crossthread operations error

Question

      if (listBox1.InvokeRequired)
       {
           listBox = new StringBuilder(this.listBox1.Text);
       }

This is the code in c# which when exec

Answer 1

Your code should run when InvokeRequired is false

delegate void SetListBoxDelegate(); 

void SetListBox()
{
    if(!InvokeRequired)
    {
        listBox = new StringBuilder(this.listBox1.Text);
    } 
    else 
        Invoke(new SetListBoxDelegate(SetListBox)); 
} 

Edit: Check out Making Windows Forms thread safe