java4Android(22)Map/HashMap的方法：put()/set()

import java.util.Map;import java.util.HashMap;class test{    public  static void main(String[] args){        HashMap<String,String> hm = new HashMap<String,String>();        Map<String,String> map = hm;        map.put("1","a");        map.put("2","b");        map.put("3","c");        map.put("4","d");        //如果重复设置相同键的值，则该值被覆盖        map.put("2","e");        int i = map.size();        System.out.println(i);        String s = map.get("2");        System.out.println(s);    }   }

结果：
4
e