当键不是简单的基本类型时使用ContainsKey()

Question

我的Dictionary的ContainsKey()方法不起作用 - 如何"覆盖GetHashCode()"使其工作？

Answer 1

您必须覆盖两者GetHashCode()并Equals()指示等效性.例如:

public sealed class MyType : IEquatable<MyType> {
    private readonly int foo;
    private readonly string bar;
    public int Foo { get { return foo; } }
    public string Bar { get { return bar; } }

    public MyType(int foo, string bar) {
        this.foo = foo; this.bar = bar;
    }
    public bool Equals(MyType other) {
       if(other == null) return false;
       return other.foo == this.foo && other.bar == this.bar;
    }
    public override bool Equals(object other) {
       return Equals(other as MyType);
    }
    public override int GetHashCode() {
       int result = 29;
       result = result * 13 + foo.GetHashCode();
       result = result * 13 + (bar == null ? 0 : bar.GetHashCode());
       return result;
    }
}

请注意,这IEquatable<T>完全是可选的,但对于避免使用框的结构特别有用.注意:如果定义相等的部分是不可变的,它将使生命更加健全.