GetHashCode()经常重写冲突方式 [英] GetHashCode() override coliding way to often

问题描述

我使用的是unity，而unity中没有元组，因此我创建了自己的元组类，因为我的Dictionary需要它.

I'm using unity, and unity does not have a tuple in it, so I created my own tuple class to work since I needed it for my Dictionary.

Dictionary <Tuple<int,int>, Tile>

我创建的平铺类，与解决该问题并没有真正的联系(至少我认为这无济于事).

Tile class that I created and isn't really relevant to solve this problem(at least I think it wont help).

但是问题是我在元组中同时使用了负整数和正整数，并且当我将当前的 GetHashCode()与 Tuples 一起使用时，有时得到相同的HashCode，例如 Tuple< -10，8> 和 Tuple< -9，-10> 都在我返回哈希码时给出-172.

But the problem is that I'm using both negative and positive integer in my tuples, and when I use my current GetHashCode() with the Tuples, sometimes I get the same HashCode, for example Tuple<-10, 8> and Tuple<-9,-10> both gives -172 when I return the hashcode.

是否有任何好的GetHashCode不会让我发生冲突?老实说，我只使用运算符 == ，因为我需要检查两个元组内部是否具有相同的整数，如果我能得到运算符 == 只有在两个整数相同且顺序相同时发生冲突，才可以解决我的问题.

Is there any good GetHashCode that wouldn't get me conflicts? To be honest I'm only using the operator ==, because I need to check if both tuples have the same integers inside of them, if I could get a operator == that only collides when both integer are the same and in the same order, it would solve my problem.

在其他一些小问题上，我无法理解Equals替代方法，因为它确实可以正常工作，但是我不知道它的效果如何，因为我一直在更改每件事，直到它起作用为止.

Some other minor problems, I can't get to understand the Equals override, as it is, it is working, but I don't know how well it works, since I kind of changed every single thing until it worked.

public class Tuple<T1, T2>
{
    public T1 First { get; private set; }
    public T2 Second { get; private set; }

    public Tuple(T1 _First, T2 _Second)
    {
        First = _First;
        Second = _Second;
    }
    public override int GetHashCode()
    {
        int hash = 0;

        hash = First.GetHashCode() * 17 + Second.GetHashCode() + First.GetHashCode();

        return hash;
    }
    public static bool operator==(Tuple<T1, T2> obj1, Tuple<T1, T2> obj2)
    {
        if (ReferenceEquals(null, obj2))
            return false;
        return (obj1.GetHashCode() == obj2.GetHashCode());
    }
    public static bool operator!=(Tuple<T1, T2> obj1, Tuple<T1, T2> obj2)
    {
        if (ReferenceEquals(null, obj2))
            return true;
        return !(obj1.GetHashCode() == obj2.GetHashCode());
    }
    public bool Equals(Tuple<T1, T2> other)
    {
        if (other == null)
            return false;

        if (GetHashCode() == other.GetHashCode())
            return true;
        else
            return false;

    }
    public override bool Equals(object obj)
    {
        if (ReferenceEquals(null, obj))
        {
            return false;
        }
        if (ReferenceEquals(this, obj))
        {
            return true;
        }

        Tuple<T1, T2> other = obj as Tuple<T1, T2>;

        return obj.GetType() == GetType() && Equals(other);
    }
}
public static class Tuple
{
    public static Tuple<T1, T2> New<T1, T2>(T1 first, T2 second)
    {
        var tuple = new Tuple<T1, T2>(first, second);
        return tuple;
    }
}

推荐答案

GetHashCode()不应冲突.您应该使用它来确定两个事物可能是否是相同的对象，然后您必须进行彻底的检查以查看它们是否相同.

GetHashCode() isn't supposed to be collision free. You should use it to determine if two things might be the same objects, and then you have to actually do a thorough check to see if they are.

例如，您的==方法应更像这样编写:

For example, your == method should be written more like this:

public static bool operator==(Tuple<T1, T2> obj1, Tuple<T1, T2> obj2)
{
    if (ReferenceEquals(null, obj2))
        return false;

    if (obj1.GetHashCode() != obj2.GetHashCode())
    {
        return false;
    }
    return DefaultComparer<T1>.Equals(obj1.First, obj2.First) && DefaultComparer<T2>.Equals(obj1.Second, obj2.Second);
}

此外，不要忘记考虑 obj1 和 obj2 均为 null 的情况.

Also, don't forget to consider the case where obj1 and obj2 are both null.

如果要实现自己的 Tuple ，则可以考虑只是从

If you're implementing your own Tuple, you might consider just stealing Microsoft's from the Reference Source repository, or at least use it as a base for your own.

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