How do I detect if the user has left my app?

Question

I am developing an Android app and I want to detect when the user exits my app either by clicking the Back button or the Home button.

Also, an event like onInit() would be useful in my scenario, as I just want to have the MyInıt action start at first.

onDestroy() is not called until other apps need more memory.

Answer 1

Note: This only works if your target is >= API14

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You can also use Application.registerActivityLifecycleCallbacks() and when any activity pauses post a delayed Runnable (that will invoke when user lefts app) to Handler. When activities are created/started/resumed you remove that Runnable from Handler. So when you navigate inside your app you always cancel that Runnable, but if another activity not from your app is activated - the Runnable will be invoked.

I used this to logout user when he lefts my app, here's code for callbacks:

public class MyApplication extends Application implements Application.ActivityLifecycleCallbacks {      private Handler handler;     private Runnable runLogout = new Runnable() {         @Override         public void run() {             //logoutUser()         }     };      @Override     public void onCreate() {         super.onCreate();          registerActivityLifecycleCallbacks(this);         handler = new Handler(getMainLooper());     }      @Override     public void onActivityCreated(Activity activity, Bundle savedInstanceState) {         handler.removeCallbacks(runLogout);     }      @Override     public void onActivityStarted(Activity activity) {         handler.removeCallbacks(runLogout);     }      @Override     public void onActivityResumed(Activity activity) {         handler.removeCallbacks(runLogout);     }      @Override     public void onActivityPaused(Activity activity) {         handler.postDelayed(runLogout, 1000);     }      @Override     public void onActivityStopped(Activity activity) {      }      @Override     public void onActivitySaveInstanceState(Activity activity, Bundle outState) {      }      @Override     public void onActivityDestroyed(Activity activity) {      } } 

However, Runnable will run not in the context of activity lifecycle, so to use this in activity you would need to set and check some application-wide flag or broadcast an intent.