Programmatically selecting Items/Indexes in a List

Question

In WPF, I'd like to set the selected indexes of a System.Windows.Controls.ListBox

I best way I've found so far is to remove all the items from the control, insert the selected, call SelectAll(), then insert the rest, but this solution neither works in my situation nor is very efficient.

So, how do you set items in a Listbox to be selected, programmatically?

Answer 1

You have to do this:

ListBoxObject.SelectedItem = ListBoxObject.Items.GetItemAt(itemIndex);

Where itemIndex would be the item you want to select. If you want to select multiple items, you need to use the ListBox.SelectedIndexCollection property.

Answer 2

You can do this for multiple sections:

ListBoxObject.SelectedItems.Add(ListBoxObject.Items.GetItemAt(i));

Where i is the item index.

Answer 3

how to programmatically select multiple items in listbox in wpf

foreach (var boundObject in objectsBoundToListBox)
{
    ListBox.SelectedItems.Add(boundObject);
}

Answer 4

One way you can do this is to add a Selected field to your data object. Then you need to overide the default listboxitem style and bind the isselected property to the Selected property in your object. Then you just need to go through your data items and update the Selected value.

If you don't implement that Selected property as a dependency property, you need your class to implented the INotifyPropertyChanged interface and raise the propertychanged event when you set the value.

Answer 5

You can set multiple items as selected by using the SelectedItems collection. This isn't by index, but by what you have bound:

foreach (var boundObject in objectsBoundToListBox)
{
    ListBox.SelectedItems.Add(boundObject);
}

Answer 6

Thanks to mdm20. My case was actually checking a CheckBox within the ListBox, and this Dependency Property worked like a charm. I had to inherit my custom class from DependencyObject and implement the property

public class ProjectListItem : DependencyObject{ 

    public Boolean IsChecked
    {
        get { return (Boolean)this.GetValue(CheckedProperty); }
        set { this.SetValue(CheckedProperty, value); }
    }
    public static readonly DependencyProperty CheckedProperty =
        DependencyProperty.Register("IsChecked", typeof(Boolean), typeof(ProjectListItem), 
                                    new PropertyMetadata(false));
}