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How to: Create and Bind to an ObservableCollection

This example shows how to create and bind to a collection that derives from the ObservableCollection(Of T) class, which is a collection class that provides notifications when items get added or removed.

The following example shows the implementation of a NameList collection:

Public Class NameList
    Inherits ObservableCollection(Of PersonName)

    ' Methods 
    Public Sub New()
        MyBase.Add(New PersonName("Willa", "Cather"))
        MyBase.Add(New PersonName("Isak", "Dinesen"))
        MyBase.Add(New PersonName("Victor", "Hugo"))
        MyBase.Add(New PersonName("Jules", "Verne"))
    End Sub 

End Class 

Public Class PersonName
    ' Methods 
    Public Sub New(ByVal first As String, ByVal last As String)
        Me._firstName = first
        Me._lastName = last
    End Sub 


    ' Properties 
    Public Property FirstName() As String 
        Get 
            Return Me._firstName
        End Get 
        Set(ByVal value As String)
            Me._firstName = value
        End Set 
    End Property 

    Public Property LastName() As String 
        Get 
            Return Me._lastName
        End Get 
        Set(ByVal value As String)
            Me._lastName = value
        End Set 
    End Property 


    ' Fields 
    Private _firstName As String 
    Private _lastName As String 
End Class

You can make the collection available for binding the same way you would with other common language runtime (CLR) objects, as described in How to: Make Data Available for Binding in XAML. For example, you can instantiate the collection in XAML and specify the collection as a resource, as shown here:


<Window
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  xmlns:c="clr-namespace:SDKSample"
  x:Class="SDKSample.Window1"
  Width="400"
  Height="280"
  Title="MultiBinding Sample">
	
  <Window.Resources>
    <c:NameList x:Key="NameListData"/>


...


</Window.Resources>

You can then bind to the collection:

<ListBox Width="200"
         ItemsSource="{Binding Source={StaticResource NameListData}}"
         ItemTemplate="{StaticResource NameItemTemplate}"
         IsSynchronizedWithCurrentItem="True"/>

The definition of NameItemTemplate is not shown here.

Note Note

The objects in your collection must satisfy the requirements described in the Binding Sources Overview. In particular, if you are using OneWay or TwoWay (for example, you want your UI to update when the source properties change dynamically), you must implement a suitable property changed notification mechanism such as the INotifyPropertyChanged interface.

For more information, see the Binding to Collections section in the Data Binding Overview.

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