How can I programmatically select an item in a listbox?

Question

I have a listbox displaying items from an enum. I want to select/highlight the current value (read from a database) when the listbox displays/the form opens. This code, though:

lblSelectedPrinter.Text = AppSettings.ReadSettingsVal("beltprinter");
listBoxBeltPrinters.SelectedItem = listBoxBeltPrinters.Items.IndexOf(lblSelectedPrinter.Text);

...does not work. I saw an example using "GetItemAt" here (Programmatically selecting Items/Indexes in a ListBox) but my stripped down and archaic version of C# (.NET 1.1, C# 2) has no such critter.

UPDATE

I thought this would work:

string currentPrinter = AppSettings.ReadSettingsVal("beltprinter");
lblSelectedPrinter.Text = currentPrinter;
int currentPrinterIndex = listBoxBeltPrinters.Items.IndexOf(currentPrinter);
listBoxBeltPrinters.SelectedItem = currentPrinterIndex;

...but it, also, does not (the current printer displays in the label, but the corresponding entry/value in the listbox is not selected).

Answer 1

I see you've already solved this, but why not do it the tried and tested way?

  lblSelectedPrinter.Text = AppSettings.ReadSettingsVal("beltprinter");
  listBoxBeltPrinters.SelectedIndex = -1;
  if (!String.IsNullOrEmpty(lblSelectedPrinter.Text)) {
    for (int index = 0; index < listBoxBeltPrinters.Items.Count; index++) {
      string item = listBoxBeltPrinters.Items[index].ToString();
      if (lblSelectedPrinter.Text == item) {
        listBoxBeltPrinters.SelectedItem = index;
        break;
      }
    }
  }

This way, you know the SelectedIndex value is set to -1 as soon as the text changes, and if it is found in your ListBox, that item is selected.

Even better would be to write a handler when the Label control lblSelectedPrinter fires the TextChanged event.

lblSelectedPrinter.TextChanged += new EventHandler(SelectedPrinter_TextChanged);

Then, create that Event Handler like shown above:

private void SelectedPrinter_TextChanged(object sender, EventArgs e) {
  listBoxBeltPrinters.SelectedIndex = -1;
  if (!String.IsNullOrEmpty(lblSelectedPrinter.Text)) {
    for (int index = 0; index < listBoxBeltPrinters.Items.Count; index++) {
      string item = listBoxBeltPrinters.Items[index].ToString();
      if (lblSelectedPrinter.Text == item) {
        listBoxBeltPrinters.SelectedItem = index;
        break;
      }
    }
  }
}

You've already solved your problem, so this is just food for thought.

Answer 2

This works:

listBoxBeltPrinters.SetSelected(listBoxBeltPrinters.FindString("beltprinter"), true);