how to solve cross thread operation not valid Exception?

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I'm using backgroundworker control in my project, to show the progress bar, and I am getting cross thread exception in backgroundWorker_Dowok event.

Please help.

Here is my code:

C#

private void btnGenerate_Click(object sender, EventArgs e)
       {

           
           toolStripProgressBar1.Style = ProgressBarStyle.Marquee;
           backgroundWorker1.RunWorkerAsync();
       }
       private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
       {
                   
           bool flag;
            try
            {
             
               clientid = convert.ToString(ddlClientName.SelectedValue); 
               clientid = Convert.ToString(ddlprincipalname.SelectedValue); 
               clid = Convert.ToInt32(ddlClientName.SelectedValue);
               prid = Convert.ToInt32(ddlprincipalname.SelectedValue); 

                   flag = check_op_close_stock();
                   if (flag)
                   {
                       excel_header();
                       get_excel_data();
                       
                       get_nostk_transit();
                       set_formating();
                   }
               }
            
               catch (Exception ex)
               {
                   MessageBox.Show(ex.Message.ToString());
               }
           }

Posted 24-Nov-10 21:59pm

savita from Pune

Updated 24-Nov-10 22:48pm

Dalek Dave

v2

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Dalek Dave 25-Nov-10 4:48am

Edited for Readability.

johannesnestler 25-Nov-10 9:49am

What be a lot easier to help you if:
* You provide the code where the exception occurs (where you access your GUI-Components (Controls))
* Tell us, if you understand what the exception tells you!

I think you don't understand, so I recommend: Try to understand the problem - If you debug your code - click on help for that exception and follow the docu! If unsolvable by this learn how to use msdn docu and your programming language. Sorry for this rude answer, but im tired of explaining this issue 1000 times...

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J a a n s · Answer 1 · 2010-11-24T22:04:00

Solution 1

You have to make use of InvokeRequired property and the Invoke()method of a Control class.

Check this[^] article for the details/examples.

Posted 24-Nov-10 22:04pm

J a a n s

Comments

savita from Pune 25-Nov-10 4:07am

I dont Know how to use this InvokeRequired property and method, can u send the code how to use this?

J a a n s 25-Nov-10 4:13am

As a workaround, try to set the Control.CheckForIllegalCrossThreadCalls property as false.

savita from Pune 25-Nov-10 4:16am

I used it in DoWork event before try block, but the error remains

savita from Pune 25-Nov-10 4:39am

If anybody knows the answer, please reply fast, its an urgent

Dalek Dave 25-Nov-10 4:48am

Good Answer.

**JF2015** · Answer 2 · 2010-11-24T23:23:00

Solution 2

There are tons of articles out there. Check out the official msdn documentation:

http://msdn.microsoft.com/en-us/library/ms171728(VS.80).aspx[^]

You did not post the method that updates the progress bar, but the invoke required must be checked in this method.

It should look something like this:

C#

private void setProgress(int nValue)
{
  if(progressBar.InvokeRequired)
    progressBar.Invoke(new my_delegate(setProgress),new object[]{nValue});
  else
  {    
    progressBar.Value = nValue;
  }
}

private delegate void my_delegate(int nValue);

Posted 24-Nov-10 23:23pm

JF2015

v2

Comments

savita from Pune 25-Nov-10 5:50am

Hi,when i click on Generate button, i want to show progress bar, till my data saved in excel sheet, that is till set_formating(); completed
but the error occurred at ddlclientname and ddlprincipalname(both are dropdownlist) that is Cross thread operation not valid

JF2015 25-Nov-10 8:04am

So that makes it clear. Not only your progressbar is the problem, it's the dropdownlists too - of course they throw the same exception when you try to access them from a thread.