Using startForeground() with an Intent Service

Question

I am trying to keep alive a service that reacts to screen on/off changes. The service would work perfectly for awhile, but then eventually it would be killed. I am now attem

Answer 1

IntentService automatically shuts down when onHandleIntent() completes. It is to perform a brief bit of work when something occurs. It is not supposed to live for more than a few seconds, typically.

I am going to assume that this is tied to what I wrote in your last question in this area.

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Something in the rest of your app will be registering and unregistering the BroadcastReceiver for the screen on/off events -- apparently, from your comments, it is an activity. If what you want to do when those things occur is very very quick (on the order of a few milliseconds), just do the work in onReceive(), and be done with it.

If, on the other hand, you have more work than a few milliseconds' worth, you will need to have that work be done by something else that can do the work on a background thread. For example, if the "something in the rest of your app" that registered the BroadcastReceiver is indeed an activity, the activity might just spawn an AsyncTask to do the work.

Another possibility is to use an IntentService. You elected to go down this path in your work prior to that last question. I do not know why. Regardless, an IntentService, like an AsyncTask, is supposed to be a short-lived component -- you send it a command via startService(), it does its work in onHandleIntent(), and it goes away.

With all that in mind, let's talk about your specific points.

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The service would work perfectly for awhile, but then eventually it would be killed.

It is unclear what you think "killed" means. An IntentService automatically goes away once onHandleIntent() returns, and that ideally should occur within a handful of seconds.

I am now attempting to use startForeground() to keep the process alive, but it still seems to be dying.

Again, it is unclear what you think "dying" means. Bear in mind that the mere existence of an IntentService does not stop the CPU from shutting down once the screen turns off, and startForeground() has nothing to do with that.

Also, as a side note, Logcat complains about a leak, as unregisterReceiver() is not called (except manually by a button press from the user)..

You also need to unregister the receiver before the user exits the activity. It is usually a good idea to call registerReceiver() in onResume() and unregisterReceiver() in onPause().