Question

我尝试使用VB.NET创建一个小程序。

打开时，会在网页下方显示网页和进度条。当用户单击网页中的链接时，progess栏将停止处理并显示You clicked a link消息。处理完成后，会显示另一条消息：Thanks for helping me。

我在VB.NET中编写了整个过程的代码，但是当我调试它时会显示一条消息：

'0'的值对'index'无效。 'index'应介于0和-1之间。参数名称：index

我的代码是：

 Public Class MyPage
    Private Sub MyPage_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Timer1.Interval = 1500
    End Sub

    Private Sub WebBrowser1_DocumentCompleted(ByVal sender As System.Object, ByVal e As System.Windows.Forms.WebBrowserDocumentCompletedEventArgs) Handles WebBrowser1.DocumentCompleted
        WebBrowser1.Document.Links(0).AttachEventHandler("onclick", AddressOf LinkClick)
    End Sub

    Sub LinkClick(ByVal sender As Object, ByVal e As System.EventArgs)
        Timer1.Start()
        MsgBox("You clicked the link", , "Clicked The link")
    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        ProgressBar1.Increment(2)
        If ProgressBar1.Value = 100 Then
            Timer1.Stop()
            ProgressBar1.Value = 0
            MsgBox("Thanks for help me", , "Thankssss!")
        End If
    End Sub
 End Class

我该如何解决这个问题？

Answer 1

你盲目地假设页面总是有一个链接。错误的假设。修正：

Private Sub WebBrowser1_DocumentCompleted(ByVal sender As System.Object, ByVal e As System.Windows.Forms.WebBrowserDocumentCompletedEventArgs) Handles WebBrowser1.DocumentCompleted
    If WebBrowser1.Document.Links.Count > 0 Then
        WebBrowser1.Document.Links(0).AttachEventHandler("onclick", AddressOf LinkClick)
    End If
End Sub

或者根据用途，更明白：

    For Each link As HtmlElement In WebBrowser1.Document.Links
        link.AttachEventHandler("onclick", AddressOf LinkClick)
    Next

VB.NET浏览器单击事件处理程序：值“0”对“索引”错误无效

1 个答案: