Cross Thread

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Introduction

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));
       guidThread.Start();
}

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();
    try
    {
     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;
   textBox1.Refresh();
 }