索引超出了数组的范围 [VB.NET]

Question

您好，我是 VB 新手，正在学习中。这个错误有时会发生，有时不会发生，我觉得很奇怪。 我收到错误Index was outside the bounds of the array，它指向Button30.Text = Split(newestversion, vbCrLf)(**1**)

我的动机是从在线托管的文本文件中逐行读取。 例如，

label1.text = line 1 of the text file
label2.text = line 2 of the text file

这正是我想要的。

这是我当前的代码（已编辑）：

Dim request As System.Net.HttpWebRequest = System.Net.HttpWebRequest.Create("direct link to my online txt file")
Dim response As System.Net.HttpWebResponse = request.GetResponse

Dim sr As System.IO.StreamReader = New System.IO.StreamReader(response.GetResponseStream)

Dim stringReader As String

        stringReader = sr.ReadLine()
        Button10.Text = stringReader


        Dim newestversion As String = sr.ReadToEnd
        Dim currentversion As String = Application.ProductVersion

        Dim part() As String = Split(newestversion, vbCrLf)

        If part.Length < 10 Then
            ' not enough items in the array. You could also throw and exception or do some other stuff here
            Label10.Text = "beta"
            Exit Sub
        End If


        'updates new episode numbers on buttons
        Button20.Text = part(0)
        Button30.Text = part(1)
        Button40.Text = part(2)
        Button50.Text = part(3)
        Button60.Text = part(4)
        Button70.Text = part(5)
        Button80.Text = part(6)
        Button90.Text = part(7)
        Button100.Text = part(8)
        Button110.Text = part(9)

    End If

谢谢！！

Answer 1

您将String 拆分为line breaks。这为您提供了一个数组，String 中的每一行都有一个条目。但是，您不会检查此数组是否包含您期望的项目数量。你可以这样做：

Dim newestversion As String = sr.ReadToEnd
Dim currentversion As String = Application.ProductVersion

Dim part() As String = Split(newestversion, vbCrLf)

If part.Length < 10 Then
    ' not enough items in the array. You could also throw and exception or do some other stuff here
    MsgBox(String.Format("Array only has {0} items", part.Length))
    Exit Sub 
End If

'updates new episode numbers on buttons
Button20.Text = part(0)
Button30.Text = part(1)
Button40.Text = part(2)
...

编辑更新的问题

如果您确实遇到这样的问题，只需系统地处理它并尽可能多地获取信息。首先，您必须检查您是否真的从远程源获得了您想要的数据。为此，请添加一些日志记录（例如 MsgBox(newestversion) 或真实日志文件）。 检查您获得的数据是否符合您的预期。如果不是，那么您的请求/响应代码已经存在问题，这与我提供的解决方案完全不同。如果newestversion 正常，则通过打印出part() 数组来检查拆分是否有效。也许服务器使用不同的操作系统，或者只是使用vbCr 作为换行符而不是vbCrlf。如果拆分也有效，那么您就完成了。