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

  protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.YourxmlFileName);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    }

  public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();

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