Is there a way to make AppCompat's ActionBar's "back/up" button act as the "back" system button

Question

I have an app with a couple of activities. Until now I had a "hardcoded" hierarchy between them, so I had the android:parentActivityName set explicitly in each (but the launcher activity) of them. However now I added the Settings to the menu of more than one activity.

Is there a way to make the "back" arrow in the action bar function as the system's back button (in the bottom of the screen)? In other words: if there's a parentActivityName set, then it goes back to the parent activity, if not, then it closes the activity and "goes back" to the previous activity.

This is what I tried, but doesn't work. If I don't call actionBar.setDisplayHomeAsUpEnabled(true), then there's no "back" arrow in the action bar, but if I call it in an activity that doesn't have parentActivityName set in the Manifest, then I get an exception when I click the arrow.

abstract public class BaseActivity extends ActionBarActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(getLayoutResourceId());

        final ActionBar actionBar = getSupportActionBar();
        if (null != actionBar) {
            actionBar.setDisplayHomeAsUpEnabled(getDisplayHomeAsUpEnabled());
        }
    }

    protected abstract int getLayoutResourceId();
    abstract protected boolean getDisplayHomeAsUpEnabled();

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        final int id = item.getItemId();
        if (id == android.R.id.home) {
            NavUtils.navigateUpFromSameTask(this);
            return true;
        }
    }
}

Answer 1

Try :

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

The code above will call your onBackPressed, so be wary if you overrided it. Otherwise, it will be same like the "back" system button.