How long can a notification be kept for (permanently)?

Issue

I have a service with startForeground(requestCode, notification); and have it set so that setOngoing(true) so the user cannot remove notification. How long does this notification stay alive for? Will it stay alive forever (until user restarts phone)?

I have noticed that if I start the service and let the phone sit idle for a few hours that the notification is still present but becomes unresponsive to the button click service methods. Is this the case because I do not have a partial wake lock?

This notification is for controlling android settings like brightness setting which is why I need the notification running always.

Would it be better to use a normal notification with setOngoing(true) and then start a service which would call a method for each button that is clicked?

Solution

The solution that seems to keep the service/notification running is to use a repeating alarm:

public void startAlarm(){
    alarmMgr = (AlarmManager)this.getSystemService(Context.ALARM_SERVICE);
    Intent intent = new Intent(this, NotificationService.class);
    alarmIntent = PendingIntent.getService(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
    alarmMgr.setRepeating(AlarmManager.ELAPSED_REALTIME, SystemClock.elapsedRealtime(), 200*1000, alarmIntent);
}

I am not certain of the optimum frequency for resetting the alarm, but I have set it to a few minutes for now. Every few minutes my service is started/resumed.

Answered By - JunaidS