VB.NET从列表框中选择链接，然后在Webbrowser控件中浏览到该链接

Question

I have a list of links stored in a listbox. I want a timer control to load one link after the other every 4 seconds, and once it's reached the end of the list, I want the timer to stop. I've tried to achieve this with the code below and it's only loading the first link. Can someone point out my mistake(s)? Thanks in advance!

Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick

    Dim counter As Integer = counter + 1
    If counter > ListBox2.Items.Count Then
        counter = 0
        Timer1.Enabled = False
    Else
        Dim i As Integer
        For i = 0 To ListBox2.Items.Count - 1
            WebBrowser1.Navigate(ListBox2.Items(i))
        Next
    End If

End Sub

Answer 1

You need to declare your counter variable at the class level instead of within your Tick handler, or else its value is always reinitialized to 1.

So in other word, defined it oustide the handler.

Also, you must not loop the entire content of the ListBox within your tick handler.

Here's a better version:

Public Class Form1

    Private counter As Integer = 0

    ...

    Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick

        If counter > ListBox2.Items.Count - 1  Then
            counter = 0
            Timer1.Enabled = False
        Else
             WebBrowser1.Navigate(ListBox2.Items(counter))
        End If
        'Increment at the end to get element(0)
        counter = counter + 1

    End Sub
End Class

Cheers