public void onStart() {
   super.onStart();
   if (App42GCMController.isPlayServiceAvailable(this)) {
     App42GCMController.getRegistrationId(MainActivity.this, GoogleProjectNo);
   } else {
     Log.i("App42PushNotification", "No valid Google Play Services APK found.");
   }
 }
 /**
  * @param context
  * @param googleProjectNo
  * @param callBack
  */
 @SuppressLint("NewApi")
 public static void getRegistrationId(
     Context context, String googleProjectNo, App42GCMListener callBack) {
   GoogleCloudMessaging gcm = GoogleCloudMessaging.getInstance(context);
   String regid = App42GCMController.getRegistrationId(context);
   if (regid.isEmpty()) {
     registeronGCM(context, googleProjectNo, gcm, callBack);
   } else callBack.onGCMRegistrationId(regid);
 }