Hi,
I have a form with a timer.. I also have a listbox that I'm trieng to access it from the elapsed event handler:
private void OnTimedEvent(object source, ElapsedEventArgs e)
{
aTimer.Stop();
//Console.Clear();
//Console.WriteLine("The Elapsed event was raised at {0}", e.SignalTime);
this.listMessages.Items.Add("The Elapsed event was raised at " + e.SignalTime);

(Note: I disabled the "static" for the method cause I can't use the reserved keyword "this" inside it!)

But I'm getting this exception:
An exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll but was not handled in user code Additional information: Cross-thread operation not valid: Control 'listMessages' accessed from a thread other than the thread it was created on.

What is that about?!
Thanks in advance.

Use a System.Windows.Forms timer or Invoke.

Hello,
You need to post more of your code for a more exact answer. Your message says that you have performed an illegal cross-thread operation. You should access form controls only on the main thread---the thread where they were created. Accessing form controls from threads or backgroundworkers will almost always result in that cross-thread exception.

HINT: Accessing only the objects that you define wiithin the thread's scope is the best way to avoid this exception. Pass objects to the thread when you invoke it, and use the APM Callback pattern to return objects from the thread. The BackgroundWorker object has mechanisms and events already defined that seem to do a pretty solid and stable job of passing data to and from threads.


Rudedog =8^D

---

Mark the best replies as answers. "Fooling computers since 1971."

Hi,

According to your code, I suggest you to use System.Windows.Form.Timer control.

http://msdn.microsoft.com/en-us/library/system.windows.forms.timer.aspx

private void Form1_Load(object sender, EventArgs e)

{

timer1.Interval = 5000;

timer1.Start();

timer1.Tick +=new EventHandler(timer1_Tick);

}

private void timer1_Tick(object sender, EventArgs e)

{

this.listBox1.Items.Add(System.DateTime.Now);

}

System.Timers.Timer component is designerd for use with worker threads in a multithreader environment.

http://msdn.microsoft.com/en-us/library/system.timers.timer.aspx

Best regards,

Ling Wang

---

Please remember to click “Mark as Answer�on the post that helps you, and to click “Unmark as Answer�if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Use a System.Windows.Forms timer or Invoke.

Hello,
You need to post more of your code for a more exact answer. Your message says that you have performed an illegal cross-thread operation. You should access form controls only on the main thread---the thread where they were created. Accessing form controls from threads or backgroundworkers will almost always result in that cross-thread exception.

HINT: Accessing only the objects that you define wiithin the thread's scope is the best way to avoid this exception. Pass objects to the thread when you invoke it, and use the APM Callback pattern to return objects from the thread. The BackgroundWorker object has mechanisms and events already defined that seem to do a pretty solid and stable job of passing data to and from threads.


Rudedog =8^D

---

Mark the best replies as answers. "Fooling computers since 1971."

Hi,

According to your code, I suggest you to use System.Windows.Form.Timer control.

http://msdn.microsoft.com/en-us/library/system.windows.forms.timer.aspx

private void Form1_Load(object sender, EventArgs e)

{

timer1.Interval = 5000;

timer1.Start();

timer1.Tick +=new EventHandler(timer1_Tick);

}

private void timer1_Tick(object sender, EventArgs e)

{

this.listBox1.Items.Add(System.DateTime.Now);

}

System.Timers.Timer component is designerd for use with worker threads in a multithreader environment.

http://msdn.microsoft.com/en-us/library/system.timers.timer.aspx

Best regards,

Ling Wang

---

Please remember to click “Mark as Answer�on the post that helps you, and to click “Unmark as Answer�if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

I already did it, thank you anyway :)