@Override
 public boolean onOptionsItemSelected(MenuItem item) {
   if (btService != null) {
     btService.stopSelf();
     btService = null;
   }
   finish();
   return super.onOptionsItemSelected(item);
 }
 @Override
 protected void onDestroy() {
   if (btService != null) {
     btService.unregisterChannel(CHANNEL_ID);
   }
   if (btService != null && shouldStop) {
     btService.stopSelf();
   }
   unbindService(connection);
   super.onDestroy();
 }