App resumes to wrong activity when singleTask flag is used

Question

MainActivity in my app has launchMode set to singleTask. If I start ActivityB from MainActivity, then put app to background and start my app from applications screen it does not resume correctly. ActivityB automatically finishes and MainActivity resumes. I expect ActivityB to resume instead. Why is this happening and what could I do to make it work normally? It works OK without singleTask flag but I need that flag for other purposes.

By the way, my app resumes correctly from recent apps screen.

Are you sure you do not call finish() in onPause() / onResume() method in ActivityB ? — Martin Pohorský, Aug 22 '16 at 13:20

score 0 · Answer 1 · answered Aug 22 '16 at 13:34

0

Use the following code in the LAUNCHER Activities.

@Override
protected void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

if (!isTaskRoot()) {
    finish();
    return;
}

// Rest of your onCreate code goes here
}

answered Aug 22 '16 at 13:34

Dmarp

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score 0 · Answer 2 · answered Aug 22 '16 at 13:48

Activity B is closed because it launched from Activity A, this is normal behavior for android because Activity A needs to be restarted (singleTask) and all related instance will be kill/finish.

So, what you can do is implement shared-preference.

your activity A should be like this :

public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //// read share preference
    SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
    int defaultValue = getResources().getInteger("MYSHARE_PRFERENCE");
    int isOpened = sharedPref.getInt("IS_ACTIVITY_B_ALREADY_OPENED", defaultValue);

    if (isOpened == 1)
    {
        //resume activity B
        startActivity(new Intent(MainActivity.this, ActivityB.class));
    }       
    ////

    findViewById(R.id.text).setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            startActivity(new Intent(MainActivity.this, ActivityB.class));

            //// write on share preference
            SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
            SharedPreferences.Editor editor = sharedPref.edit();
            editor.putInt("IS_ACTIVITY_B_ALREADY_OPENED", 1);
            editor.commit();
            ////
        }
    });
}

}

P.S : I didn't compile it yet, the code might be error on compile. But share preference can be solution for your problem.

Thanks for your effort to help, but starting ActivityB from MainActivity does not resume it. Activity state is lost. Apparently this problem doesn't have a solution. This question has already been asked here http://stackoverflow.com/questions/2417468/android-bug-in-launchmode-singletask-activity-stack-not-preserved — Egis, Aug 22 '16 at 14:33

App resumes to wrong activity when singleTask flag is used

2 Answers2