我收到此错误（FileName.exe 中发生类型 'System.IndexOutOfRangeException' 的未处理异常）- 它由写入行函数发生

Question

Dim outputFile As IO.Path
Dim filepath As String = "PCPT2Database.txt"
'Append a new Entry into PCPT2Database
Private Sub btnSave_Click(sender As Object, e As EventArgs) Handles btnSave.Click
    'Declare variables
    Dim newNo As Integer = 0
    Dim NewEmail As String = 0
    Dim NewSurname As String = 0
    Dim NewName As String = 0
    Dim NewCell As Integer = 0
    'Defencive Programming

    If txtName.Text = "" Or IsNumeric(txtName.Text) Then
        MessageBox.Show("Please enter a Valid Name")
        txtName.Focus()
    Else : NewName = txtName.Text
    End If
    If txtSurname.Text = "" Or IsNumeric(txtSurname.Text) Then
        MessageBox.Show("Please enter a Valid Surname")
        txtSurname.Focus()

    Else : NewSurname = txtSurname.Text
    End If
    If txtEmail.Text = "" Or IsNumeric(txtEmail.Text) Then
        MessageBox.Show("Please enter a Valid Email")
        txtEmail.Focus()
    Else : NewEmail = txtEmail.Text
    End If
    If mtbCell.Text = "" Then
        MessageBox.Show("Please enter a 10 digit number")
        mtbCell.Focus()
    End If

    Dim filePath As String = "T2Database.txt"
    Dim intNewNo() As Integer = {}
    Dim intCount As Integer = 0
    Dim currentRow() As String

    Dim intLoop As Integer

    Using MyReader As New Microsoft.VisualBasic.FileIO.TextFieldParser(filePath)
        MyReader.TextFieldType = FileIO.FieldType.Delimited
        MyReader.SetDelimiters(",")

        While Not MyReader.EndOfData
            Try
                currentRow = MyReader.ReadFields()

                ReDim Preserve intNewNo(intCount)

                intNewNo(intCount) = currentRow(0)

                intCount = +1

            Catch ex As Microsoft.VisualBasic.FileIO.MalformedLineException
                MsgBox("line" & ex.Message & " Its not valid.")

            End Try
        End While
    End Using

    For intLoop = 0 To intCount + 1

    Next
    If IO.File.Exists(filePath) Then

        Using outputFile = IO.File.AppendText(filePath)
            outputFile.WriteLine**(Join({intNewNo(intLoop).ToString, txtName.Text, txtSurname.Text, mtbCell.Text, txtEmail.Text}, ","))**
        End Using

        MessageBox.Show("Save Successful")
        MessageBox.Show("Add another record", "Cancel", MessageBoxButtons.OKCancel, MessageBoxIcon.Information)

        txtName.Clear()
        txtSurname.Clear()
        mtbCell.Clear()
        txtEmail.Clear()
    Else
        MessageBox.Show(filePath, ".txt not found.",
                        MessageBoxButtons.RetryCancel, MessageBoxIcon.Information)
    End If
End Sub

Answer 1

单个方法中发生的事情太多了。将您的代码划分为具有单一目的的方法可以帮助您专注于该目的。我将代码分解为验证、读取、写入和清除。这大大简化了按钮代码。

可以使用 TryParse 方法和 String.IsNullOrEmpty 改进验证代码，但我没有管它。

在读取代码中，我使用了 List(Of T) 来累加值。这不需要您提供初始大小或使用 ReDim Preserve 添加数据。

intLoop 的唯一原因是在您的消息框中显示错误行的索引。

Write 代码在 For 循环中使用列表。我假设你的意思是用空的 For 循环来包围对文件的写入。我不明白你为什么要添加除了列表中的数字之外所有相同数据的记录。如果这是你想要的，那么在循环外解析连接一次，然后将数字添加到循环中的字符串。

Private Sub btnSave_Click(sender As Object, e As EventArgs) Handles btnSave.Click
    If Not IsInputValid() Then
        Exit Sub
    End If
    Dim filePath As String = "T2Database.txt"
    Dim intNewNo = ReadInputFile(filePath)
    If AppendToDataFile(intNewNo) Then
        MessageBox.Show("Save Successful")
        ClearTextBoxes()
    Else
        MessageBox.Show($"{filePath} not found.", "Save Failed", MessageBoxButtons.OK, MessageBoxIcon.Information)
    End If
End Sub

Private Function IsInputValid() As Boolean
    If txtName.Text = "" Or IsNumeric(txtName.Text) Then
        MessageBox.Show("Please enter a Valid Name")
        txtName.Focus()
        Return False
    End If
    If txtSurname.Text = "" Or IsNumeric(txtSurname.Text) Then
        MessageBox.Show("Please enter a Valid Surname")
        txtSurname.Focus()
        Return False
    End If
    If txtEmail.Text = "" Or IsNumeric(txtEmail.Text) Then
        MessageBox.Show("Please enter a Valid Email")
        txtEmail.Focus()
        Return False
    End If
    If mtbCell.Text = "" Then
        MessageBox.Show("Please enter a 10 digit number")
        mtbCell.Focus()
        Return False
    End If
    Return True
End Function

Private Function ReadInputFile(FullFilePath As String) As List(Of Integer)
    Dim filePath As String = "T2Database.txt"
    Dim lst As New List(Of Integer)
    Dim intLoop As Integer = 0
    Dim lines = File.ReadAllLines(filepath)
    Dim NewNum As Integer
    For Each line In lines
        If Integer.TryParse(line.Substring(0, line.IndexOf(","c)), NewNum) Then
            lst.Add(NewNum)
        Else
            MessageBox.Show($"Line Num {intLoop} containing{line} is not valid.")
        End If
        intLoop += 1
    Next
    Return lst
End Function

Private Function AppendToDataFile(intNewNo As List(Of Integer)) As Boolean
    Dim filepath As String = "PCPT2Database.txt"
    If IO.File.Exists(filepath) Then
        Using outputFile = File.AppendText(filepath)
            For Each number In intNewNo
                outputFile.WriteLine(Join({number.ToString, txtName.Text, txtSurname.Text, mtbCell.Text, txtEmail.Text}, ","))
            Next
        End Using
        Return True
    Else
        Return False
    End If
End Function

Private Sub ClearTextBoxes()
    txtName.Clear()
    txtSurname.Clear()
    mtbCell.Clear()
    txtEmail.Clear()
End Sub

抱歉，我没有机会测试此代码，所以可能会出现一些错误。如果您从文本文件中提供了一些示例数据，那会更容易。

我收到此错误（FileName.exe 中发生类型 'System.IndexOutOfRangeException' 的未处理异常）- 它由写入行函数发生

I get this error (An unhandled exception of type 'System.IndexOutOfRangeException' occurred in FileName.exe ) - it occurs by the write line function

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