获取Map的key值的几种方式

参考：获取Map的key值的几种方式

调用keySet方法

@Test
public void getKeys1(){
    Map<String, Object> map = new HashMap<>();
    map.put("name","曹操");
    map.put("sex","男");
    map.put("age","21");
    System.out.println("map.keySet():"+map.keySet());
    Iterator<String> iterator = map.keySet().iterator();
    while (iterator.hasNext()){
        System.out.println("iterator:"+iterator.next());
    }
    Set<String> keySet = map.keySet();
    // 遍历keySet，并输出key的值
    for(String key : keySet){
        System.out.println(key+":"+map.get(key).toString());
    }
}

entrySet()

@Test
public void getKeys2(){
    Map<String, Object> map = new HashMap<>();
    map.put("name","曹操");
    map.put("sex","男");
    map.put("age","21");
    //第二种
    System.out.println("map.entrySet():"+map.entrySet());
    Iterator<Map.Entry<String, Object>> iterator = map.entrySet().iterator();
    while (iterator.hasNext()){
        System.out.println("iterator:"+iterator.next());
    }
    for (Map.Entry<String, Object> entry : map.entrySet()){
        System.out.println("key:"+entry.getKey()+";value:"+entry.getValue());
    }
}