WPF Interview Questions ,When the SelectionChanged event gets raised, how do I get the new selection?

The SelectionChanged event is designed to handle controls that allow multiple selections,

so it can be a little confusing for a single-selection selector such as ComboBox. The

SelectionChangedEventArgs type passed to event handlers has two properties of type

IList: AddedItems and RemovedItems. AddedItems contains the new selection and

RemovedItems contains the previous selection.

e.g.

void ComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)

{

if (e.AddedItems.Count > 0)

object newSelection = e.AddedItems[0];

}

Like this code, never assume that there’s a selected item! Besides the fact that ComboBox’s

selection can be cleared programmatically, it can get cleared by the user when IsEditable is

true and IsReadOnly is false. In this case, if the user changes the selection box text to

something that doesn’t match any item, the SelectionChanged event is raised with an

empty AddedItems collection.