我需要2的Comparer＆LT; T＆GT;用于在两个方向上分选？ [英] Do I need 2 Comparer<T> for sorting in both directions?

问题描述

如果我创建一个的Comparer＆LT; T＆GT; 进行排序一组对象而言，有一个简单的方法来'倒置'，所以我可以在排序另一个方向？或者，我需要定义一个第二的Comparer＆LT; T＆GT; 与测试的比较方法交换左右

解决方案

 公共类ReverseComparer＆LT; T＆GT; ：的Comparer＆LT; T＆GT;
{
    私人的Comparer＆LT; T＆GT; inputComparer;
    公共ReverseComparer（的Comparer＆LT; T＆GT; inputComparer）
    {
        this.inputComparer = inputComparer;
    }

    公众覆盖INT比较（T X，T Y）
    {
        返回inputComparer.Compare（Y，X）;
    }
}
 

这允许你做的是这样的：

  list.Sort（新ReverseComparer（someOtherComparer））;
 

If I create a Comparer<T> for the purposes of sorting a set of objects, is there a simple way to 'invert' it so I can sort in the other direction? Or do I need to define a 2nd Comparer<T> with the tests in the Compare method swapped around?

解决方案

public class ReverseComparer<T> : Comparer<T>
{
    private Comparer<T> inputComparer;
    public ReverseComparer(Comparer<T> inputComparer)
    {
        this.inputComparer = inputComparer;
    }

    public override int Compare(T x, T y)
    {
        return inputComparer.Compare(y, x);
    }
}

This allows you to do something like:

list.Sort(new ReverseComparer(someOtherComparer));

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