WPF

Line previousLine = null;
foreach (UIElement child in TargetCanvas.Children )
{
    if( child is Line)
    {
        previousLine = child as Line;
        break;
    }
}

if (null != previousLine)
{
    TargetCanvas.Children.Remove(previousLine);
}

psdeepu wrote:

Please help thanks

class A : INotifyPropertyChanged
{
    List<string> _list;
    public List<string> List
    {
        get
        {
            return _list;
        }
        set
        {
            _list = value;
            NotifyPropertyChanged("List");
        }
    }

    private void NotifyPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

<Window x:Class="WpfApplication1.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="300" Width="300">
    <StackPanel>
        <ListBox ItemsSource="{Binding List}" />
        <Button Click="Button_Click" Content="Change reference" />
    </StackPanel>
</Window>

public partial class Window1 : Window
{
    A _a;

    public Window1()
    {
        InitializeComponent();

        _a = new A();
        _a.List = new List<string>
        {
            "a",
            "b",
            "c",
            "d",
            "e",
        };
        this.DataContext = _a;
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        _a.List = new List<string>()
        {
            "0",
            "1",
            "2",
            "3",
            "4",
            "5",
            "6",
            "7",
            "8",
            "9",
        };
    }
}

mylistbox.ItemsSource = _a.List;