使用一个对象作为一个通用的字典关键 [英] Using an object as a generic Dictionary key

问题描述

如果我想使用对象作为密钥的词典，我需要重写，使他们在一个特定的方式来比较有什么方法呢？

If I want to use objects as the keys for a Dictionary, what methods will I need to override to make them compare in a specific way?

说我有一个一类具有的属性：

Say I have a a class which has properties:

class Foo {
    public string Name { get; set; }
    public int FooID { get; set; }

    // elided
} 

和我想创建一个：

Dictionary<Foo, List<Stuff>>

我想富对象具有相同 FooID 被认为是同一组。我需要在富类重写哪些方法？

I want Foo objects with the same FooID to be considered the same group. Which methods will I need to override in the Foo class?

要总结一下：我想分类的东西对象到列表中，由富对象分组。 的东西的对象将有一个 FooID 来将它们链接到其类别。

To summarize: I want to categorize Stuff objects into lists, grouped by Foo objects. Stuff objects will have a FooID to link them to their category.

推荐答案

在默认情况下，这两种重要的方法是 GetHash code（）和等于（）。重要的是，如果两件事情是相等的（等于（）返回true），它们具有相同的散列code。例如，你可能回归FooID;作为 GetHash code（）如果你想，随着比赛。你也可以实施 IEquatable＆LT;富＆GT; ，但这是可选的：

By default, the two important methods are GetHashCode() and Equals(). It is important that if two things are equal (Equals() returns true), that they have the same hash-code. For example, you might "return FooID;" as the GetHashCode() if you want that as the match. You can also implement IEquatable<Foo>, but that is optional:

class Foo : IEquatable<Foo> {
    public string Name { get; set;}
    public int FooID {get; set;}

    public override int GetHashCode() {
        return FooID;
    }
    public override bool Equals(object obj) {
        return Equals(obj as Foo);
    }
    public bool Equals(Foo obj) {
        return obj != null && obj.FooID == this.FooID;
    }
}

最后，另一种选择是提供一个的IEqualityComparer＆LT; T＆GT; 做同样的

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