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I have an application that does something in a service triggered by an alarm every 10 minutes while the app is in the background. I want the Alarm to keep going off even if the OS kills the app (So its dead and have to relaunch) and only kill it if the user actually removes the app from recent apps or force kills it from settings (or is logged off but that already works). I have tried many different approaches, latest I tried this http://www.dotkam.com/2011/01/10/android-prefer-alarms-and-intent-receivers-to-services/ without any luck. My Alarm looks like this. 

    if(ActivityLifecycleHandler.isApplicationInForeground()) {
        return;   // If App is in foreground do not start alarm!
    }

    String alarm = Context.ALARM_SERVICE;
    AlarmManager am = ( AlarmManager ) context.getSystemService( alarm );

    Intent intent = new Intent(locationBroadcastAction);
    PendingIntent pi = PendingIntent.getBroadcast( context.getApplicationContext(), 0, intent, 0 );

    int type = AlarmManager.ELAPSED_REALTIME_WAKEUP;

    // Set trigger time to 0, because want to fire off the first one instantly
    am.setRepeating( type, 0, ONE_MINUTE, pi );

And the BroadcastReceiver:

public class LocationBroadcastReceiver extends BroadcastReceiver{

@Override
public void onReceive(Context context, Intent intent ) {

    Intent myIntent = new Intent( context, LocationService.class );
    context.startService( myIntent );
}
}

Any idea of what I am doing wrong? Everything works fine until the OS kills the app.

Slagathor
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1 Answers1

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The alarm should goes off if the app was killed, even if if was removed from the recent app (but not if it was force-stopped).

It is actually the whole point of using the AlarmManager :

Note: The Alarm Manager is intended for cases where you want to have your application code run at a specific time, even if your application is not currently running. For normal timing operations (ticks, timeouts, etc) it is easier and much more efficient to use Handler.

You can see if the alarm is still there with :

adb shell dumpsys alarm

What is probably happening is that the device is woken up to receive the alarm, but fall asleep again as soon as the receiver finishes, before the service can start.

The receiver should take a wake lock (to be released by the service). The support library provides a WakefulBroadcastReceiver which does exactly that :

Helper for the common pattern of implementing a BroadcastReceiver that receives a device wakeup event and then passes the work off to a Service, while ensuring that the device does not go back to sleep during the transition.

bwt
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  • Aaah, great! Yeah I actually thought that was the whole point of the Alarm too, but I just could not get it to work properly so I had doubts. I will try this out and check if it works. Thanks anyway for the information. Btw, will the user notice that the service is running for about 5 seconds in any way since its wakeful? – Slagathor Aug 09 '16 at 09:35
  • Ah, the Alarm is actually not showing the in the dump after the app dies.. – Slagathor Aug 09 '16 at 13:49
  • That's strange, I tried your code on API 21 and it seems to work. even if the app has been killed and the screen is off : the process is created, and the receiver gets the alarm. The only thing that may be different is that the Receiver is statically registered (otherwise the system does not know how to recreate it), but it doesn't explain why the alarm disappear from the list. – bwt Aug 09 '16 at 16:42
  • Thanks for your help. I actually think I figured out why it did not work. It was due to some special battery settings in Huawei devices. Found this StackOverflow question explaining it. Testing it out now. http://stackoverflow.com/questions/34729966/alarmmanager-not-working-in-several-devices – Slagathor Aug 09 '16 at 18:06