ContentObserver registered in service is killed when app killed

Question

I need to be able to detect when changes occur in contact data (any type of change to any contact in the address book).

I am using this ContentObserver:

public class ContactsContentObserver extends ContentObserver {
private Context context;
private Handler toastMessageHandler;

public ContactsContentObserver(Handler handler, Context ctx) {
    super(handler);
    context = ctx;
}

@Override
public void onChange(boolean selfChange) {
    this.onChange(selfChange,null);
}

@Override
public void onChange(boolean selfChange, Uri uri) {
    // Change Detected! Do something.
}

}

I register this observer in a service like this:

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

private void registerContactsContentObserver(){
    ContactsContentObserver myObserver = new ContactsContentObserver(new Handler(), this);
    getContentResolver().registerContentObserver(ContactsContract.Contacts.CONTENT_URI, true, myObserver);
}

I start this service in my main activity.

It works fine as long as the activity is open (even if in the background), and the onChange() method is called every time I change any contact data.

But it doesn't work at all if I manually close the app by clearing it from recent apps in android

Am I doing something wrong? Isn't the service supposed to run even when the app is closed?

Answer 1

I've been able to solve the issue with the help of pskink

Starting the service in the forground like this:

private void runAsForeground(){
    Intent notificationIntent = new Intent(this, LauncherActivity.class);
    PendingIntent pendingIntent=PendingIntent.getActivity(this, 0,
            notificationIntent, PendingIntent.FLAG_ONE_SHOT);

    Notification notification=new NotificationCompat.Builder(this)
            .setSmallIcon(R.mipmap.ic_launcher)
            .setContentText("test")
            .setContentIntent(pendingIntent).build();

    startForeground(1, notification);

}

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

solved the issue.

Although, I still don't understand why the issue occurred in the first place, since, the service is sticky and supposed to run even if the app is closed. Even if android stopped the service to save memory, it is supposed to restart it.

Can somebody explain to me why starting the service in the foreground is any different than a regular sticky service in the background?