public int compare(T a, T b) {
   return CUtil.getStringCompare().compare(a.getID() + "", b.getID() + "");
 }
 public void refresh() {
   scene.getWorld().processEvent();
   Vector<T> units = scene.getWorld().getChilds(unit_type);
   CUtil.sort(units, this);
   list.setListData(units);
 }