类集框架Map

package su;import java.util.Map;import java.util.HashMap;public class Test{    public static void main(String args[]){        Map<Integer , String> map = new HashMap<Integer , String>();        map.put(1, "a");        map.put(2, "a");//value的值可以重复        map.put(3, "s");        map.put(4, "y");        map.put(2, "c");//KEY重复会导致value覆盖        System.out.println(map.get(1));        System.out.println(map.get(2));    }}