1.values&keySet

map.values()方法获取所有值的集合

map.keySet()方法获取所有键的集合

eg:

public static void main(String[] args) {
    Map m=new HashMap();
    m.put(1,"a");
    m.put(2,"b");
    m.put(3,"c");
    m.put(4,"d");
    System.out.println("获取所有value:"+m.values());
    System.out.println("获取所有key:"+m.keySet());
}

输出结果：

java Map_javaSE