Question

I have a listbox with several items . And the selection changed event has been mapped to a function. But everytime i select a listbox item, event is getting triggered twice. As result i am getting the selected index as -1 on the second round .

anyone knows the reason for this behaviour?

XAML code

<ListBox ItemTemplate="{StaticResource productTemplate}" Name="lstItems" SelectionChanged="ShowProductDetails">

C# code

private void ShowProductDetails(object sender, SelectionChangedEventArgs e)
{
    Item item = lstItems.SelectedItem as Item;
    int index = lstItems.SelectedIndex;
}

Answer 1

A selection changed event happens everytime the selection is changed (either from user input or not)

When you reload the listbox the selection changes (most likely to -1)

this code below checks to ensure that a user has selected something (an item with a valid index i.e. Not -1) then runs the code.

    private void ShowProductDetails(object sender, SelectionChangedEventArgs e)
    {
        if(lstItems.SelectedIndex != -1)
        {
            Item item = lstItems.SelectedItem as Item;
            int index = lstItems.SelectedIndex;
        }
    }