使用自己的IComparer＆LT; T＆GT;使用LINQ的OrderBy [英] Use own IComparer<T> with Linq OrderBy

问题描述

我有一个通用的

List<MyClass>

其中， MyClass的有一个属性

InvoiceNumber 包含值，例如：

where MyClass has a property InvoiceNumber which contains values such as:

一分之二十零万零九百零六结果
二分之二十零万零九百零六结果
..结果
十分之二十零万〇九百〇六结果
十一分之二十零万零九百零六结果
十二分之二十万○九百○六结果

200906/1
200906/2
..
200906/10
200906/11
200906/12

我的目录绑定到

BindingList<T>

它支持LINQ的排序：

which supports sorting with linq:

protected override void ApplySortCore(
           PropertyDescriptor property, ListSortDirection direction)
{

    _sortProperty = property;
    _sortDirection = direction;

    var items = this.Items;

    switch (direction)
    {
        case ListSortDirection.Ascending:
            items = items.OrderByDescending(x => property.GetValue(x)).ToList();
            break;
        case ListSortDirection.Descending:
            items = items.OrderByDescending(x => property.GetValue(x)).ToList();
            break;
    }

    this.Items = items;

}

但是默认的比较各种（像预想的那样）是这样的：

However the default comparer sorts (as supposed) like this:

一分之二十零万零九百零六结果
十分之二十零万〇九百〇六结果
十一分之二十零万零九百零六结果
十二分之二十万○九百○六结果
二分之二十零万零九百零六结果

200906/1
200906/10
200906/11
200906/12
200906/2

这是在这种情况下，讨厌

which is nasty in this case.

现在我想用我自己的的IComparer＆LT; T＆GT; 与此有关。它看起来是这样的：

Now I want to use my own IComparer<T> with this. It looks like this:

public class MyComparer : IComparer<Object>
{

    public int Compare(Object stringA, Object stringB)
    {
        String[] valueA = stringA.ToString().Split('/');
        String[] valueB = stringB.ToString().Split('/');

        if(valueA .Length != 2 || valueB .Length != 2)
             return String.Compare(stringA.ToString(), stringB.ToString());

        if (valueA[0] == valueB[0]) 
        {
          return String.Compare(valueA[1], valueB[1]);
        }
        else
        {
          return String.Compare(valueA[0], valueB[0]);
        }

    }

}

和改变了 ApplySortCore code使用该的IComparer ：

and changed the ApplySortCore code to use this IComparer:

case ListSortDirection.Ascending:
    MyComparer comparer = new MyComparer();
    items = items.OrderByDescending(
              x => property.GetValue(x), comparer).ToList();
    break;

在调试我的code，我看到 MyComparer.Compare（对象，对象）被多次调用，并返回正确的价值观（-1,0 1）为比较方法。

When I debug my code, I see that MyComparer.Compare(object, object) is called multiple times and returns the right values (-1, 0, 1) for a compare method.

但我的名单还在排序的错误的方式。我缺少的东西吗？我不知道。

But my list is still sorted the "wrong" way. Am I missing something? I have no clue.

推荐答案

您比较器看起来我错了。你还只是排序在默认的文本排序。当然，你要解析的两个数字和排序依据是：

Your comparer looks wrong to me. You're still just sorting in the default text ordering. Surely you want to be parsing the two numbers and sorting based on that:

public int Compare(Object stringA, Object stringB)
{
    string[] valueA = stringA.ToString().Split('/');
    string[] valueB = stringB.ToString().Split('/');

    if (valueA.Length != 2 || valueB.Length != 2)
    {
        stringA.ToString().CompareTo(stringB.ToString()));
    }

    // Note: do error checking and consider i18n issues too :)
    if (valueA[0] == valueB[0]) 
    {
        return int.Parse(valueA[1]).CompareTo(int.Parse(valueB[1]));
    }
    else
    {
        return int.Parse(valueA[0]).CompareTo(int.Parse(valueB[0]));
    }
}

（请注意，这不符合您的问题，说明你已经通过调试和验证是比较返回正确的值坐好 - 但恐怕我在这一方面怀疑人为错误）

(Note that this doesn't sit well with your question stating that you've debugged through and verified that Compare is returning the right value - but I'm afraid I suspect human error on that front.)

此外，斯文的权利 - 改变项值不改变你的绑定列表。你应该加上：

Additionally, Sven's right - changing the value of items doesn't change your bound list at all. You should add:

this.Items = items;

在你的方法的底部。

at the bottom of your method.

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