2021-11-05

本文章主要对集合中的重复数据进行去重。

public class Distinct {
    public static void main(String[] args) {
        User user1 = new User();
        User user2 = new User();
        User user3 = new User();
        user1.setId(1);
        user2.setId(2);
        user3.setId(3);
        user1.setName("李1");
        user2.setName("李1");
        user3.setName("李3");
        List userList = List.of(user1, user2, user3);

        //java11
        List repeatList = List.of("我", "我", "是", "是", "李", "二", "李", "二", "狗", "狗");

        userList.forEach(
                i -> System.out.print(i.getId() + "-" + i.getName() + " ")
        );
        repeatList.forEach(
                System.out::print
        );

        System.out.println("n================去重后================");

		//filter()里面只要返回boolean，逻辑可以自己写
        repeatList = repeatList.stream().distinct().collect(Collectors.toList());
        Set userName = new HashSet<>();
        userList = userList.stream().filter(
                i -> {
                    if (!userName.contains(i.name)) {
                        userName.add(i.name);
                        return true;
                    }
                    return false;
                }
        ).collect(Collectors.toList());

        userList.forEach(
                i -> System.out.print(i.getId() + "-" + i.getName() + " ")
        );
        repeatList.forEach(
                System.out::print
        );

    }

    static class User {
        Integer id;
        String name;
        //GET、SET
    }
}