MediaPlayerHolder.java

private void initializeMediaPlayer() {
   if (mMediaPlayer == null) {
       mMediaPlayer = new MediaPlayer();
       mMediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
           @Override
           public void onCompletion(MediaPlayer mediaPlayer) {
               stopUpdatingCallbackWithPosition(true);
               logToUI("MediaPlayer playback completed");
               if (mPlaybackInfoListener != null) {
                   mPlaybackInfoListener.onStateChanged(PlaybackInfoListener.State.COMPLETED);
                   mPlaybackInfoListener.onPlaybackCompleted();
               }
           }
       });
   }
}

@Override
public void play() {
   if (mMediaPlayer != null && !mMediaPlayer.isPlaying()) {
       logToUI(String.format("playbackStart() %s",
                             mContext.getResources().getResourceEntryName(mResourceId)));
       mMediaPlayer.start();
       if (mPlaybackInfoListener != null) {
           mPlaybackInfoListener.onStateChanged(PlaybackInfoListener.State.PLAYING);
       }
       startUpdatingCallbackWithPosition();
   }
}

@Override
public void pause() {
   if (mMediaPlayer != null && mMediaPlayer.isPlaying()) {
       mMediaPlayer.pause();
       if (mPlaybackInfoListener != null) {
           mPlaybackInfoListener.onStateChanged(PlaybackInfoListener.State.PAUSED);
       }
   }
}

@Override
public void reset() {
   if (mMediaPlayer != null) {
       logToUI("playbackReset()");
       mMediaPlayer.reset();
       loadMedia(mResourceId);
       if (mPlaybackInfoListener != null) {
           mPlaybackInfoListener.onStateChanged(PlaybackInfoListener.State.RESET);
       }
       stopUpdatingCallbackWithPosition(true);
   }
}

@Override
public void loadMedia(int resourceId) {
   mResourceId = resourceId;

   initializeMediaPlayer();

   AssetFileDescriptor assetFileDescriptor =
           mContext.getResources().openRawResourceFd(mResourceId);
   try {
       mMediaPlayer.setDataSource(assetFileDescriptor);
   } catch (Exception e) {
       logToUI(e.toString());
   }

   try {
       mMediaPlayer.prepare();
   } catch (Exception e) {
       logToUI(e.toString());
   }

   initializeProgressCallback();
}