title: Generate int unique id as android notification id
body: <p>When I send multiple push notifications, I need them to be all shown in the notification bar ordered by the time sent desc. I know I should use unique notification - I tried to generate random number but that did not solve my problem since I need them to be ordered. I tried to use <code>AtomicInt</code> and still don't have the desired result.</p>
  
  <pre><code>package com.mypackage.lebadagency;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import android.app.IntentService;
  import android.app.Notification;
  import android.app.NotificationManager;
  import android.app.PendingIntent;
  import android.content.Context;
  import android.content.Intent;
  import android.graphics.Color;
  import android.os.Bundle;
  import android.os.SystemClock;
  import android.support.v4.app.NotificationCompat;
  import android.util.Log;
  
  
  
  import android.widget.RemoteViews;
  
  import com.google.android.gms.gcm.GoogleCloudMessaging;
  
  public class GCMNotificationIntentService extends IntentService {
  
    private AtomicInteger c = new AtomicInteger(0);
    public int NOTIFICATION_ID = c.incrementAndGet(); 
  
    private NotificationManager mNotificationManager;
    NotificationCompat.Builder builder;
  
    public GCMNotificationIntentService() {
      super("GcmIntentService");
    }
  
    public static final String TAG = "GCMNotificationIntentService";
  
    @Override
    protected void onHandleIntent(Intent intent) {
      Bundle extras = intent.getExtras();
      GoogleCloudMessaging gcm = GoogleCloudMessaging.getInstance(this);
  
      String messageType = gcm.getMessageType(intent);
  
      if (!extras.isEmpty()) {
        if (GoogleCloudMessaging.MESSAGE_TYPE_SEND_ERROR
            .equals(messageType)) {
          sendNotification("Send error: " + extras.toString());
        } else if (GoogleCloudMessaging.MESSAGE_TYPE_DELETED
            .equals(messageType)) {
          sendNotification("Deleted messages on server: "
              + extras.toString());
        } else if (GoogleCloudMessaging.MESSAGE_TYPE_MESSAGE
            .equals(messageType)) {
  
          for (int i = 0; i &lt; 3; i++) {
            Log.i(TAG,
                "Working... " + (i + 1) + "/5 @ "
                    + SystemClock.elapsedRealtime());
            try {
              Thread.sleep(5000);
            } catch (InterruptedException e) {
            }
  
          }
          Log.i(TAG, "Completed work @ " + SystemClock.elapsedRealtime());
  
          sendNotification(""
              + extras.get(Config.MESSAGE_KEY));
          Log.i(TAG, "Received: " + extras.toString());
        }
      }
      GcmBroadcastReceiver.completeWakefulIntent(intent);
    }
  
    private void sendNotification(String msg) {
  
      Log.d(TAG, "Preparing to send notification...: " + msg);
      mNotificationManager = (NotificationManager) this
          .getSystemService(Context.NOTIFICATION_SERVICE);
      //here start
      Intent gcmintent = new Intent(this, AppGcmStation.class);
      gcmintent.putExtra("ntitle", msg);
      gcmintent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
      int requestID = (int) System.currentTimeMillis();
      //here end
      PendingIntent contentIntent = PendingIntent.getActivity(this, requestID,
          gcmintent, PendingIntent.FLAG_UPDATE_CURRENT);
  
      NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(
          this).setSmallIcon(R.drawable.ic_launcher)
          .setContentTitle("my title")
          .setStyle(new NotificationCompat.BigTextStyle().bigText(msg))
          .setContentText(msg);
      mBuilder.setAutoCancel(true);
      mBuilder.setTicker(msg);
      mBuilder.setVibrate(new long[] { 1000, 1000, 1000, 1000, 1000 }); 
      mBuilder.setLights(Color.RED, 3000, 3000);
      mBuilder.setContentIntent(contentIntent);
      mBuilder.setDefaults(Notification.DEFAULT_SOUND);
  
  
  
      mNotificationManager.notify(NOTIFICATION_ID, mBuilder.build());
      Log.d(TAG, "Notification sent successfully.");
    }
  }
  </code></pre>
  
  <p>I need the BEST and simplest way to generate an int id which is incremental to assign it as the notification id.</p>