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Android Threads and Services But Wait There's More! Messengers and Handlers: Activity

Patrick Coyne
Patrick Coyne
5,026 Points
Posted by Patrick Coyne
Patrick Coyne
5,026 Points

ReplyTo from Service to activity

I am not sure which part is going wrong and the only thing it returns is Bummer Try again so any feedback would be helpful. Here is the question

"Handle the Message in GeolocationService, and use the 'replyTo' property to send a new Message back to MainActivity with the latitude in 'arg1' and the longitude in 'arg2'. Then call setCoordinates(int lat, int long) from within MainActivity to update the coordinates."

MainActivity.java 
// some methods omitted
public class MainActivity extends Activity {
    Boolean isBound = false;
    Messenger mServiceMessenger;
  Messenger activityMessenger = new Messenger(new ActivityHandler());

    ServiceConnection mServiceConnection = new ServiceConnection() {
      @Override  
      public void onServiceConnected(ComponentName name, IBinder binder) {
        isBound = true;
        mServiceMessenger = new Messenger(binder);
        Message message = Message.obtain();
            message.replyTo = activityMessenger;
                mServiceMessenger.send(message);

      }

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

  public void setCoordinates(int lat, int lon){
  }

  public class ActivityHandler extends Handler{

        @Override
    public void handleMessage(Message msg) {
      setCoordinates(msg.arg1, msg.arg2);
    }
  }
}
GeolocationService.java 
// 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;
        message.replyTo = mMessenger;
        message.replyTo.send(message);
      }
    }
}
Difficulty.java 
  public class Difficulty {
    public static Boolean HARDMODE = false;    
  }

1 Answer

Matthew Timmons
Matthew Timmons
33,804 Points
Matthew Timmons
Matthew Timmons
33,804 Points

Hi. I think your method for setCoordinates() is overriding the class' method of the same name. I think the challenge assumes there is already a setCoordinates() method.

I would also recommend double-checking the contents of your LocationHandler's handleMessage() function:

public void handleMessage(Message msg) { mLatitude = getLatitude(); mLongitude = getLongitude(); Message message = Message.obtain(); message.arg1 = mLatitude; message.arg2 = mLongitude; message.replyTo = mMessenger; message.replyTo.send(message); }

Let me know if you have any questions or want a hint. Thanks!