super.clearView(recyclerView, viewHolder);
       if (draggingFromPosition != C.INDEX_UNSET) {
+        QueueItemViewHolder queueItemHolder = (QueueItemViewHolder) viewHolder;
         // A drag has ended. We reflect the media queue change in the player.
-        if (!playerManager.moveItem(draggingFromPosition, draggingToPosition)) {
+        if (!playerManager.moveItem(queueItemHolder.item, draggingToPosition)) {
           // The move failed. The entire sequence of onMove calls since the drag started needs to be
           // invalidated.
           mediaQueueListAdapter.notifyDataSetChanged();

demos/cast/src/main/java/com/google/android/exoplayer2/castdemo/PlayerManager.java

@@ -168,10 +168,16 @@ import java.util.ArrayList;
   /**
    * Removes the item at the given index from the media queue.
    *
-   * @param itemIndex The index of the item to remove.
+   * @param item The item to remove.
    * @return Whether the removal was successful.
    */
-  public boolean removeItem(int itemIndex) {
+  public boolean removeItem(MediaItem item) {
+    int itemIndex = mediaQueue.indexOf(item);
+    if (itemIndex == -1) {
+      // This may happen if another sender app removes items while this sender app is in "swiping
+      // an item" state.
+      return false;
+    }
     concatenatingMediaSource.removeMediaSource(itemIndex);
     mediaQueue.remove(itemIndex);
     if (currentPlayer == exoCastPlayer) {
@@ -188,20 +194,29 @@ import java.util.ArrayList;
   /**
    * Moves an item within the queue.
    *
-   * @param fromIndex The index of the item to move.
-   * @param toIndex The target index of the item in the queue.
-   * @return Whether the item move was successful.
+   * @param item The item to move. This method does nothing if {@code item} is not contained in the
+   *     queue.
+   * @param toIndex The target index of the item in the queue. If {@code toIndex} exceeds the last
+   *     position in the queue, {@code toIndex} is clamped to match the largest possible value.
+   * @return True if {@code item} was contained in the queue, and {@code toIndex} was a valid
+   *     position. False otherwise.
    */
-  public boolean moveItem(int fromIndex, int toIndex) {
-    mediaQueue.add(toIndex, mediaQueue.remove(fromIndex));
-    concatenatingMediaSource.moveMediaSource(fromIndex, toIndex);
+  public boolean moveItem(MediaItem item, int toIndex) {
+    int indexOfItem = mediaQueue.indexOf(item);
+    if (indexOfItem == -1) {
+      // This may happen if another sender app removes items while this sender app is in "dragging
+      // an item" state.
+      return false;
+    }
+    int clampedToIndex = Math.min(toIndex, mediaQueue.size() - 1);
+    mediaQueue.add(clampedToIndex, mediaQueue.remove(indexOfItem));
+    concatenatingMediaSource.moveMediaSource(indexOfItem, clampedToIndex);
     if (currentPlayer == exoCastPlayer) {
-      exoCastPlayer.moveItemInQueue(fromIndex, toIndex);
+      exoCastPlayer.moveItemInQueue(indexOfItem, clampedToIndex);
     }
-
     // Index update.
     maybeSetCurrentItemAndNotify(currentPlayer.getCurrentWindowIndex());
-    return true;
+    return clampedToIndex == toIndex;
   }
 
   // Miscellaneous methods.