How to resume activity instead of restart when going “up” from action bar

Question

I have two activities. Say Activity A and Activity B.
From Activity A I click a button to launch Activity B

Answer 1

You can also achieve the same outcome programatically

Intent upIntent = NavUtils.getParentActivityIntent(this);
upIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
NavUtils.navigateUpTo(this, upIntent);