c# - .NET 中只允许唯一项的集合？

Question

C# 中是否有一个集合不允许您向其中添加重复项？例如，愚蠢的类

public class Customer {
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Address { get; set; }

    public override int GetHashCode() {
        return (FirstName + LastName + Address).GetHashCode();
    }

    public override bool Equals(object obj) {
        Customer C = obj as Customer;
        return C != null && String.Equals(this.FirstName, C.FirstName) && String.Equals(this.LastName, C.LastName) && String.Equals(this.Address, C.Address);
    }
}

下面的代码(显然)会抛出一个异常:

Customer Adam = new Customer { Address = "A", FirstName = "Adam", LastName = "" };
Customer AdamDup = new Customer { Address = "A", FirstName = "Adam", LastName = "" };

Dictionary<Customer, bool> CustomerHash = new Dictionary<Customer, bool>();
CustomerHash.Add(Adam, true);
CustomerHash.Add(AdamDup, true);

但是是否有一个类可以类似地保证唯一性，但没有 KeyValuePairs？我以为HashSet<T>会那样做，但阅读文档后，类似乎只是一个集合实现(看图)。

Answer 1

HashSet<T>是你要找的。来自 MSDN (强调):

The HashSet<T> class provides high-performance set operations. A set is a collection that contains no duplicate elements, and whose elements are in no particular order.

请注意 HashSet<T>.Add(T item) method返回 bool -- true如果该项目已添加到集合中； false如果该项目已经存在。