Question

I’m using a DO interation to loop a function I’m using to test for internet connectivity. The code is working fine, except that when one of the tests is satisfied the loop stops. I want this to continue in the background while the program is running. How can I get this to work?

Private Sub checkInternet()

    Dim InetChecker As Boolean
    InetChecker = CheckForInternetConnection()
    Do While LabelCount.Text <> ""
        Thread.Sleep(10)
        If InetChecker = True Then
            Dim image = My.Resources.greenbar
            PictureBox4.Image = image

        Else
            Thread.Sleep(10)
            Dim image = My.Resources.redbar
            PictureBox4.Image = image
            'NoInetConnError.Show()
        End If
    Loop
End Sub

Your assistance would be greatly appreciated, thanks.

Answer 1

Put a BackgroundWorker on your form (you will find it in the Components section of the Toolbox).

In the Properties window set WorkerReportsProgress to True for your BackgroundWorker.

Insert the following code to your form

Private connected As Boolean

Private Sub BackgroundWorker1_DoWork(ByVal sender As Object, ByVal e As DoWorkEventArgs) _
 Handles BackgroundWorker1.DoWork
    While True
        Dim online = CheckForInternetConnection()
        If online <> connected Then
            connected = online
            BackgroundWorker1.ReportProgress(CInt(online))
        End If
        Thread.Sleep(500)
    End While
End Sub

Private Sub BackgroundWorker1_ProgressChanged(ByVal sender As Object, ByVal e As ProgressChangedEventArgs) _
 Handles BackgroundWorker1.ProgressChanged
    Dim online As Boolean = CBool(e.ProgressPercentage)
    If online Then
        PictureBox4.Image = My.Resources.greenbar
    Else
        PictureBox4.Image = My.Resources.redbar
    End If
End Sub

Private Sub Form_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) _
 Handles MyBase.Load
    ' Start the background worker
    BackgroundWorker1.RunWorkerAsync()
End Sub

Note that Sub BackgroundWorker1_DoWork runs on a separate thread and does not freeze your form while it is running.