获取map的key的名称

Map<String, String> map = new HashMap<String, String>();
map.put("xiaocui1", "gongchen");
map.put("xiaocui2", "daima");
map.put("xiaocui3", "xuexi");
map.put("xiaocui4", "dagong");

System.out.println(map.keySet());

输出：
[xiaocui4, xiaocui1, xiaocui2, xiaocui3]