Android checking whether the app is closed

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.

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(Kotlin example)

https://github.com/jshvarts/AppLifecycleDemo