所有活动开始之前和所有活动停止之后的监听器？

Question

If I want to run some scripts before any activity starts and after all activity stops, Where would I put such a listener in android?

Ive considered putting it in the Android Application class, and simply put the methods inside its onCreate and onSaveInstanceState - but I am not sure they get called before and after all activites

Answer 1

Unfortunately in the Application class there is no callback when the application has stopped, but I think you can try this code:

<< here was old code >>

Updated : Code of Application class:

public class MyApplication extends Application {

    @Override
    public void onCreate() {
        super.onCreate();
        startService(new Intent(this, Monitor.class));
    }
}

The code of background service:

public class Monitor extends Service implements Application.ActivityLifecycleCallbacks {

    private static final String TAG = "Monitor";

    int mActivitiesCount = 1; // At the moment when service started, the main Activity is already opened

    public Monitor() {
    }

    @Override
    public void onCreate() {
        super.onCreate();
        getApplication().registerActivityLifecycleCallbacks(this);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        return START_STICKY;
    }

    @Override
    public void onDestroy() {
        getApplication().unregisterActivityLifecycleCallbacks(this);
        super.onDestroy();
    }

    @Override
    public void onActivityCreated(Activity activity, Bundle bundle) {
        mActivitiesCount++;
        Log.d(TAG, "onActivityCreated: count: " + mActivitiesCount);
    }

    @Override
    public void onActivityStarted(Activity activity) {

    }

    @Override
    public void onActivityResumed(Activity activity) {

    }

    @Override
    public void onActivityPaused(Activity activity) {

    }

    @Override
    public void onActivityStopped(Activity activity) {

    }

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

    }

    @Override
    public void onActivityDestroyed(Activity activity) {
        mActivitiesCount--;
        Log.d(TAG, "onActivityDestroyed: count: " + mActivitiesCount);
        if (mActivitiesCount == 0) {
            Log.d(TAG, "All activities was destroyed");
            // do something
        }
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}