对象型的集合按某个属性的值进行去重

直接上代码吧, 哈哈哈

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("去重前数量: " + num);

        // 按name属性去重

        // 常规写法
        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("去重后数量: " + num2);

        // 使用jdk8新特性写法
        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);
        }

    }


}

重点是jdk8新特性的写法

// 使用jdk8新特性写法
        List<User> resList2 = userList.stream().collect(Collectors.collectingAndThen(
                Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(User::getName))), ArrayList::new
        ));