public void removeObserver() {
   NotificationManager.getInstance().removeObserver(this, NotificationManager.audioDidReset);
   NotificationManager.getInstance()
       .removeObserver(this, NotificationManager.audioPlayStateChanged);
   NotificationManager.getInstance().removeObserver(this, NotificationManager.audioDidStarted);
   NotificationManager.getInstance()
       .removeObserver(this, NotificationManager.audioProgressDidChanged);
   NotificationManager.getInstance().removeObserver(this, NotificationManager.newaudioloaded);
 }
 public void addObserver() {
   TAG_Observer = MediaController.getInstance().generateObserverTag();
   NotificationManager.getInstance().addObserver(this, NotificationManager.audioDidReset);
   NotificationManager.getInstance().addObserver(this, NotificationManager.audioPlayStateChanged);
   NotificationManager.getInstance().addObserver(this, NotificationManager.audioDidStarted);
   NotificationManager.getInstance()
       .addObserver(this, NotificationManager.audioProgressDidChanged);
   NotificationManager.getInstance().addObserver(this, NotificationManager.newaudioloaded);
 }