错误 11 类型“System.Collections.Generic.List(Of String)”的值无法转换为“String 的 1 维数组”。

这个错误通常是由于类型不匹配造成的。在这段代码中，String.Join方法需要一个字符串数组作为输入参数，而updatedLines是一个List(Of String)类型的对象。要解决这个错误，可以使用List(Of String)对象的ToArray方法将其转换为字符串数组，或者直接使用String类的Join方法来避免这个问题：

使用List(Of String)对象的ToArray方法：

Private Sub Button2_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button2.Click
    Dim comboBoxValue As String = ComboBox1.Text
    Dim filePath As String = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "abc.txt")

    If File.Exists(filePath) Then
        Dim existingText As String = File.ReadAllText(filePath)
        Dim lines() As String = existingText.Split(Environment.NewLine.ToCharArray(), StringSplitOptions.RemoveEmptyEntries)
        Dim updatedLines As New List(Of String)()

        For Each line As String In lines
            If Not line.StartsWith(comboBoxValue & ",") Then
                updatedLines.Add(line)
            End If
        Next

        File.WriteAllText(filePath, String.Join(Environment.NewLine, updatedLines.ToArray()))
        MessageBox.Show("已成功删除文本文件中对应的行。")
    Else
        MessageBox.Show("文本文件不存在。")
    End If
End Sub

直接使用String类的Join方法：

Private Sub Button2_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button2.Click
    Dim comboBoxValue As String = ComboBox1.Text
    Dim filePath As String = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "abc.txt")

    If File.Exists(filePath) Then
        Dim existingText As String = File.ReadAllText(filePath)
        Dim lines() As String = existingText.Split(Environment.NewLine.ToCharArray(), StringSplitOptions.RemoveEmptyEntries)
        Dim updatedLines As New List(Of String)()

        For Each line As String In lines
            If Not line.StartsWith(comboBoxValue & ",") Then
                updatedLines.Add(line)
            End If
        Next

        File.WriteAllText(filePath, String.Join(Environment.NewLine, updatedLines))
        MessageBox.Show("已成功删除文本文件中对应的行。")
    Else
        MessageBox.Show("文本文件不存在。")
    End If
End Sub