KEY值可以重复的Map

public static void main(String[] args) {
	Map<String,String> map = new IdentityHashMap<String, String>();
	map.put(new String("a"), "1");
	map.put(new String("b"), "2");
	map.put(new String("c"), "3");
	map.put(new String("a"), "4");
	System.out.println(map);//{c=3, b=2, a=4, a=1}
}

public static void main(String[] args) {
	Map<Str