BindingList(T) Class
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BindingList(Of T) Class

Provides a generic collection that supports data binding.

Namespace:  System.ComponentModel
Assembly:  System (in System.dll)

'Declaration
<SerializableAttribute> _
<HostProtectionAttribute(SecurityAction.LinkDemand, SharedState := True)> _
Public Class BindingList(Of T) _
	Inherits Collection(Of T) _
	Implements IBindingList, IList, ICollection, IEnumerable,  _
	ICancelAddNew, IRaiseItemChangedEvents
'Usage
Dim instance As BindingList(Of T)

Type Parameters

T

The type of elements in the list.

NoteNote:

The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: SharedState. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

The BindingList(Of T) class can be used as a base class to create a two-way data-binding mechanism. BindingList(Of T) provides a concrete, generic implementation of the IBindingList interface. This is an alternative to implementing the complete IBindingList interface, which can be difficult because of the subtle interaction between IBindingList, IEditableObject, and the associated CurrencyManager. However, the typical solutions programmer will use a class that provides data binding functionality, such as BindingSource, instead of directly using BindingList(Of T).

BindingList(Of T) supports factory-created instances through the extensible AddNew method. (This same type of extensibility is also found in other classes, such as BindingSource) In addition, since this class implements the ICancelAddNew interface, it enables transactional commits or rollbacks of the new item through the EndNew and CancelNew methods.

The following code example demonstrates binding to a BindingList(Of T) component containing a business object. This is a complete example that contains a Main method.

Option Explicit On
Option Strict On
Imports System
Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Drawing
Imports System.Text
Imports System.Windows.Forms

Class Form1
    Inherits Form

    Private textBox2 As TextBox
    Private listBox1 As ListBox
    Private WithEvents button1 As Button
    Private textBox1 As TextBox
    Private randomNumber As New Random()

    Public Sub New()
        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
        Me.textBox1 = New System.Windows.Forms.TextBox()
        Me.textBox2 = New System.Windows.Forms.TextBox()
        Me.listBox1 = New System.Windows.Forms.ListBox()
        Me.button1 = New System.Windows.Forms.Button()
        Me.textBox1.Location = New System.Drawing.Point(169, 26)
        Me.textBox1.Size = New System.Drawing.Size(100, 20)
        Me.textBox1.Text = "Bracket" 
        Me.textBox2.Location = New System.Drawing.Point(169, 57)
        Me.textBox2.ReadOnly = True 
        Me.textBox2.Size = New System.Drawing.Size(100, 20)
        Me.textBox2.Text = "4343" 
        Me.listBox1.FormattingEnabled = True 
        Me.listBox1.Location = New System.Drawing.Point(12, 12)
        Me.listBox1.Size = New System.Drawing.Size(120, 95)
        Me.button1.Location = New System.Drawing.Point(180, 83)
        Me.button1.Size = New System.Drawing.Size(75, 23)
        Me.button1.Text = "Add New Item" 
        Me.ClientSize = New System.Drawing.Size(292, 266)
        Me.Controls.Add(Me.button1)
        Me.Controls.Add(Me.listBox1)
        Me.Controls.Add(Me.textBox2)
        Me.Controls.Add(Me.textBox1)
        Me.Text = "Parts Form" 
        AddHandler Me.Load, AddressOf Form1_Load

    End Sub 'New 

    Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
        InitializeListOfParts()
        listBox1.DataSource = listOfParts
        listBox1.DisplayMember = "PartName" 
    End Sub 

    ' Declare a new BindingListOfT with the Part business object. 
    Private WithEvents listOfParts As BindingList(Of Part)

    Private Sub InitializeListOfParts()

        ' Create the new BindingList of Part type.
        listOfParts = New BindingList(Of Part)

        ' Allow new parts to be added, but not removed once committed.        
        listOfParts.AllowNew = True
        listOfParts.AllowRemove = False 

        ' Raise ListChanged events when new parts are added.
        listOfParts.RaiseListChangedEvents = True 

        ' Do not allow parts to be edited.
        listOfParts.AllowEdit = False 

        ' Add a couple of parts to the list.
        listOfParts.Add(New Part("Widget", 1234))
        listOfParts.Add(New Part("Gadget", 5647))

    End Sub 

    ' Create a new part from the text in the two text boxes. 
    Private Sub listOfParts_AddingNew(ByVal sender As Object, _
        ByVal e As AddingNewEventArgs) Handles listOfParts.AddingNew
        e.NewObject = New Part(textBox1.Text, Integer.Parse(textBox2.Text))

    End Sub 


    ' Add the new part unless the part number contains 
    ' spaces. In that case cancel the add. 
    Private Sub button1_Click(ByVal sender As Object, _
        ByVal e As EventArgs) Handles button1.Click

        Dim newPart As Part = listOfParts.AddNew()

        If newPart.PartName.Contains(" ") Then
            MessageBox.Show("Part names cannot contain spaces.")
            listOfParts.CancelNew(listOfParts.IndexOf(newPart))
        Else
            textBox2.Text = randomNumber.Next(9999).ToString()
            textBox1.Text = "Enter part name" 
        End If 

    End Sub

    <STAThread()> _
    Shared Sub Main()
        Application.EnableVisualStyles()
        Application.Run(New Form1())

    End Sub 
End Class 

' A simple business object for example purposes. 
Public Class Part
    Private name As String 
    Private number As Integer 

    Public Sub New()
    End Sub 

    Public Sub New(ByVal nameForPart As String, _
        ByVal numberForPart As Integer)
        PartName = nameForPart
        PartNumber = numberForPart

    End Sub 


    Public Property PartName() As String 
        Get 
            Return name
        End Get 
        Set(ByVal value As String)
            name = Value
        End Set 
    End Property 

    Public Property PartNumber() As Integer 
        Get 
            Return number
        End Get 
        Set(ByVal value As Integer)
            number = Value
        End Set 
    End Property 
End Class

System.Object
  System.Collections.ObjectModel.Collection(Of T)
    System.ComponentModel.BindingList(Of T)

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0

.NET Compact Framework

Supported in: 3.5, 2.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

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