package chapter1;
public class ItemComparer implements Comparable
{
	public int compare(Object obj1,Object obj2)
    {
    	if ((obj1 instanceof Item) && (obj2 instanceof Item))
          {
          	Item item1 = (Item)obj1;
            Item item2 = (Item)obj2;
            return item1.ID.compareTo(item2.ID);
}
  else
  return -1;
}
}