取多条数据相同用户时间最小的那条数据

    public static void main(String[] args) {
        List<User> list = new ArrayList<User>();
        list = Arrays.asList(
                new User("小强", 11, "男", "2022-10-10"),
                new User("小玲", 15, "女", "2022-10-10"),
                new User("小虎", 23, "男", "2022-10-10"),
                new User("小雨", 26, "女", "2022-10-08"),
                new User("小飞", 19, "男", "2022-10-14"),

                new User("小雨", 26, "女", "2022-10-10"),
                new User("小强", 15, "女大", "2022-10-12"),
                new User("小玲", 16, "女大", "2022-10-12"),
                new User("小虎", 25, "男大", "2022-10-12"),
                new User("小雨", 28, "女大", "2022-10-12")
        );
//        List collect = list.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(
//                Comparator.comparing(worth -> worth.getName()))), ArrayList::new));
//        System.out.println("collect = " + collect);
//
//        User user = list.stream().min(Comparator.comparing(User::getAge)).get();
//        System.out.println("user = " + user);
//        System.out.println("collect = " + collect);
//

        // 步骤一：将数据进行分组
        Map<String, List<User>> name = list.stream().collect(Collectors.groupingBy(e -> e.getName()));
        // 步骤二：获取分组中最近日期数据，然后汇总到List中 collect(Collectors.toList());
        List<User> time1 = name.values().stream().map(maps -> {
            Optional<User> time = maps.stream().min(Comparator.comparing(ee -> DateUtil.parse(ee.getBirthday(), "yyyy-MM-dd")));
            // 这句的意思是如果time有值就返回，如果没值就返回null
            return time.orElse(null);
        }).collect(Collectors.toList());
        System.out.println("time1 = " + time1);

        List<User> time2 = name.values().stream().map(maps -> {
            Optional<User> time = maps.stream().min(Comparator.comparing(ee -> DateUtils.getMillis(DateUtil.parse(ee.getBirthday(), "yyyy-MM-dd"))));
            // 这句的意思是如果time有值就返回，如果没值就返回null
            return time.orElse(null);
        }).collect(Collectors.toList());
        System.out.println("time2 = " + time2);
    }
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