示例：

public static void main(String[] args) {        Map
    
      map = new HashMap
     
      ();        map.put("admin", "admin");        map.put("ytx", "ytx");        map.put("admin", "admin222");                for (String s : map.keySet()) {            System.out.println(s+"=="+map.get(s));        }    }输出结果：ytx==ytxadmin==admin
     
    

解决方案：HashMap用IdentityHashMap代替

Map<String, Object> map = new HashMap<String, Object>();

Map<String, Object> resultMap = new IdentityHashMap<String, Object>();

public static void main(String[] args) {        Map
    
      map = new IdentityHashMap
     
      ();        map.put("admin", "admin");        map.put("ytx", "ytx");        map.put(new String("admin"), "admin222");                for (String s : map.keySet()) {            System.out.println(s+"=="+map.get(s));        }    }输出结果：admin==admin222ytx==ytxadmin==admin
     
    

注：put的值必须是两个不同的对象