Question

<ListBox x:Name="MainList" HorizontalAlignment="Left" Height="468" Margin="10,10,0,0" VerticalAlignment="Top" Width="100" ItemsSource="{Binding Items,Mode=TwoWay}" DisplayMemberPath="Name"/>



[Serializable()]
public class MYcontainer : INotifyPropertyChanged,ISerializable
{
    private List<MYClass> _items = new List<MYClass>();
    public List<MYClass> Items
    {
        get{ return _items;}
       set { this._items =value;
        OnPropertyChanged("Items");
    }
public event PropertyChangedEventHandler PropertyChanged;
    public void OnPropertyChanged(string propertyName = null)
    {
        var eventHandler = this.PropertyChanged;
        if (eventHandler != null)
            eventHandler(this, new PropertyChangedEventArgs(propertyName));
    }  
}

When I add an item to “Items” the UI doesn’t update, the binding is working fine, since if I closed the window and opened it again, the new items appear correctly.

What am I doing wrong? I know if I used ObservableCollection it will work fine, but shouldn’t it work with List<>? I already have in another window a string[] property and it update fine.

Answer 1

If you don’t want to ues ObservableCollection you will have to implement INotifyCollectionChanged.

public partial class MainWindow : Window, INotifyCollectionChanged
{

    public event NotifyCollectionChangedEventHandler CollectionChanged;

    public MainWindow()
    {
        InitializeComponent();
    }


    public void NotifyCollectionChanged(NotifyCollectionChangedAction action)
    {
        if (CollectionChanged != null)
        {
            CollectionChanged(this, new NotifyCollectionChangedEventArgs(action));
        }
    }
}

However ObservableCollection does all this for you, adding all the same logic to your List<T> would just create a custom ObservableCollection, I see no point in this when MS has alraedy made this for you