Destroy Activity stack

Question

There are some applications in which you can logout at any point within. e.g you login and then your browse around. you use the action bar or the menu button to logout. I can call finish() at that very point but then it will just pop the last activity. Even if i move the user forward to the Home Activity, still the stack remains in memory. Is there any way to destroy the remaining stack?

Answer 1

The easiest way to do this is to clear the stack back to your home or first activity, and pass an identifier saying to exit the app. For example:

public class ActivityOne extends Activity {
    public static final String FINISH_THIS = "FINISH_THIS";
    @Override
    protected void onNewIntent(Intent intent) {
        super.onNewIntent(intent);
        if(intent.hasExtra(FINISH_THIS)) {
            finish();
        }
    }
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if(getIntent().hasExtra(FINISH_THIS)) {
            finish();
        }
    }
}

public class ActivityTwo extends Activity {
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if(item.getItemId() == R.id.logout) {
            Intent intent = new Intent(this, ActivityOne.class);
            intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
            intent.putExtra(ActivityOne.FINISH_THIS, true);
            startActivity(intent);
        }
        return true;
    }
}

If ActivityOne is the root of your stack and ActivityTwo is where the user selected the option to logout, starting an intent that clears back to ActivityOne will get rid of the backstack. If you want the app to exit when logging out, you can pass an extra like I did with FINISH_THIS to signal the root/home activity to finish.

Another way to do this would be to call setResult(FINISH_THIS) where FINISH_THIS is an int identifier before calling finish(). Then in all other activities in the stack, you'd override onActivityResult and check the result to see if that activity needs to be finished. If it does, you set the result again and keep passing it down the line.

Using the intent method I outlined in the beginning is the preferred method for clearing the stack as it doesn't rely on daisy chaining results together but both options work well enough.

Answer 2

A quick and dirty way to do it would be onResume verify you are still logged in, if not then finish it. That way if they hit back, it will close each activity as it tries to open them. This would also prevent someone from using the app manager to re-enter your activity when you expect it to be closed.

Another idea would be read Android: Clear the back stack