title: The same push notification keeps appearing whenever i open my apps
body: <p>The same push notification keeps appearing whenever I reopen my apps although i have already cleared the notification in the notification bar. Secondly how do I implement a service so that my apps can receive notification although the apps is closed.</p>
  
  <pre><code> @Override
  public IBinder onBind(Intent intent) {
  return null;
  }
  
  
  @Override
  
  public int onStartCommand(Intent intent, int flags, int startId) {
  
  SharedPreferences sharedPreferences = getSharedPreferences(Constants.SHARED_PREF, MODE_PRIVATE);
  
  
  String id = sharedPreferences.getString(Constants.UNIQUE_ID, null);
  
  
  Firebase firebase = new Firebase(Constants.FIREBASE_APP + id);
  
  
  
  firebase.addValueEventListener(new ValueEventListener() {
  
  
      @Override
      public void onDataChange(DataSnapshot snapshot) {
  
          String msg = snapshot.child("msg").getValue().toString();
  
  
          if (msg.equals("none"))
              return;
  
          showNotification(msg);
      }
  
      @Override
      public void onCancelled(FirebaseError firebaseError) {
          Log.e("The read failed: ", firebaseError.getMessage());
      }
  });
  
  return START_STICKY;
   }
  
  
  private void showNotification(String msg){
  NotificationCompat.Builder builder = new NotificationCompat.Builder(this);
  builder.setSmallIcon(R.mipmap.ic_launcher);
  Intent intent = new Intent(NotificationListener.this,ViewRecord.class);
  PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, 0);
  builder.setContentIntent(pendingIntent);
  Uri alarmSound = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
  builder.setSound(alarmSound);
  builder.setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher));
  builder.setContentTitle("Notifier");
  builder.setContentText(msg);
  NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
  builder.setAutoCancel(true);
  notificationManager.notify(1, builder.build());
  }
  </code></pre>
  
  <p>my service code as below. and i call the service at onCreate function in the 1st activity..</p>
  
  <pre><code>public class MyService extends Service {
  public MyService() {
  }
  
  @Override
  public IBinder onBind(Intent intent) {
      // TODO: Return the communication channel to the service.
      throw new UnsupportedOperationException("Not yet implemented");
  }
  
  @Override
  public void onCreate() {
      Toast.makeText(this, "The new Service was Created", Toast.LENGTH_LONG).show();
  
  }
  
  @Override
  public void onStart(Intent intent, int startId) {
      // For time consuming an long tasks you can launch a new thread here...
      Toast.makeText(this, " Service Started", Toast.LENGTH_LONG).show();
  
  }
   }
  </code></pre>