C# List去重的比较器

public class user_collection_DistinctBy_userId : IEqualityComparer<User>
    {

        public bool Equals(User x, User y)
        {
            if (x.UserId == y.UserId)
            {
                return true;
            }
            else
            {
                return false;
            }
        }

        public int GetHashCode(User obj)
        {
            return 0;
        }
    }