Android foreground and background listener and manager

Application.java

public class MyApplication extends Application {

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

    private void initComponents() {
        BackgroundManager.init(this);
        
        BackgroundManager.get().registerListener(new BackgroundManager.Listener() {
            @Override
            public void onBecameForeground() {
                
            }

            @Override
            public void onBecameBackground() {

            }
        });
    }
}

BackgroundManager.java

public class BackgroundManager implements Application.ActivityLifecycleCallbacks {

    public static final long BACKGROUND_DELAY = 500;

    private static BackgroundManager sInstance;

    public interface Listener {
        void onBecameForeground();

        void onBecameBackground();
    }

    private boolean mInBackground = true;
    private final List<Listener> listeners = new ArrayList<>();
    private final Handler mBackgroundDelayHandler = new Handler();
    private Runnable mBackgroundTransition;

    public static BackgroundManager init(Application application) {
        if (sInstance == null) {
            sInstance = new BackgroundManager(application);
        }
        return sInstance;
    }

    public static BackgroundManager get() {
        if (sInstance == null) {
            throw new RuntimeException("Use BackgroundManager.init before");
        }
        return sInstance;
    }

    private BackgroundManager(Application application) {
        application.registerActivityLifecycleCallbacks(this);
    }

    public void registerListener(Listener listener) {
        if (!listeners.contains(listener))
            listeners.add(listener);
    }

    public void unregisterListener(Listener listener) {
        listeners.remove(listener);
    }

    public boolean isInBackground() {
        return mInBackground;
    }

    @Override
    public void onActivityResumed(Activity activity) {
        if (mBackgroundTransition != null) {
            mBackgroundDelayHandler.removeCallbacks(mBackgroundTransition);
            mBackgroundTransition = null;
        }

        if (mInBackground) {
            mInBackground = false;
            notifyOnBecameForeground();
        }
    }

    private void notifyOnBecameForeground() {
        for (Listener listener : listeners) {
            try {
                listener.onBecameForeground();
            } catch (Exception e) {
            }
        }
    }

    @Override
    public void onActivityPaused(Activity activity) {
        if (!mInBackground && mBackgroundTransition == null) {
            mBackgroundTransition = new Runnable() {
                @Override
                public void run() {
                    mInBackground = true;
                    mBackgroundTransition = null;
                    notifyOnBecameBackground();
                }
            };
            mBackgroundDelayHandler.postDelayed(mBackgroundTransition, BACKGROUND_DELAY);
        }
    }

    private void notifyOnBecameBackground() {
        for (Listener listener : listeners) {
            try {
                listener.onBecameBackground();
            } catch (Exception e) {
            }
        }
    }

    @Override
    public void onActivityStopped(Activity activity) {
    }

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

    @Override
    public void onActivityStarted(Activity activity) {
    }

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

    @Override
    public void onActivityDestroyed(Activity activity) {
    }

}