Which CheckedListBox event triggers after a item is checked?

Question

I have a CheckedListBox where I want an event after an item is checked so that I can use CheckedItems with the new state.

Since ItemChecked is fired before CheckedItems is updated it won't work out of the box.

What kind of method or event can I use to be notified when the CheckedItems is updated?

Answer 1

You have new state of item in e.NewValue, if NewValue is checked add current item to collection:

    private void checkedListBox1_ItemCheck(object sender, ItemCheckEventArgs e)
    {                     
        List<string> checkedItems = new List<string>();
        foreach (var item in checkedListBox1.CheckedItems)
            checkedItems.Add(item.ToString());

        if (e.NewValue == CheckState.Checked)
            checkedItems.Add(checkedListBox1.Items[e.Index].ToString());

        foreach (string item in checkedItems)
        {
            ...
        }
    }

Answer 2

Although not ideal, you can calculate the CheckedItems using the arguments that are passed through to the ItemCheck event. If you look at this example on MSDN, you can work out whether the newly changed item has been checked or unchecked, which leaves you in a suitable position to work with the items.

You could even create a new event that fires after an item is checked, which would give you exactly what you wanted if you wished.