从嵌套列表中获取最大值并使用stream转换为一个列表

Question

 class Player {
        private int score;

        public int getScore() {
            return score;
        }
    }

    class Team {
        private List<Player> players;

        public List<Player> getPlayers() {
            return players;
        }
    }

    class League {
        private List<Team> teams;

        public List<Team> getTeams() {
            return teams;
        }
    }

 public  List<Player> getTopPlayersFromEachTeam(List<Team> league) {
        // implementation
    }

league.stream().map(Team::getPlayers).collect(Collectors.toList())

Answer 1

code>Team类可以具有BestPlayer方法

public Player bestPlayer() {
    return players.stream().max(Comparator.comparing(Player::getScore)).orElseThrow();
}

在联赛中，每支球队都很容易选出最佳球员：

public List<Player> getTopPlayersFromEachTeam() {
    return this.teams.stream().map(Team::bestPlayer).collect(Collectors.toList());
}

或一体机

public List<Player> getTopPlayersFromEachTeam() {
    return this.teams.stream()
            .map(t -> t.getPlayers().stream().max(Comparator.comparing(Player::getScore)).orElseThrow())
            .collect(Collectors.toList());
}

code>.orelsethrow()代码只是表示如果找不到max球员，例如一个队的球员列表为空

League l = new League(Arrays.asList(
        new Team(Arrays.asList(new Player(1), new Player(2), new Player(3))),
        new Team(Arrays.asList(new Player(10), new Player(20), new Player(30))),
        new Team(Arrays.asList(new Player(100), new Player(200), new Player(300)))
));

System.out.println(l.getTopPlayersFromEachTeam()); // [Player{score=3}, Player{score=30}, Player{score=300}]