Android AlertDialog突出显示默认值？

Question

说你有

public class PickerFragment extends DialogFragment { 
    public Dialog onCreateDialog(Bundle savedInstanceState) {

         AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
         //.....
         return builder.create();
}

我将默认值设置为1，如何突出显示它以便打开它的人会看到第1项被选中？提前谢谢。