按对象属性对对象列表进行排序 [英] Sort List(of Object) by object properties

问题描述

我正在尝试实现已经给出答案的目标.但这是在 c#中，而且我对 c#都不了解，所以我正在寻找vb.net的替代方案.

I'm trying to achieve something where the answer is already given for. But it's in c# and I don't have any knowledge what-so-ever over c# so I'm looking for a vb.net alternative.

我制作了一个名为 BomItem 的 class ，它具有一些属性，例如数量，描述等.

I made a class called BomItem which has several properties like quantity, description etc.

我将这些 BomItems 添加到 BomItem的列表中，但是现在我想根据属性对它们进行排序.如何根据 ItemNumber 属性对项目进行排序?

I add these BomItems into a List(of BomItem) but now I would like to sort them according to a property. How can you sort the items based on the ItemNumber property?

这是链接找到我找到的 c#解决方案.

Here is the link to the c# solution I found.

我的班级代码

Public Class BomItem
    Public Property ItemNumber As String
    Public Property Description As String
    Public Property Quantity As Double
    Public Property Material As String
    Public Property Certificate As String
End Class

我如何添加 BomRow 对象

    _NewBomList.Add(New BomItem() With {
                    .ItemNumber = oRow.ItemNumber,
                    .Description = oPropSet.Item("Description").Value,
                    .Quantity = oRow.TotalQuantity,
                    .Material = oPropSet.Item("Material").Value,
                    .Certificate = CustomPropertySet.Item("Cert.").Value})

比较器

Public Class NaturalSort

Implements IComparer

Public Function Compare(ByVal x As Object,
            ByVal y As Object) As Integer Implements IComparer.Compare

    ' [1] Validate the arguments.
    Dim s1 As String = x
    If s1 = Nothing Then
        Return 0
    End If

    Dim s2 As String = y
    If s2 = Nothing Then
        Return 0
    End If

    Dim len1 As Integer = s1.Length
    Dim len2 As Integer = s2.Length
    Dim marker1 As Integer = 0
    Dim marker2 As Integer = 0

    ' [2] Loop over both Strings.
    While marker1 < len1 And marker2 < len2

        ' [3] Get Chars.
        Dim ch1 As Char = s1(marker1)
        Dim ch2 As Char = s2(marker2)

        Dim space1(len1) As Char
        Dim loc1 As Integer = 0
        Dim space2(len2) As Char
        Dim loc2 As Integer = 0

        ' [4] Collect digits for String one.
        Do
            space1(loc1) = ch1
            loc1 += 1
            marker1 += 1

            If marker1 < len1 Then
                ch1 = s1(marker1)
            Else
                Exit Do
            End If
        Loop While Char.IsDigit(ch1) = Char.IsDigit(space1(0))

        ' [5] Collect digits for String two.
        Do
            space2(loc2) = ch2
            loc2 += 1
            marker2 += 1

            If marker2 < len2 Then
                ch2 = s2(marker2)
            Else
                Exit Do
            End If
        Loop While Char.IsDigit(ch2) = Char.IsDigit(space2(0))

        ' [6] Convert to Strings.
        Dim str1 = New String(space1)
        Dim str2 = New String(space2)

        ' [7] Parse Strings into Integers.
        Dim result As Integer
        If Char.IsDigit(space1(0)) And Char.IsDigit(space2(0)) Then
            Dim thisNumericChunk = Integer.Parse(str1)
            Dim thatNumericChunk = Integer.Parse(str2)
            result = thisNumericChunk.CompareTo(thatNumericChunk)
        Else
            result = str1.CompareTo(str2)
        End If

        ' [8] Return result if not equal.
        If Not result = 0 Then
            Return result
        End If
    End While

    ' [9] Compare lengths.
    Return len1 - len2

End Function

End Class

推荐答案

使用 LINQ OrderBy :

_NewBomList.OrderBy(Function(bi) bi.ItemNumber)

以及降序:

_NewBomList.OrderByDescending(Function(bi) bi.ItemNumber)

如果要在字符串中使用数字顺序，则必须先将其转换为整数:

If you want a numeric order in your string you have to convert it to an integer first:

_NewBomList.OrderBy(Function(bi) Integer.Parse(bi.ItemNumber))

修改:
要为OrderBy扩展名提供自定义 IComparer ，您必须创建一个实现 IComparer(Of String)的类，其中String是要比较的 ItemNumbers :

To provide a custom IComparer for the OrderBy extension you have to create a class which implements IComparer(Of String) where String are your ItemNumbers to compare:

 Class ItemNumberComparer  
     Implements IComparer(Of String)

     Public Function Compare(String x, String y)
         Dim ix As String() = x.Split("."C)
         Dim iy As String() = y.Split("."C)

         Dim maxLen As Integer = Math.Max(ix.Length, iy.Length)
         For i As Integer = 0 To maxLen - 2
             If ix.Length >= i AndAlso iy.Length >= i Then
                If Integer.Parse(ix(i)) < Integer.Parse(iy(i)) Then
                   Return -1 'If x.i is LT y.i it must be smaller at all
                ElseIf Integer.Parse(ix(i)) > Integer.Parse(iy(i)) Then
                   Return 1 'If x.i is GT y.i it must be bigger all
                End If
             End If
         Next
         'This code is only executed if x and y differ at last number or have different ´number of dots
        If ix.Length = iy.Length Then
            Return Integer.Parse(ix(ix.Length - 1)).CompareTo(Integer.Parse(iy(iy.Length - 1))) 'Only last number differs
       Else
           Return ix.Length.CompareTo(iy.Length) 'The number with more dots is smaller
       End If

     End Function     
  End Class

通话语法:

Dim comparer = new ItemNumberComparer()
_NewBomList.OrderByDescending(Function(bi) bi.ItemNumber, comparer)

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