Question

I have a listbox control on winform and same is Single Items SelectionMode OR One Items Selection Mode. I am trying to scroll it from form_KeyDown Event as below

if ((Keys)e.KeyCode == Keys.Down)
{
     if (listBox2.Items.Count >= listBox2.SelectedIndex) 
     {
           listBox2.SelectedIndex++;

     }

 }

But it’s throw an error like “ArgumentOutOfRangeException was unhandled”
Invalid argument of value =23 is not valid for selection index.

How to get ridoff?

Answer 1

Try this:

if ((Keys)e.KeyCode == Keys.Down)
{
     if ((listBox2.Items.Count-1) > listBox2.SelectedIndex) 
     {
           listBox2.SelectedIndex++;

     }

 }

Remember that if you have 23 items, SelectedIndex goes from 0 to 22…