Android checking whether the app is closed

Question

I have an android application i need one function or any broadcast receiver that can check if the app is closed.. i don't need to call on destroy in every activity (there is about 20 activity into the app) i tried to add this function in Application class

public class ApplicationLifeCycleManager implements ActivityLifecycleCallbacks {

/** Manages the state of opened vs closed activities, should be 0 or 1.
 * It will be 2 if this value is checked between activity B onStart() and
 * activity A onStop().
 * It could be greater if the top activities are not fullscreen or have
 * transparent backgrounds.
 */
private static int visibleActivityCount = 0;

/** Manages the state of opened vs closed activities, should be 0 or 1
 * because only one can be in foreground at a time. It will be 2 if this
 * value is checked between activity B onResume() and activity A onPause().
 */
private static int foregroundActivityCount = 0;

/** Returns true if app has foreground */
public static boolean isAppInForeground(){
    return foregroundActivityCount > 0;
}

/** Returns true if any activity of app is visible (or device is sleep when
 * an activity was visible) */
public static boolean isAppVisible(){
    return visibleActivityCount > 0;
}

public void onActivityCreated(Activity activity, Bundle bundle) {
}

public void onActivityDestroyed(Activity activity) {
    Log.wtf("destroyed","app closed!!");
}

public void onActivityResumed(Activity activity) {
    foregroundActivityCount ++;
}

public void onActivityPaused(Activity activity) {
    foregroundActivityCount --;
}

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

public void onActivityStarted(Activity activity) {
    visibleActivityCount ++;
}

public void onActivityStopped(Activity activity) {
    visibleActivityCount --;
}
}

Also i have registered in on create in Application class

@Override
public void onCreate() {
    super.onCreate();
    registerActivityLifecycleCallbacks(new ApplicationLifeCycleManager());
}

but the onPaused and onResumed and onDestroyed function is called when i switch between activity: because it detects whether any activity is closed or destroyed or even resumed

so any solution to check whether the app is closed in one function??

Answer 1

This answer uses ProcessLifecycleOwner to detect application visibility.

which is a part of Android Architecture Component .

---

1. add this lib to your project

implementation "android.arch.lifecycle:extensions:1.1.1"

2. Extend an application class that implements LifecycleObserver

public class AppController extends Application implements LifecycleObserver {


///////////////////////////////////////////////
    @OnLifecycleEvent(Lifecycle.Event.ON_START)
    public void onEnterForeground() {
        Log.d("AppController", "Foreground");
        isAppInBackground(false);
    }
    @OnLifecycleEvent(Lifecycle.Event.ON_STOP)
    public void onEnterBackground() {
        Log.d("AppController", "Background");
        isAppInBackground(true);
    }
///////////////////////////////////////////////



    // Adding some callbacks for test and log
    public interface ValueChangeListener {
        void onChanged(Boolean value);
    }
    private ValueChangeListener visibilityChangeListener;
    public void setOnVisibilityChangeListener(ValueChangeListener listener) {
        this.visibilityChangeListener = listener;
    }
    private void isAppInBackground(Boolean isBackground) {
        if (null != visibilityChangeListener) {
            visibilityChangeListener.onChanged(isBackground);
        }
    }
    private static AppController mInstance;
    public static AppController getInstance() {
        return mInstance;
    }

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

        mInstance = this;

        // addObserver
        ProcessLifecycleOwner.get().getLifecycle().addObserver(this);
    }

}

And use it like this:

AppController.getInstance().setOnVisibilityChangeListener(new ValueChangeListener() {
    @Override
    public void onChanged(Boolean value) {
        Log.d("isAppInBackground", String.valueOf(value));
    }
});

Don't forget to add application name into your manifest

<application
    android:name="myPackageName.AppController"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"">

Done.

---

(Kotlin example)

https://github.com/jshvarts/AppLifecycleDemo