List分組后獲取第一條數據

用戶實體

@Data
@AllArgsConstructor
public class User {
    private Integer id;
    private String name;
    private Integer score;
}

根據name分組，獲取每組最大分數對應的一條數據。

    public static void main(String[] args) {
        List<User> list=new ArrayList<>();
        list.add(new User(1,"kobe",20));
        list.add(new User(2,"james",40));
        list.add(new User(3,"durant",20));
        list.add(new User(4,"kyrie",30));
        list.add(new User(5,"paul",20));
        list.add(new User(6,"james",50));
        list.add(new User(7,"paul",40));
        list.add(new User(8,"james",30));
        list.add(new User(9,"paul",50));
        list.add(new User(10,"kyrie",55));
        list.add(new User(11,"james",60));
        list.add(new User(12,"kobe",70));
        list.add(new User(13,"wade",55));
        list.add(new User(14,"durant",59));
        list.add(new User(15,"kobe",45));
        list.add(new User(16,"kyrie",55));

       Map<String, User> collect = list.stream().sorted((u1, u2) -> u2.getScore() - u1.getScore()).collect(Collectors.groupingBy(User::getName, 
 Collectors.collectingAndThen(Collectors.toList(), value -> value.get(0))));
        ArrayList<User> users = new ArrayList<>(collect.values());
        users.forEach(System.out::println);
    }

利用java8 的stream流來處理，先將score倒序，然后按name分組，然后選取第一條數據。

結果