Java如何开发一个简易的电影评分与推荐系统

class User {
    int userId;
    String name;
    public User(int userId, String name) {
        this.userId = userId;
        this.name = name;
    }
}

class Movie {
    int movieId;
    String title;
    String genre;
    public Movie(int movieId, String title, String genre) {
        this.movieId = movieId;
        this.title = title;
        this.genre = genre;
    }
}

class Rating {
    int userId;
    int movieId;
    int score; // 1-5
    public Rating(int userId, int movieId, int score) {
        this.userId = userId;
        this.movieId = movieId;
        this.score = score;
    }
}

public List<Movie> recommendByGenre(int userId) {
    // 获取用户所有评分
    List<Rating> userRatings = ratings.stream()
        .filter(r -> r.userId == userId)
        .toList();

    // 计算用户对各类型的平均分
    Map<String, Double> genreScores = new HashMap<>();
    Map<String, Integer> genreCount = new HashMap<>();

    for (Rating r : userRatings) {
        Movie m = movies.get(r.movieId);
        if (m != null) {
            genreScores.put(m.genre, genreScores.getOrDefault(m.genre, 0.0) + r.score);
            genreCount.put(m.genre, genreCount.getOrDefault(m.genre, 0) + 1);
        }
    }

    // 找出用户最喜欢的类型
    String favoriteGenre = null;
    double maxAvg = 0;
    for (String genre : genreScores.keySet()) {
        double avg = genreScores.get(genre) / genreCount.get(genre);
        if (avg > maxAvg) {
            maxAvg = avg;
            favoriteGenre = genre;
        }
    }

    // 推荐该类型中未评分的高分电影
    return movies.values().stream()
        .filter(m -> m.genre.equals(favoriteGenre))
        .filter(m -> userRatings.stream().noneMatch(r -> r.movieId == m.movieId))
        .sorted((a, b) -> Double.compare(getAverageRating(b.movieId), getAverageRating(a.movieId)))
        .limit(5)
        .toList();
}

System.out.println("1. 评分电影  2. 查看推荐  3. 退出");
int choice = scanner.nextInt();