Java Movie Test

package com.#.movies;

import java.util.*;
import java.util.stream.Collectors;

public class MoviesAnalyzer {

    static class Movie {
        String title;
        String duration;
        List<String> actors;
        List<Integer> watchlist;
        List<Integer> favorites;
        List<Rating> ratings;
    }

    static class Rating {
        int userId;
        int rating;
    }

    static class User {
        int userId;
        String email;
        List<Integer> friends;
    }

    List<Movie> movies;

    List<User> users;

    public MoviesAnalyzer(List<Movie> movies, List<User> users) {
        this.movies = movies;
        this.users = users;
    }

    public List<String> topFavouriteMoviesAmongFriends(int userId) {

        List<String> movies = new ArrayList<>();
        HashMap<String, Long> ranking = new HashMap<>();
        Optional<User> user = findUser(userId);

        user.ifPresent(u -> this.movies.stream().forEach(movie -> {
            Long friendsRating = movie.favorites.stream()
                    .filter(favorite -> u.friends.contains(favorite)).count();
            ranking.put(movie.title, friendsRating);
        }));

        ranking.entrySet().stream()
                .sorted(Map.Entry.comparingByKey())
                .sorted(Map.Entry.comparingByValue(Comparator.reverseOrder()))
                .forEach(r -> movies.add(r.getKey()));


        return movies.subList(0, 3);
    }

    private Optional<User> findUser(int userId) {
        for(int i = 0; i < this.users.size(); i++) {
            if (this.users.get(i).userId == userId) {
                return Optional.of(this.users.get(i));
            }
        }
        return Optional.empty();
    }

}