Enabling Up (ancestral) navigation in Android apps is straightforward for the typical case: just specify parent activities in the manifest and send setDisplayHomeAsUpEnabled(true). But non-typical cases (like dynamic parents) require extra steps.

Today I implemented some non-typical cases and experimented with overriding action bar callbacks, tweaking the back stack, etc. But in most cases I simply wanted up navigation to behave like back navigation whenever there was no fixed parent defined. For that, I developed a simple recipe:

@Override
public boolean onOptionsItemSelected(MenuItem item) {
	switch (item.getItemId()) {
		case android.R.id.home:
			if (NavUtils.getParentActivityName(getActivity()) != null) {
				NavUtils.navigateUpFromSameTask(getActivity());
			} else {
				getActivity().onBackPressed();
			}
			return true;
		default:
			return super.onOptionsItemSelected(item);
	}
}