Object type collections are de duplicated according to the value of an attribute

Go straight to the code , Ha ha ha

public class RemoveDuplicateTest {


    public static void main(String[] args) {

        List<User> userList = new ArrayList<>();
        userList.add(new User("zs", 19, 80.0));
        userList.add(new User("zs", 18, 76.0));
        userList.add(new User("lisi", 20, 70.0));
        userList.add(new User("zs", 21, 90.0));
        userList.add(new User("lisi", 22, 60.0));
        userList.add(new User("wangwu", 18, 86.0));

        int num = 0;
        for (User user : userList) {
            System.out.println(user);
            num++;
        }
        System.out.println(" Quantity before weight removal : " + num);

        //  Press name Attribute de duplication 

        //  Conventional writing 
        Set<String> nameSet = new HashSet<>();
        List<User> resList = new ArrayList<>();
        for (User user : userList) {
            if (!nameSet.contains(user.getName())) {
                resList.add(user);
            }
            nameSet.add(user.getName());
        }
        int num2 = 0;
        for (User user : resList) {
            System.out.println(user);
            num2++;
        }
        System.out.println(" Quantity after weight removal : " + num2);

        //  Use jdk8 New feature writing 
        List<User> resList2 = userList.stream().collect(Collectors.collectingAndThen(
                Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(User::getName))), ArrayList::new
        ));
        for (User user : resList2) {
            System.out.println(user);
        }

    }


}

The key is jdk8 How to write new features

//  Use jdk8 New feature writing 
        List<User> resList2 = userList.stream().collect(Collectors.collectingAndThen(
                Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(User::getName))), ArrayList::new
        ));