HashSet.SetEquals 在两个相同的集合上 returns false

Question

我有两个 HashSet<T> collections containing the same items (that is, different instances of the objects but with the same values). From my understanding of the SetEquals 方法下面的代码应该 return true 因为集合项属性值是相等的，但是它 returns false:

var source = new HashSet<AllocatedComponent>()
        {new AllocatedComponent() {
            Weighting = 100,
            ComponentId = 1, 
            Title = "Foo"}};
    
var destination = new HashSet<AllocatedComponent>()
        {new AllocatedComponent() {
            Weighting = 100,
            ComponentId = 1, 
            Title = "Foo"}};
    
Console.WriteLine(source.SetEquals(destination)); // False

任何人都可以解释一下我在这里做错了什么吗？我的目标是检查这两个集合是否包含相同数量的项目，以及相同的属性值。

我不太了解 Microsoft 文档的备注部分，因此可能忽略了一些非常明显的内容。

Net Fiddle here

Answer 1

从第一条评论开始让框架使用它们的数据比较对象，您必须重写 2 个方法 bool Equals(object o) 和 int GetHashCode()。下面的代码给出了期望的结果（请注意，您必须为这两个实现使用所有数据成员）

using System;
using System.Collections.Generic;

public class AllocatedComponent
 
{
    public double Weighting { get; set; }
    public int ComponentId { get; set; }
    public string Title { get; set; }
    
    public override bool Equals(object o)
    {
        if(!(o is AllocatedComponent))
           return false;
        AllocatedComponent ac = (AllocatedComponent)o;
        return ac.Title == this.Title && ac.ComponentId == this.ComponentId && ac.Weighting == this.Weighting;
    }   
    public override int GetHashCode()
    {
        return this.Title.GetHashCode();
    }
}

public class Program
{
    public static void Main()
    {
        var source = new HashSet<AllocatedComponent>()
            {new AllocatedComponent() {
                Weighting = 100,
                ComponentId = 1, 
                Title = "Foo"}};
        
        var destination = new HashSet<AllocatedComponent>()
            {new AllocatedComponent() {
                Weighting = 100,
                ComponentId = 1, 
                Title = "Foo"}};
        
        Console.WriteLine(source.SetEquals(destination)); // False
    }
}

HashSet.SetEquals 在两个相同的集合上 returns false

HashSet.SetEquals on two identical collections returns false

c#

.net

hashset