?
Solved

Background worker cancelling from another form

Posted on 2016-09-23
8
Medium Priority
?
34 Views
Last Modified: 2016-10-09
Using vb.net for an application i'm developing.  During a backgroundworker routine, I have a semi-transparent overlay form over top with a progress bar and cancel button.  However when I try to cancel I get the error: Object reference not set to an instance of an object.

How can I cancel a backgroundworker from another form?  This is my code from the second (overlay) form.

Public Class CISMapOverlay
     Private myParent As frmGMapNet

    Private Sub Label2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadLabel2.Click
        Me.myParent.BackgroundWorker1.CancelAsync()
        Me.Hide()
    End Sub

    Public Sub New()

        ' This call is required by the designer.
        InitializeComponent()
        Me.myParent = myParent

        ' Add any initialization after the InitializeComponent() call.

    End Sub
End Class

Open in new window

0
Comment
Question by:K-9
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 2
8 Comments
 
LVL 44

Accepted Solution

by:
AndyAinscow earned 2000 total points
ID: 41812492
You never assign a value to your variable myParent in the code you show.  Once you set that to the 'parent' form you should be able to do what you want (BackgroundWorker1 would need to be a public variable).
0
 

Author Comment

by:K-9
ID: 41812493
Yes I did: Private myParent As frmGMapNet
frmGMapNew is the form where the Backgroundworker is.
0
 

Author Comment

by:K-9
ID: 41812502
Wow.. that's weird.  If I use frmGMapNew.BackgroundWorker1.CancelAsync() it works.  For some reason it doesn't like using myParent
0
Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 44

Expert Comment

by:AndyAinscow
ID: 41812534
Sounds like you have the BackgroundWorker1 as a static variable in that case.
0
 
LVL 44

Expert Comment

by:AndyAinscow
ID: 41812537
ps.  I told you why the myParent doesn't work in my first comment.
0
 
LVL 44

Expert Comment

by:AndyAinscow
ID: 41828034
My first comment points out what is wrong with the code supplied and how to fix it.
#a41812492
0

Featured Post

Get free NFR key for Veeam Availability Suite 9.5

Veeam is happy to provide a free NFR license (1 year, 2 sockets) to all certified IT Pros. The license allows for the non-production use of Veeam Availability Suite v9.5 in your home lab, without any feature limitations. It works for both VMware and Hyper-V environments

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This document covers how to connect to SQL Server and browse its contents.  It is meant for those new to Visual Studio and/or working with Microsoft SQL Server.  It is not a guide to building SQL Server database connections in your code.  This is mo…
Wouldn’t it be nice if you could test whether an element is contained in an array by using a Contains method just like the one available on List objects? Wouldn’t it be good if you could write code like this? (CODE) In .NET 3.5, this is possible…
Monitoring a network: how to monitor network services and why? Michael Kulchisky, MCSE, MCSA, MCP, VTSP, VSP, CCSP outlines the philosophy behind service monitoring and why a handshake validation is critical in network monitoring. Software utilized …
This is my first video review of Microsoft Bookings, I will be doing a part two with a bit more information, but wanted to get this out to you folks.
Suggested Courses

801 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question