CODEWITHSUNDEEP
vb.netloops
cnbandicoot
cnbandicoot

Reputation: 370

vb.net - Stop loop when I press Button

I have a loop (in another class) what I want stop when I press a button, but I don't know how to do it

This is my code:

'My FORM

Dim blStop = False

Private Sub btnFilter_Click(sender As Object, e As EventArgs) Handles btnFilter.Click
        AnotherClass.doTheLoop(blStop)
End Sub

Private Sub btnStop_Click(sender As Object, e As EventArgs) Handles btnStop.Click
        blStop = True
End Sub



'AnotherClass Loop

While (blStop = False)
    'blablabla
End While

Upvotes: 1

Views: 1287

Answers (2)

Martin Verjans
Martin Verjans

Reputation: 4796

Here is how your other class should look like :

Public class AnotherClass
    Private Shared blStop As Boolean = False

    'blablabla

    Public Shared Sub doTheLoop()
        While Not blStop
            'blablabla
        End While
    End Sub

    Public Shared Sub StopTheLoop()
        blStop = True
    End Sub

    'blablabla
End Class

Then you can call this loop like this :

'Form class
Private Sub btnFilter_Click(sender As Object, e As EventArgs) Handles btnFilter.Click
    'You must run the loop on another thread or you will block the UI thread. 
    'Therefore your application will 'Stop Responding'
    System.Threading.Thread.QueueWorkUserItem(AddressOf(AnotherClass.DoTheLoop))
End Sub

Private Sub btnStop_Click(sender As Object, e As EventArgs) Handles btnStop.Click
    AnotherClass.StopTheLoop()
End Sub

Upvotes: 1

Matt Wilko
Matt Wilko

Reputation: 27322

your issue is this:

Public Sub doTheLoop(blStop as Boolean) 
    While (blStop = False) 
       'blablabla 
    End While 
End Sub

The declaration of blStop, creates a new variable, so when you set, the value to False, you only set the one decalred locally.

A quick and dirty fix would be to declare the boolean ByRef - that would mean that it will still reference the original variable.

Public Sub doTheLoop(ByRef blStop as Boolean) 
    While (blStop = False) 
       'blablabla 
    End While 
End Sub

A better solution would be to have a method in your class that you call when you want to stop rather than passing round variables.

Upvotes: 1

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