Find out whether the current activity will be task root eventually, after pending finishing activities have disappeared

Question

If FirstActivity is the root of the task, and it finishes itself and launches SecondActivity, then calling isTaskRoot() in SecondActivity immediately will return false, because the FirstActivity's finishing happens asynchronously and thus isn't done yet. Waiting for a second and then calling isTaskRoot() returns true.

public class FirstActivity extends Activity {     @Override     public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         finish();         startActivity(new Intent(this, SecondActivity.class));     } } 

public class SecondActivity extends Activity {     public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.main);     }      @Override     protected void onResume() {         super.onResume();         ((TextView)findViewById(R.id.tv1))                 .setText("isTaskRoot() in onResume(): " + isTaskRoot());         new Handler().postDelayed(new Runnable() {             @Override             public void run() {                 ((TextView)findViewById(R.id.tv2))                         .setText("isTaskRoot() after 1s: " + isTaskRoot());             }         }, 1000);     } } 

Is there a way to …

• (optimally) find out whether the activity will be the task root eventually, or,

• (better than nothing) get some sort of notification/callback once the task is in its "final" state and thus isTaskRoot() will return the "truth"?

Answer 1

I've had a similar problem and I wanted tight control over exactly who the root activity is. In my case, the root could only be one of my own activities (not 3rd party ones), so I was able to use the following approach:

I extended the Application class, added a weak reference to an activity called currentRootActivity and added synchronized getter and setter.

Then I managed this state by myself when activities were created / destroyed. My use case was a little special because I was looking to replace one root with another, so I knew exactly where to reset my new state variable, but I'm pretty sure you can do the same.

I was even able to add this state logic in a shared base class for all of my activities. So this wasn't as disgusting as it sounds :)

As mentioned in the comments, the activity method isFinishing might also come in handy.