Binding List<string> property to Listbox WPF - wpf

Question

Can someone help me? I have the folowing XAML code in my MainWindow.xaml file:
<ListBox ItemsSource="{Binding Files}" HorizontalAlignment="Left"
Height="371" Margin="281,53,0,0" VerticalAlignment="Top"
Width="609">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
And in my ViewModel.cs I have property:
public List<string> Files { get; set; }
But, when I click the button and add some items to Files nothing happens.
P.S. Sorry for my bad English :)

Answer 1

List does not implement INotifyCollectionChanged, instead of List, use ObservableCollection<string>
Additional Info: List vs ObservableCollection vs INotifyPropertyChanged

Answer 2

Here is your solution, just add this code and press 'Add String' button to make it work. I have used 'ObservableCollection' instead of List and made to listen it using 'INotifyPropertyChanged' interface in ViewModel.cs class
MainWindow.xaml
<Window x:Class="ListBox_Strings.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:myApp="clr-namespace:ListBox_Strings"
Title="MainWindow" Height="350" Width="525">
<Window.DataContext>
<myApp:ViewModel/>
</Window.DataContext>
<Grid>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition Height="50"/>
</Grid.RowDefinitions>
<ListBox ItemsSource="{Binding Files}" HorizontalAlignment="Left"
VerticalAlignment="Top" >
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<Button Grid.Row="1" Content="Add String" Click="Button_Click"></Button>
</Grid>
</Window>
MainWindow.xaml.cs
using System.Windows;
namespace ListBox_Strings
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
var vm = this.DataContext as ViewModel;
vm.Files.Add("New String");
}
}
}
ViewModel.cs
using System.Collections.ObjectModel;
using System.ComponentModel;
namespace ListBox_Strings
{
public class ViewModel:INotifyPropertyChanged
{
private ObservableCollection<string> m_Files;
public ObservableCollection<string> Files
{
get { return m_Files; }
set { m_Files = value;
OnPropertyChanged("Files"); }
}
public ViewModel()
{
Files = new ObservableCollection<string>();
Files.Add("A");
Files.Add("B");
Files.Add("C");
}
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string name)
{
if (PropertyChanged != null)
{
this.PropertyChanged(this, new PropertyChangedEventArgs(name));
}
}
}
}