#982 – Executing Code When Selected Items in a ListBox Change

You can handle the SelectionChanged event for a ListBox to react to a change in the currently selected items.

Within the event handler, you can inspect the following properties of the SelectionChangedEventArgs parameter:

• AddedItems – Collection of items just selected, type matches type of object in collection that ListBox is bound to
• AddedInfos – Can get index and ListBoxItem for added items
• RemovedItems – Collection of items just unselected
• RemovedInfos – Get index and ListBoxItem for removed items

        <ListBox Name="lbActors" Margin="15" Width="200" Height="190"
                 ItemsSource="{Binding ActorList}"
                 SelectionMode="Extended"
                 SelectionChanged="lbActors_SelectionChanged"/>
        <TextBlock Name="tbInfo"/>

        private void lbActors_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            StringBuilder sbInfo = new StringBuilder();

            sbInfo.AppendLine("Added:");
            foreach (object o in e.AddedItems)
            {
                Actor a = o as Actor;
                sbInfo.AppendLine(a.FullName);
            }

            sbInfo.AppendLine("Removed:");
            foreach (object o in e.RemovedItems)
            {
                Actor a = o as Actor;
                sbInfo.AppendLine(a.FullName);
            }

            tbInfo.Text = sbInfo.ToString();
        }