Service not starting on Oreo in app widget using PendingIntent

You can no longer start a service in background in 8.0, but you can use JobScheduler to achieve similar results. There is also a JobIntentService helper class that allows you to switch to JobScheduler from service without much refatoring. And you cannot use PendingIntent pointing to a service, but you can use one pointing to an Activity or BroadcastReceiver.

If you had a working widget pre 8.0, and now you need to make it work on android 8.0, just perform this simple steps:

1. Change your IntentService class to JobIntentService
2. Rename service onHandleIntent method to onHandleWork (same parameters)
3. Add BIND_JOB_SERVICE permission to your service in the manifest:

    <service android:name=".widget.MyWidgetService"
           android:permission="android.permission.BIND_JOB_SERVICE">
    </service>

4. To start this service, you must no longer use context.startService. Instead use enqueueWork static method (where JOB_ID is just an unique integer constant, must be the same value for all work enqueued for the same class):

    enqueueWork(context, MyWidgetService.class, JOB_ID, intent);

5. For clicks, replace your pendingIntent that was pointing to service with a pendingIntent that points to a BroadcastReceiver. Since your subclass of AppWidgetProvider is a BroadcastReceiver itself, you might as well use it:

    Intent myIntent = new Intent(context, MyAppWidgetProvider.class);
    myIntent .setAction("SOME_UNIQUE_ACTION");
    pendingIntent = PendingIntent.getBroadcast(context, 0, myIntent, PendingIntent.FLAG_UPDATE_CURRENT);

6. In onReceive start the service using enqueueWork (If your PendingIntent was starting the activity, just leave it be - it'll work just fine on android 8.0+):

    @Override
    public void onReceive(Context context, Intent intent) {
        super.onReceive(context, intent);
        if (intent.getAction().equals("SOME_UNIQUE_ACTION")) {
            MyWidgetService.enqueueWork(.....);
        }
    }

7. To ensure that the widget will work on old devices, make sure you have WAKE_LOCK permission in your manifest (used by JobIntentService on old devices).

That's it. This widget will now work properly on both new and old devices. The only real difference will be that if your 8.0 device is in doze mode it may not update widget all that often, but that shouldn't be a problem because if it is dozing, that means that user can't see your widget right now anyways.

Could goasyc be an option? You could change your PendingIntent to fire a BroadcastReceiver, then in the OnRecieve method, you can call goasync() Then you should be able to use the PendingResult it generates to create an async call. Still don't think you can start a service.

How to use "goAsync" for broadcastReceiver?

As you note, an app widget does not count for the PendingIntent background whitelist. I do not know why — it would seem to be about on par with a PendingIntent started by a Notification. Perhaps it's an issue that the Notification is a system thing, whereas the app widget is a home screen thing. Regardless, you could:

• Use getForegroundService(), as you have, or

• Try getBroadcast() with an explicit Intent, and with the BroadcastReceiver starting a JobIntentService, if you do not want to raise a Notification (as a foreground service requires)

Based on your symptoms, you appear to have tripped over what I would consider to be a bug: there should be a way to switch from getService() to getForegroundService() without having to reboot. :-) I'll try to run some experiments and will file an issue if I can reproduce the problem.