更改应用时调用的活动onResume（）

Question

I would like to know if there's a way to differentiate when the onResume() method of an activity is called from the same app or a different application.

For example I would like to differentiate when my main activity's onResume() is called when I return to the app from Whatsapp or another activity of my app.

I know there's a way to do it with GET_TASKS permission but that method is deprecated and not recommended.

Thank you

Answer 1

It appears you want to know when app comes from the background to foreground in each Activity . This can be achieved using a class that extends the Application class and implements the ActivityLifecycleCallbacks interface. Firstly, here's the code for this class:

public class MyApplication extends Application implements ActivityLifecycleCallbacks {

    public boolean appInBackground;
    private Handler mHandler;  

    ...  

    @Override   
    public void onActivityResumed(Activity activity) {
        Log.i("Activity Resumed", activity.getLocalClassName());

        mHandler.cancelCallbacksAndMessages(null);  
        appInBackground = false;
    }   

    @Override   
    public void onActivityPaused(Activity activity) {
        Log.i("Activity Paused", activity.getLocalClassName());

        mHandler.postDelayed(new Runnable() {
             @Override  
             public void run() {  
                  appInBackground = true;
             }  
        }, 5000);  
    }   

    ...  

} 

If you notice in above code we are basically giving the app a grace period of 5 seconds to switch from one activity to other. If it exceeds more than that, it means the app was in background. The above class will need to registered in the <application> tag of your manifest file under android:name:"" property as android:name:"MyApplication" .

To use this in your activity, override the onPause() :

private boolean resumedFromBg;

@Override
protected void onPause() {
    super.onPause();
    resumedFromBg = ((MyApplication) getApplication()).appInBackground;
}

Let me know if you run into any issues~