Cross-thread operation not valid

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Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on

Okay, I know why this is giving me this error:

Cross-thread operation not valid: Control 'Form1' accessed from a thread other than the thread it was created on.

But... How can I make this workable?

System.Threading.Thread t = new System.Threading.Thread(()=>
{
   // do really hard work and then...
   listView1.Items.Add(lots of items);
   lots more UI work
});
t.Start();

I don't care when, or how the Thread finishes, so I don't really care about anything fancy or over complicated atm, unless it'll make things much easier when working with the UI in a new Thread.

Solution 1

You can't. UI operations must be performed on the owning thread. Period.

What you could do, is create all those items on a child thread, then call Control.Invoke and do your databinding there.

Or use a BackgroundWorker

    BackgroundWorker bw = new BackgroundWorker();
    bw.DoWork += (s, e) => { /* create items */ };
    bw.RunWorkerCompleted += (s, e) => { /* databind UI element*/ };

    bw.RunWorkerAsync();

Solution 2

When you access the from's property from another thread, this exception is thrown. To work around this problem there's at least 2 options.

1. Telling Control to don't throw these exceptions (which is not recommended):

   Control.CheckForIllegalCrossThreadCalls = false;

2. Using threadsafe functions:

   private void ThreadSafeFunction(int intVal, bool boolVal)
   {
       if (this.InvokeRequired)
       {
           this.Invoke(
               new MethodInvoker(
               delegate() { ThreadSafeFunction(intVal, boolVal); }));
       }
       else
       {
           //use intval and boolval
       }
   }