java list 對象根據某個字段去重的方法

 List<User> lists = new ArrayList<>();
        for (int i = 0; i < 40000; i++) {
            if (i%2 == 0){
                lists.add(new User("aa1",1));
            }else {
                lists.add(new User("aa2",2));
            }

        }
        lists = lists.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(
                () -> new TreeSet<>(Comparator.comparing(User::getAge))), ArrayList::new));
        for (int i = 0; i < lists.size(); i++) {
            System.out.println(lists.get(i).getName());
        }