AllActivitiesLifecycleExample

public class MyAppActivityCallbacks implements Application.ActivityLifecycleCallbacks {
    private Set<Class<Activity>> visibleActivities = new HashSet<>();

    @Override
    public void onActivityResumed(Activity activity) {
        visibleActivities.add((Class<Activity>) activity.getClass());
    }

    @Override
    public void onActivityStopped(Activity activity) {
         visibleActivities.remove(activity.getClass());
    }

    public boolean isAnyActivityVisible() {
        return !visibleActivities.isEmpty();
    }

    @Override
    public void onActivityCreated(Activity activity, Bundle savedInstanceState) {}

    @Override
    public void onActivityStarted(Activity activity) {}

    @Override
    public void onActivityPaused(Activity activity) {}

    @Override
    public void onActivityDestroyed(Activity activity) {}

    @Override
    public void onActivitySaveInstanceState(Activity activity, Bundle outState) {}
}


class App extends Application{
@Override
    public void onCreate() {
    registerActivityLifecycleCallbacks(myAppActivityCallbacks);
    }
}