ReportProgress in BackgroundWorker - vb.net

Question

The progress bar is repeated two or three times before completing the operation on my backgroundworker
this code:
Private Sub BackgroundWorker1_DoWork(sender As System.Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
'Load Data
For i As Integer = 0 To ListData.Count
BackgroundWorker1.ReportProgress((i / ListData.Count) * 100)
Next
If BackgroundWorker1.CancellationPending Then
e.Cancel = True
End If
End Sub
Private Sub BackgroundWorker1_ProgressChanged(sender As System.Object, e As System.ComponentModel.ProgressChangedEventArgs) Handles BackgroundWorker1.ProgressChanged
Me.ProgressBar1.Value = e.ProgressPercentage
End Sub
Private Sub BackgroundWorker1_RunWorkerCompleted(sender As System.Object, e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted
'set datasource of DatagridView
ProgressBar1.Style = ProgressBarStyle.Blocks
End Sub
In my load form
BackgroundWorker1.WorkerReportsProgress = True
BackgroundWorker1.WorkerSupportsCancellation = True
BackgroundWorker1.RunWorkerAsync()
ProgressBar1.Style = ProgressBarStyle.Marquee
please help me

Answer 1

You have several mistakes. First, if you intend to display an increasing progress bar, you should use:
ProgressBar1.Style = ProgressBarStyle.Continuous
in your load form. Next, you are checking BackgroundWorker1.CancellationPending only after going through all your ListData. That is too late, you have to check it every iteration of the loop. I also really doubt you want your loop to go from 0 to ListData.Count; you probably either want to start at 1 or go to ListData.Count - 1. I can't tell from your question. Your loop should look more like this:
For i as Integer = 0 To ListData.Count - 1
If BackgroundWorker1.CancellationPending Then
e.Cancel = True
Exit For
Else
' You should be doing some work here, not just calling ReportProgress
BackgroundWorker1.ReportProgress(100 * (i+1) / ListData.Count)
End If
Next
Another mistake is calculating (i / ListData.Count) * 100; i and ListData.Count are integers, so their division will always be zero until the end, when it will be 1. Instead, multiply the numerator by 100 to get percentages.