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c#winformsasynchronousasync-awaitlistbox
Hassan Le algerino
Hassan Le algerino

Reputation: 13

How to update a listbox asyncronously c#?

Hi I am trying to update my listbox asyncronously, so it wouldnt freeze for one sec while updating, unfortunately it throws an exception

My code

private async void timer1_Tick(object sender, EventArgs e) {
      

            await Task.Run(() =>
            {
                listBox1.DataSource = listboxitems;
                listBox1.TopIndex = listBox1.Items.Count - 1;
            });
            
}

Exception

System.Reflection.TargetInvocationException: 

InvalidOperationException: Invalid cross-thread operation: the listBox1 control was accessed by a different thread 
than the thread for which it was created.

Anyone got a clue, how can I fix this ?

Upvotes: 0

Views: 301

Answers (1)

Emanuele
Emanuele

Reputation: 888

Cross thread is when you try to invoke from another thread (in your case the Task one) a method of the main thread (in your case the UI one).

You can ask, from the secondary thread, that UI thread do the work like this:

listBox1.Dispatcher.Invoke(() => {
  listBox1.DataSource = listboxitems; 
  listBox1.TopIndex = listBox1.Items.Count - 1;
});

Upvotes: 3

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