Gets or sets the property to use as the actual value for the items in the ListControl.
Namespace:
System.Windows.Forms
Assembly:
System.Windows.Forms (in System.Windows.Forms.dll)
Visual Basic (Declaration)
Public Property ValueMember As String
Dim instance As ListControl
Dim value As String
value = instance.ValueMember
instance.ValueMember = value
public string ValueMember { get; set; }
public:
property String^ ValueMember {
String^ get ();
void set (String^ value);
}
public function get ValueMember () : String
public function set ValueMember (value : String)
Property Value
Type:
System..::.StringA String representing the name of an object property that is contained in the collection specified by the DataSource property. The default is an empty string ("").
Specify the contents of the ValueMember property in cases where you bind data.
You can clear the ValueMember property by setting the property to an empty string ("") or nullNothingnullptra null reference (Nothing in Visual Basic).
Setting a new ValueMember property raises the ValueMemberChanged and SelectedValueChanged events.
The following code example shows loading the data into an ArrayList and setting the ValueMember to a property of the object in the list.
Imports System
Imports System.Windows.Forms
Imports System.Drawing
Imports System.Collections
Public Class ListBoxSample3
Inherits Form
Private ListBox1 As New ListBox()
Private label1 As New Label()
Private textBox1 As New TextBox()
<STAThread()> _
Shared Sub Main()
Application.Run(New ListBoxSample3())
End Sub 'Main
Public Sub New()
Me.ClientSize = New Size(307, 206)
Me.Text = "ListBox Sample3"
ListBox1.Location = New Point(54, 16)
ListBox1.Name = "ListBox1"
ListBox1.Size = New Size(240, 130)
label1.Location = New Point(14, 150)
label1.Name = "label1"
label1.Size = New Size(40, 24)
label1.Text = "Value"
textBox1.Location = New Point(54, 150)
textBox1.Name = "textBox1"
textBox1.Size = New Size(240, 24)
Me.Controls.AddRange(New Control() {ListBox1, label1, textBox1})
' Populate the list box using an array as DataSource.
Dim USStates As New ArrayList()
USStates.Add(New USState("Alabama", "AL"))
USStates.Add(New USState("Washington", "WA"))
USStates.Add(New USState("West Virginia", "WV"))
USStates.Add(New USState("Wisconsin", "WI"))
USStates.Add(New USState("Wyoming", "WY"))
ListBox1.DataSource = USStates
' Set the long name as the property to be displayed and the short
' name as the value to be returned when a row is selected. Here
' these are properties; if we were binding to a database table or
' query these could be column names.
ListBox1.DisplayMember = "LongName"
ListBox1.ValueMember = "ShortName"
' Bind the SelectedValueChanged event to our handler for it.
AddHandler ListBox1.SelectedValueChanged, AddressOf ListBox1_SelectedValueChanged
' Ensure the form opens with no rows selected.
ListBox1.ClearSelected()
End Sub 'New
Private Sub InitializeComponent()
End Sub 'InitializeComponent
Private Sub ListBox1_SelectedValueChanged(ByVal sender As Object, ByVal e As EventArgs)
If ListBox1.SelectedIndex <> -1 Then
textBox1.Text = ListBox1.SelectedValue.ToString()
' If we also wanted to get the displayed text we could use
' the SelectedItem item property:
' Dim s = CType(ListBox1.SelectedItem, USState).LongName
End If
End Sub 'ListBox1_SelectedValueChanged
End Class 'ListBoxSample3
Public Class USState
Private myShortName As String
Private myLongName As String
Public Sub New(ByVal strLongName As String, ByVal strShortName As String)
Me.myShortName = strShortName
Me.myLongName = strLongName
End Sub 'New
Public ReadOnly Property ShortName() As String
Get
Return myShortName
End Get
End Property
Public ReadOnly Property LongName() As String
Get
Return myLongName
End Get
End Property
End Class 'USState
using System;
using System.Windows.Forms;
using System.Drawing;
using System.Collections;
namespace MyListControlSample
{
public class ListBoxSample3 : Form
{
private ListBox ListBox1 = new ListBox();
private Label label1 = new Label();
private TextBox textBox1 = new TextBox();
[STAThread]
static void Main()
{
Application.Run(new ListBoxSample3());
}
public ListBoxSample3()
{
this.ClientSize = new Size(307, 206);
this.Text = "ListBox Sample3";
ListBox1.Location = new Point(54, 16);
ListBox1.Name = "ListBox1";
ListBox1.Size = new Size(240, 130);
label1.Location = new Point(14, 150);
label1.Name = "label1";
label1.Size = new Size(40, 24);
label1.Text = "Value";
textBox1.Location = new Point(54, 150);
textBox1.Name = "textBox1";
textBox1.Size = new Size(240, 24);
this.Controls.AddRange(new Control[] { ListBox1, label1, textBox1 });
// Populate the list box using an array as DataSource.
ArrayList USStates = new ArrayList();
USStates.Add(new USState("Alabama", "AL"));
USStates.Add(new USState("Washington", "WA"));
USStates.Add(new USState("West Virginia", "WV"));
USStates.Add(new USState("Wisconsin", "WI"));
USStates.Add(new USState("Wyoming", "WY"));
ListBox1.DataSource = USStates;
// Set the long name as the property to be displayed and the short
// name as the value to be returned when a row is selected. Here
// these are properties; if we were binding to a database table or
// query these could be column names.
ListBox1.DisplayMember = "LongName";
ListBox1.ValueMember = "ShortName";
// Bind the SelectedValueChanged event to our handler for it.
ListBox1.SelectedValueChanged +=
new EventHandler(ListBox1_SelectedValueChanged);
// Ensure the form opens with no rows selected.
ListBox1.ClearSelected();
}
private void InitializeComponent()
{
}
private void ListBox1_SelectedValueChanged(object sender, EventArgs e)
{
if (ListBox1.SelectedIndex != -1)
{
textBox1.Text = ListBox1.SelectedValue.ToString();
// If we also wanted to get the displayed text we could use
// the SelectedItem item property:
// string s = ((USState)ListBox1.SelectedItem).LongName;
}
}
}
public class USState
{
private string myShortName;
private string myLongName;
public USState(string strLongName, string strShortName)
{
this.myShortName = strShortName;
this.myLongName = strLongName;
}
public string ShortName
{
get
{
return myShortName;
}
}
public string LongName
{
get
{
return myLongName;
}
}
}
}
#using <System.dll>
#using <System.Drawing.dll>
#using <System.Windows.Forms.dll>
using namespace System;
using namespace System::Windows::Forms;
using namespace System::Drawing;
using namespace System::Collections;
public ref class USState
{
private:
String^ myShortName;
String^ myLongName;
public:
USState( String^ strLongName, String^ strShortName )
{
this->myShortName = strShortName;
this->myLongName = strLongName;
}
property String^ ShortName
{
String^ get()
{
return myShortName;
}
}
property String^ LongName
{
String^ get()
{
return myLongName;
}
}
};
public ref class ListBoxSample3: public Form
{
private:
ListBox^ ListBox1;
Label^ label1;
TextBox^ textBox1;
public:
ListBoxSample3()
{
ListBox1 = gcnew ListBox;
label1 = gcnew Label;
textBox1 = gcnew TextBox;
this->ClientSize = System::Drawing::Size(307, 206 );
this->Text = "ListBox Sample3";
ListBox1->Location = Point(54,16);
ListBox1->Name = "ListBox1";
ListBox1->Size = System::Drawing::Size( 240, 130 );
label1->Location = Point(14,150);
label1->Name = "label1";
label1->Size = System::Drawing::Size(40, 24);
label1->Text = "Value";
textBox1->Location = Point(54,150);
textBox1->Name = "textBox1";
textBox1->Size = System::Drawing::Size( 240, 24 );
array<Control^>^temp2 = {ListBox1,label1, textBox1};
this->Controls->AddRange( temp2 );
// Populate the list box using an array as DataSource.
// DisplayMember is used to display just the long name of each state.
ArrayList^ USStates = gcnew ArrayList;
USStates->Add( gcnew USState( "Alabama","AL" ) );
USStates->Add( gcnew USState( "Washington","WA" ) );
USStates->Add( gcnew USState( "West Virginia","WV" ) );
USStates->Add( gcnew USState( "Wisconsin","WI" ) );
USStates->Add( gcnew USState( "Wyoming","WY" ) );
ListBox1->DataSource = USStates;
ListBox1->DisplayMember = "LongName";
ListBox1->ValueMember = "ShortName";
ListBox1->SelectedValueChanged += gcnew EventHandler( this, &ListBoxSample3::ListBox1_SelectedValueChanged );
ListBox1->SetSelected(0, false);
}
void InitializeComponent(){}
private:
void ListBox1_SelectedValueChanged( Object^ /*sender*/, EventArgs^ /*e*/ )
{
textBox1->Text="";
if ( ListBox1->SelectedIndex != -1 )
textBox1->Text = ListBox1->SelectedValue->ToString();
}
};
[STAThread]
int main()
{
Application::Run( gcnew ListBoxSample3 );
}
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
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, 1.1, 1.0
.NET Compact Framework
Supported in: 3.5, 2.0, 1.0
Reference