How can I implement incremental search on a listbox?

Question

I want to implement incremental search on a list of key-value pairs, bound to a Listbox.

If I had three values (AAB, AAC, AAD), then a user should be able to select

Answer 1

I realize this is extremely late... however, having just implemented this, I'll leave it here in the hope that it will help someone.

Add a handler to the KeyChar event (the listbox is named lbxFieldNames in my case):

private void lbxFieldNames_KeyPress(object sender, KeyPressEventArgs e)
{
  IncrementalSearch(e.KeyChar);
  e.Handled = true;
}

(Important: you need e.Handled = true; because the listbox implements a "go to the first item starting with this char" search by default; it took me a while to figure out why my code was not working.)

The IncrementalSearch method is:

private void IncrementalSearch(char ch)
{
  if (DateTime.Now - lastKeyPressTime > new TimeSpan(0, 0, 1))
    searchString = ch.ToString();
  else
    searchString += ch;
  lastKeyPressTime = DateTime.Now;

  var item = lbxFieldNames
    .Items
    .Cast()
    .Where(it => it.StartsWith(searchString, true, CultureInfo.InvariantCulture))
    .FirstOrDefault();
  if (item == null)
    return;

  var index = lbxFieldNames.Items.IndexOf(item);
  if (index < 0)
    return;

  lbxFieldNames.SelectedIndex = index;
}

The timeout I implemented is one second, but you can change it by modifying the TimeSpan in the if statement.

Finally, you will need to declare

private string searchString;
private DateTime lastKeyPressTime;

Hope this helps.