Visual Basic If Then 错误

Question

我有一个 VB 项目，我正在尝试使用一些 VBA 代码来定位基于 Excel 表的第一列的重复行，并创建一个“1”标志，但是在 VB 中使用时 VBA 代码给出了错误：

InvalidCastException 未处理 重载解析失败，因为无法使用以下参数调用 Public ''： '公共共享运算符 (a As String, b As String) As Boolean': 参数匹配参数 'a' 无法从 '__ComObject' 转换为 'String'。

Public Sub btnRun_Click(sender As System.Object, e As System.EventArgs) Handles btnRun.Click

    Dim xlApp As Excel.Application
    Dim xlWorkBook1 As Excel.Workbook ' Interactions
    Dim xlWorkBooks As Excel.Workbooks
    Dim MainSheet1 As Excel.Worksheet

    xlApp = New Excel.Application
    xlWorkBooks = xlApp.Workbooks
    xlWorkBook1 = xlWorkBooks.Open(File1_name)
    xlApp.Visible = False

    MainSheet1 = xlWorkBook1.Sheets(1)
    MainSheet1.Activate()

    Dim InteractionRows As Long = MainSheet1.UsedRange.Rows.Count ' Total number of rows in the Interaction worksheet
    Dim Duplicate_Found_Index As Long ' Stores all match index values for duplicate interactions
    Dim Duplicate_ID As Long ' Defining the first column to loop through and match duplicate interactions

    ' **** Duplicate Interaction ****
    ' Flag Creation
    For Duplicate_ID = 1 To (InteractionRows)
        If MainSheet1.Cells(Duplicate_ID, 1) <> "" Then 'checking if the cell is having any item, skipping if it is blank.
            Duplicate_Found_Index = xlApp.WorksheetFunction.Match(MainSheet1.Cells(Duplicate_ID, 1), MainSheet1.Range("A1:A" & InteractionRows), 0) 'getting match index number for the value of the cell.
            If Duplicate_ID <> Duplicate_Found_Index Then 'if the match index is not equals to current row number, then it is a duplicate value
                MainSheet1.Cells(Duplicate_ID, 34) = "1" ' Print the flag "1" in the 34th column if duplicate found
            Else
                MainSheet1.Cells(Duplicate_ID, 34) = "0" ' Print the flag "0" in the 34th column if no duplicate
            End If
        End If
    Next
End Sub

任何帮助都将非常感谢您了解为什么会发生此错误

Answer 1

当单元格为空白时，调用 MainSheet1.Cells(Duplicate_ID, 1) 给出 Nothing (null)。所以不要将它与字符串匹配，而是检查它的空值。

If MainSheet1.Cells(Duplicate_ID, 1) IsNot Nothing Then

End If

Answer 2

使用IsNot 代替<>

            If Duplicate_ID IsNot Duplicate_Found_Index Then 'if the match index is not equals to current row number, then it is a duplicate value
                MainSheet1.Cells(Duplicate_ID, 34) = "1" 
            Else
                MainSheet1.Cells(Duplicate_ID, 34) = "0" 
            End If