Question

i want when a new message received by onMessage() inside GCMIntentService.java , the onMessage() call a method called blinkLED() inside the MainActivity.java so the blinkLED() method can use the data received by onMessage() , how can i implement that ? a sample code will be helpful.

Answer 1

Use BroadcastReceiver. This tutorial shows you how to send a broadcast intent from a class, and have another class handles it.

Short example, in your GCMIntentService::onMessage(), you may have this:

Intent intent = new Intent();
intent.setAction("com.my.app.blinkled");
sendBroadcast(intent); 

Then in your MainActivity, you implements a BroadcastReceiver :

private class MyBroadcastReceiver extends BroadcastReceiver {
  @Override
  public void onReceive(Context context, Intent intent) {
    blinkLED();
  }
} 

and register for it in onResume() of MainActivity:

IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction("com.my.app.blinkled");
receiver = new MyBroadcastReceiver();
registerReceiver(receiver, intentFilter);