Using actionbar home as up button, home activity saveInstanceState is always null

Question

Activity A ===click button===> Activity B

When press back button, Activity A is not recreated.

When press home as up button, Activity A is recreated.

So

Answer 1

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    // Respond to the action bar's Up/Home button
    case android.R.id.home:
        finish();
        return true;
    }
    return super.onOptionsItemSelected(item);
}

I used finish() insteed of NavUtils;