Android - Back button in the title bar

Question

In many apps (Calendar, Drive, Play Store) when you tap a button and enter a new activity, the icon in the title bar turns into a back button, but for the app I am making, i

Answer 1

use this code

 @Override
 public void onCreate(Bundle savedInstanceState) {
    ...
   getActionBar().setDisplayHomeAsUpEnabled(true);
 } 

after that write this code in onOptionsItemSelected method

  int id = item.getItemId();

     if (id==android.R.id.home) {
        finish();
    }