（VB.NET）根据多个属性查找对象列表中的所有重复项

Question

我有一个我创建的CommissionStatement对象列表。我需要创建一个新列表，它只包含基于3个属性的列表中的重复项：Firm;供应商;和总数（即这3个中的每一个必须在2个或更多个对象中相同才能被识别为副本）

Object目前是一个简单的字符串对象。

Private Class CommissionStatement
    Property Provider As String
    Property Firm As String
    Property Source As String
    Property Media As String
    Property Total As String
    Property Received As String
End Class

我有一份所有CommissionStatments的清单如下：

Dim fileLocation As String = importText.Text
        Dim csvText As String = My.Computer.FileSystem.ReadAllText(fileLocation).Replace(", ", " ") 
        Dim providerString As String = ""
        Dim allStatements = New List(Of CommissionStatement)
        Dim countIndex As Integer = 0, maxIndex As Integer = csvText.Split(vbLf).Length
        For Each line As String In csvText.Split(vbLf)
            '' Remove the top row
            countIndex += 1
            If countIndex = 1 Then
                Continue For
            End If
            statementProgress.Value = ((countIndex / maxIndex) * 100)
            '' Build the New commissionStatement object and add it to the allStatements list
            If Not line = "" Then
                Dim commissionStatement = New CommissionStatement
                With commissionStatement
                    .Provider = line.Split(",")(0)
                    .Firm = line.Split(",")(1)
                    .Source = line.Split(",")(2)
                    .Media = line.Split(",")(3)
                    .Total = line.Split(",")(4)
                End With
                providerString &= commissionStatement.Provider & ","
                allStatements.Add(commissionStatement)
            End If
        Next

StackOverflow上的第一篇帖子很抱歉，如果它不是很清楚！重复列表还需要是一个CommissionStatements列表，其中包含基于Firm Provider和Total

的allStatements列表中的重复项

Answer 1

最好的办法是使用lambda表达式。以下功能应该按照您的要求进行。

Private Function GetDuplicateCommisionStatements(tempStatement As CommissionStatement) As List(Of CommissionStatement)
    Return allStatements.FindAll(Function(x) x.Firm = tempStatement.Firm And x.Provider = tempStatement.Provider And x.Total = tempStatement.Total)
End Function

并像这样使用..

duplicatelist = GetDuplicateCommisionStatements(testCommisionStatement)

当然使用您自己的对象名称。

顺便提一下，您可以使用With语句缩短sub，如下所示

Private Function GetDuplicateCommisionStatements(tempStatement As CommissionStatement) As List(Of CommissionStatement)
    With tempStatement
        Return allStatements.FindAll(Function(x) x.Firm = .Firm And x.Provider = .Provider And x.Total = .Total)
    End With
End Function