Dictionary.ContainsKey返回False，但要真 [英] Dictionary.ContainsKey return False, but a want True

问题描述

namespace Dic
{
public class Key
{
    string name;
    public Key(string n) { name = n; }
}

class Program
{
    static string Test()
    {
        Key a = new Key("A");
        Key b = new Key("A");
        System.Collections.Generic.Dictionary<Key, int> d = new System.Collections.Generic.Dictionary<Key, int>();
        d.Add(a, 1);
        return d.ContainsKey(b).ToString();
    }

    static void Main(string[] args)
    {
        System.Console.WriteLine(Test());
    }
}
}

我应该改变，以获得正确的？

What should I change to get true?

推荐答案

您想要真正的 - 但A和B是不同的对象

You want true - but a and b are different objects.

您需要重写GetHash code和等于阶级键

You need to override GetHashCode and Equals on class Key

public class Key
{
    string name;
    public Key(string n) { name = n; }

    public override int GetHashCode()
    {
        if (name == null) return 0;
        return name.GetHashCode();
    }

    public override bool Equals(object obj)
    {
        Key other = obj as key;
        return other != null && other.name == this.name;
    }
}

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