Task 4 problem

// some methods omitted
public class MainActivity extends Activity {
    Boolean isBound = false;
    int latitude;
    int longitude;

    Messenger mServiceMessenger;
      Messenger mActivityMessenger = new Messenger(new ActivityHandler());



    ServiceConnection mServiceConnection = new ServiceConnection() {
      @Override  
      public void onServiceConnected(ComponentName name, IBinder binder) {
        isBound = true;
        mServiceMessenger = new Messenger(binder);
                  if (mServiceMessenger != null) {

                    Message msg = Message.obtain();
                    msg.replyTo = mActivityMessenger;
                    mServiceMessenger.send(msg);
                  }

      }

      @Override
      public void onServiceDisconnected(ComponentName name) {
        isBound = false;
      }
    };

    public void setCoordinates(int lat, int longi) {
      latitude = lat;
      longitude = longi;
    }


  class ActivityHandler extends Handler {
       MainActivity mMainActivity;



    @Override
    public void handleMessage(Message msg) {
              setCoordinates(msg.arg1, msg.arg2);

    }

  }
}

// some methods omitted
public class GeolocationService extends Service {
    int mLatitude;
    int mLongitude;
    Messenger mMessenger = new Messenger(new LocationHandler());

    @Override
    public IBinder onBind(Intent intent) {
      return mMessenger.getBinder();
    }

   class LocationHandler extends Handler {
      @Override
      public void handleMessage(Message msg) {

        mLatitude = getLatitude();
        mLongitude = getLongitude();

        Message message = Message.obtain();
        message.arg1 = mLatitude; 
        message.arg2 = mLongitude;

        msg.replyTo = mMessenger;
        msg.replyTo.send(message);


      }
    }
}

  public class Difficulty {
    public static Boolean HARDMODE = false;    
  }