if (comp == null) return;  if (comp instanceof Container)
updateComponentTreeUIImpl(comp); if (comp instanceof JComponent)
  public static void updateComponentTreeUI(Component comp)  {    if (comp == null)      return;        if (comp instanceof Container)      {        Component[] children = ((Container)comp).getComponents();        for (int i = 0; i < children.length; ++i)          updateComponentTreeUI(children[i]);      }    if (comp instanceof JComponent)      ((JComponent)comp).updateUI();  }