Map接口方法

Map map = new HashMap();
        map.put("邓超","孙俪");
        map.put("张三","王五");
        map.put("李四","赵六");
        map.put(null,"关七");

        System.out.println("map = " + map);

//        remove:根据键删除映射
        map.remove(null);
        System.out.println("map = " + map);
//        get：获取
        System.out.println( map.get("李四")); //赵六
//        size：获取个数
        System.out.println( map.size()); //3
//        isEmpty：判断是否为空
        System.out.println( map.isEmpty()); //F
//        clear：清空
        map.clear();
        System.out.println("map = " + map); //空
//        containsKey：查找建是否存在
        System.out.println("map = " + map.containsKey("张三")); //空