Add method to query whether a command is available

- Other commands will be added later.
- The returned value is a boolean until we decide what it should be.

PiperOrigin-RevId: 357535877

library/common/src/main/java/com/google/android/exoplayer2/BasePlayer.java

@@ -71,6 +71,14 @@ public abstract class BasePlayer implements Player {
     removeMediaItems(/* fromIndex= */ index, /* toIndex= */ index + 1);
   }
 
+  @Override
+  public boolean isCommandAvailable(@Command int command) {
+    if (command == COMMAND_SEEK_TO_NEXT_MEDIA_ITEM) {
+      return hasNext();
+    }
+    throw new IllegalArgumentException();
+  }
+
   @Override
   public final void play() {
     setPlayWhenReady(true);

library/common/src/main/java/com/google/android/exoplayer2/Player.java

@@ -929,6 +929,17 @@ public interface Player {
   /** {@link #getPlaybackParameters()} changed. */
   int EVENT_PLAYBACK_PARAMETERS_CHANGED = 13;
 
+  /**
+   * Commands that can be executed on a {@code Player}. One of {@link
+   * #COMMAND_SEEK_TO_NEXT_MEDIA_ITEM}.
+   */
+  @Documented
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({COMMAND_SEEK_TO_NEXT_MEDIA_ITEM})
+  @interface Command {}
+  /** Command to seek to the next {@link MediaItem} in the playlist. */
+  int COMMAND_SEEK_TO_NEXT_MEDIA_ITEM = 0;
+
   /** Returns the component of this player for audio output, or null if audio is not supported. */
   @Nullable
   AudioComponent getAudioComponent();
@@ -1100,6 +1111,19 @@ public interface Player {
   /** Clears the playlist. */
   void clearMediaItems();
 
+  /**
+   * Returns whether the provided {@link Command} is available.
+   *
+   * <p>This method does not execute the command.
+   *
+   * <p>Executing a command that is not available (for example, calling {@link #next()} if {@link
+   * #COMMAND_SEEK_TO_NEXT_MEDIA_ITEM} is unavailable) is a no-op.
+   *
+   * @param command A {@link Command}.
+   * @return Whether the {@link Command} is available.
+   */
+  boolean isCommandAvailable(@Command int command);
+
   /** Prepares the player. */
   void prepare();
 

library/ui/src/main/java/com/google/android/exoplayer2/ui/PlayerControlView.java

@@ -916,7 +916,8 @@ public class PlayerControlView extends FrameLayout {
         enablePrevious = isSeekable || !window.isDynamic || player.hasPrevious();
         enableRewind = isSeekable && controlDispatcher.isRewindEnabled();
         enableFastForward = isSeekable && controlDispatcher.isFastForwardEnabled();
-        enableNext = window.isLive() || player.hasNext();
+        enableNext =
+            window.isLive() || player.isCommandAvailable(Player.COMMAND_SEEK_TO_NEXT_MEDIA_ITEM);
       }
     }
 

library/ui/src/main/java/com/google/android/exoplayer2/ui/StyledPlayerControlView.java

@@ -1144,7 +1144,8 @@ public class StyledPlayerControlView extends FrameLayout {
         enablePrevious = isSeekable || !window.isDynamic || player.hasPrevious();
         enableRewind = isSeekable && controlDispatcher.isRewindEnabled();
         enableFastForward = isSeekable && controlDispatcher.isFastForwardEnabled();
-        enableNext = window.isLive() || player.hasNext();
+        enableNext =
+            window.isLive() || player.isCommandAvailable(Player.COMMAND_SEEK_TO_NEXT_MEDIA_ITEM);
       }
     }