@Override
  protected final void fireIntervalAdded(Object source, int index0, int index1) {
    super.fireIntervalAdded(source, index0, index1);

    if (getSize() == 1 && getSelectedItem() == null) {
      setSelectedItem(getElementAt(0));
    }
  }
@Override
  protected final void fireIntervalAdded(Object source, int index0, int index1)