for(int i=0;i List l = list.get(i); for(Object o:l){ if(o instanceof User){User user = (User) o; System.out.println(user); } if(o instanceof Department){Department dep = (Department) o; System.out.println(dep); } }}
两两做比较是什么意思，是前后两个还是所有的都要相互比较一次呢
