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Cross Thread

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23 Oct 2006CPOL 55.2K   950   25   6
We can't perform operations on a control, if that control was created by another thread. When we try to do thatm, we will get cross thread exceptions.

Sample Image - Cross_Thread.jpg


We can't perform operation on a control, if that control was created by another thread. While doing this kind of operations, we get Cross Thread is not valid. like that.

About this code

In this sample, i have used only one text box. I am planning to display GUID in textbox with uncondition loop. If we do that without thread, the application will be hang. so, I have created a thread in form load event.
private void Form1_Load(object sender, EventArgs e)
       guidThread = new Thread(new ThreadStart(CreateNewGuid));

Thread Method

There is a method CreateNewGuid() to generate guid with unconditional loop. Here, invoking a delegate event GuidThreadCallBack() to assgin the new generated guid to text box.
public delegate void GuidThreadCallBack();
while (true)
    newGUID = Guid.NewGuid().ToString();
     this.Invoke(new GuidThreadCallBack(setTextBoxValue));
    catch { guidThread.Abort(); }

Delegate Event Method

This method will assign the value to the text box. While assging the value to textbox, the delegate event method will use which thread created the text box.
private void setTextBoxValue()
   textBox1.Text = newGUID;


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Written By
Software Developer General Physics Corporation (GP)
India India
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Comments and Discussions

GeneralWatiN problem on Vista Pin
Kvita Patil30-Jul-09 2:11
Kvita Patil30-Jul-09 2:11 
GeneralGot cross thread operation exception Pin
Kvita Patil4-Jul-09 0:55
Kvita Patil4-Jul-09 0:55 
QuestionProblem in ASP.NET Pin
Om Rudi12-Aug-08 18:01
Om Rudi12-Aug-08 18:01 
Generalanother way ... Pin
Antofagasta20-Jun-08 9:09
Antofagasta20-Jun-08 9:09 
GeneralCross Thread not valid in Form Pin
anu91417-Mar-08 19:24
anu91417-Mar-08 19:24 
When i try to access a picture box in a form using another thread, I get an exception saying " Cross Thread Operation not valid in Form".

Please help me if anybody have an idea how to solve this.

Any help would be really appreciated.

Thank you
Questionwhat about BackgroundWorker? Pin
eligazit24-Oct-06 13:03
eligazit24-Oct-06 13:03 

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