How Google calendar or Instagram make their apps all the time up and running even after force stop

Question

Looks like force stop should prevent app from running and it\'s even disable all app\'s alarms. However I found that notification in Google Calendar still shown fine even after

Answer 1

If you start a service in Application Class than your service will be always running even though if a user terminates or force stop from task manager, it will run again.

To create service specifically in Android studio Right click on app from Project Explorer and then New > Service > Service

Create a service:

public class ServiceName extends Service {

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
    return null;
  }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
      // do your jobs here
      return super.onStartCommand(intent, flags, startId);
        }
    } 

Now create an Application Class and start Service in Application Class

public class App extends Application {

    @Override
    public void onCreate() {
        super.onCreate();

        startService(new Intent(this, ServiceName.class));
    }
}