android - Schedule notification not triggered

Question

I have an application that i want it to launch a notification every x days(predefined by user). For that I'm using this code: Class extends broadcast receiver:

public class OnAlarmReceiver extends BroadcastReceiver{
    @Override
     public void onReceive(Context context, Intent intent) {


        String ns = Context.NOTIFICATION_SERVICE;
        NotificationManager mNotificationManager = (NotificationManager) context.getSystemService(ns);

        int icon = R.drawable.icon;
        CharSequence tickerText = "Votre vidange approche";
        long when = System.currentTimeMillis();

        Notification notification = new Notification(icon, tickerText, when);


        CharSequence contentTitle = "Notification";
        CharSequence contentText = "Vérifier votre kilométrage";
        Intent notificationIntent = new Intent(context, Acceuil.class);
        PendingIntent contentIntent = PendingIntent.getActivity(context, 0, notificationIntent, 0);

        notification.setLatestEventInfo(context, contentTitle, contentText, contentIntent);

        final int HELLO_ID = 1;

        mNotificationManager.notify(HELLO_ID, notification);
     }

    }

And this function in the other class to launch this previous class:

public void repeating() {
        AlarmManager mgr=(AlarmManager)context.getSystemService(Context.ALARM_SERVICE);
        Intent i=new Intent(context, OnAlarmReceiver.class);
        PendingIntent pi=PendingIntent.getBroadcast(context, 0, i, 0);
        mgr.setRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP, SystemClock.elapsedRealtime(), 1800000, pi);

    }

I set it to launch every half hour the notification but i never had it. What's going on with this code?

Thank you very much.

Answer 1

SystemClock.elapsedRealtime() means 'now' up to the millisecond, so there is a possibility that by the time it gets a chance to run, the triggerAtTime will have passed (not sure how AlarmManager handles this case). Try delaying it a few seconds to see if it runs properly: SystemClock.elapsedRealtime() + 10 * 1000.

On another note, repeating alarms with large intervals (such as days) are unreliable: if you process is killed, or throws an exception, or the device is rebooted, then it's alarms will be cleared. One alternative (although not 100% bulletproof) would be to schedule each next alarm from the previous one and save the time it will run to shared preferences for example. Then each time your application starts, check if the next run time is valid (i.e., in the future), and if not schedule a new alarm.