C# de>IEqualityComparer方法有一个优点：您可以为HashSet提供不同的相等比较器，根据域或其他情况定义什么是相等对象……我想您的意思是：public List RatingList=new List（）；public List Movie

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de>IEqualityComparer方法有一个优点：您可以为

HashSet

提供不同的相等比较器，根据域或其他情况定义什么是相等对象……我想您的意思是：public List RatingList=new List（）；public List MovieList=新列表（）；的确，我做到了。固定的！

string[] users = new string[5] { "David", "Matt", "Ben", "Chris", "Torri" };
string[] movies = new string[4] { "Titanic", "X-men", "Snatch", "Speed"};
ratings = new int[5, 4];

// Note I'm going to use HashSet<T> everywhere because both movies and
// users should be unique in their respective collections

public class User 
{
    public sealed class UserEqualityComparer : IEqualityComparer<User>
    {
          public bool Equals(User a, User b)
          {
              return a != null && b != null && a.Name == b.Name;
          }

          public int GetHashCode(User some)
          {
              return some.Name.GetHashCode();
          }
    }


     public string Name { get; set; }

     // C# 6 expression bodied properties!!!!
     public HashSet<Movie> LikesMovies { get; set; } = new HashSet<Movie>(new Movie.MovieEqualityComparer());
}

public class Movie
{   
    public sealed class MovieEqualityComparer : IEqualityComparer<Movie>
    {
          public bool Equals(Movie a, Movie b)
          {
              return a != null && b != null && a.Name == b.Name;
          }

          public int GetHashCode(Movie some)
          {
              return some.Name.GetHashCode();
          }
    }

     public string Name { get; set; }

     // C# 6 expression bodied properties!!!!
     public HashSet<User> UsersWhoLikeIt { get; set; } = new HashSet<User>(new User.UserEqualityComparer());
}

HashSet<Movie> movies = new HashSet<Movie>(new Movie.MovieEqualityComparer())
{
    new Movie { Name = "Star Trek" },
    new Movie { Name = "Star Wars" }
};

HashSet<User> users = new HashSet<User>(new User.UserEqualityComparer())
{
    new User { Name = "John" },
    new User { Name = "Jack" }
};

// Now an user likes a movie:
Movie movie = movies.Single(some => some.Name == "Star Trek");
User user = users.Single(some => some.Name == "John");

// You need to associate both sides of the whole M-N association:
// A movie can be liked by many users and an user can like many movies...
movie.UsersWhoLikeIt.Add(user);
user.LikesMovies.Add(movie);

public class User
{
    public string Name { get; set; }
}

public class Movie
{
    public string Title { get; set; }
}

public class Rating
{
    public User RatingUser { get; set; }
    public Movie RatingMovie { get; set; }
}

public List<User> UserList = new List<User>();
public List<Movie> MovieList = new List<Movie>();
public List<Ratings> RatingList = new List<Rating>();

UserList.Add(new User() { Name = "David"} );
UserList.Add(new User() { Name = "Matt"} );
UserList.Add(new User() { Name = "Ben"} );
UserList.Add(new User() { Name = "Chris"} );
UserList.Add(new User() { Name = "Torri"} );

MovieList.Add(new User() { Title = "Titanic"} );
MovieList.Add(new User() { Title = "X-men"} );
MovieList.Add(new User() { Title = "Snatch"} );
MovieList.Add(new User() { Title = "Speed"} );

ratings = new byte[5, 4];

ratingtable:    
int userID  PK   
int movieID  PK   
byte rating