BackgroundWorker Class

Posted on 2013-12-19
Medium Priority
Last Modified: 2013-12-20
Can anyone show me an example of how to use the BackgroundWorker Class in the following scenario?

I'm calling a sub statement that looks something like this:

Sub DoSomething()
       For a as integer = 1 to 10

          ' Update 'a' on the screen
End Sub

When DoSomething is called I want to display 'a' on the screen.  I also want to show the status of DoSomeThingElseA and DoSomeThingElseB

I don't want the For Next Loop to advance until DoSomeThingElseA and DoSomeThingElseB
have completed there tasks.
Question by:Ray Turner
LVL 25

Accepted Solution

Luis Pérez earned 1000 total points
ID: 39731258
Please, follow these steps:

1. Place a BackgroundWorker component inside your Form.
2. Set the WorkerReportsProgress property of the BackgroundWorker to True.
3. Double-click on the BackgroundWorker to open it's code screen and write this code into the BackgroundWorker1_DoWork event handler:

Private Sub BackgroundWorker1_DoWork(sender As System.Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
    For a As Integer = 1 To 10
        BackgroundWorker1.ReportProgress(0, "After DoSomeThingElseA")
        BackgroundWorker1.ReportProgress(0, "After DoSomeThingElseB")
End Sub

Open in new window

Now write this code into the BackgroundWorker1_ProgressChanged event handler:

Private Sub BackgroundWorker1_ProgressChanged(sender As Object, e As System.ComponentModel.ProgressChangedEventArgs) Handles BackgroundWorker1.ProgressChanged
    Select Case DirectCast(e.UserState, String)
        Case "After DoSomeThingElseA"
            'Write your code here
        Case "After DoSomeThingElseB"
            'Write your code here
    End Select
End Sub

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If you want to control when the BackgroundWorker finishes his work, then write this code into the BackgroundWorker1_RunWorkerCompleted event handler:

Private Sub BackgroundWorker1_RunWorkerCompleted(sender As Object, e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted
    'The work has finished
End Sub

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Finally, from somewhere in your Form, start the BackgroundWorker's job:

Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
End Sub

Open in new window

Hope that helps.
LVL 71

Assisted Solution

by:Éric Moreau
Éric Moreau earned 1000 total points
ID: 39731462

Author Closing Comment

by:Ray Turner
ID: 39731545
Thanks!  This is very helpful!

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