Need code example on how to run an Android service forever in the background even when device sleeping, like Whatsapp?

Question

I have tried various ways to achieve this, but my service eventually gets killed.

I want to use AlarmManager to trigger a class every one hour. Even if the device is

Answer 1

Request partial WakeLock.

 PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
mWakeLock = pm.newWakeLock(PowerManager.FULL_WAKE_LOCK, "My Tag");
mWakeLock.acquire();

onStartCommand retrun START_STICKY :

@Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        super.onStartCommand(intent, flags, startId); 
        return START_STICKY;
    }