ListControl.ValueMember 属性
获取或设置一个属性，该属性将用作 ListControl 中的项的实际值。
**命名空间:**System.Windows.Forms
**程序集:**System.Windows.Forms（在 system.windows.forms.dll 中）
语法
声明
Public Property ValueMember As String
用法
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);
}
/** @property */
public String get_ValueMember ()
/** @property */
public void set_ValueMember (String value)
public function get ValueMember () : String
public function set ValueMember (value : String)
属性值
一个 String，表示 DataSource 属性指定的集合中包含的对象属性的名称。默认值为空字符串 ("")。
异常
| 异常类型 | 条件 |
|---|---|
在由 DataSource 属性指定的对象上无法找到指定的属性。 |
备注
如果要绑定数据，就要指定 ValueMember 属性的内容。
可以通过将 ValueMember 属性设置成空字符串 ("") 或 空引用（在 Visual Basic 中为 Nothing） 来清除该属性。
设置新的 ValueMember 属性会引发 ValueMemberChanged 和 SelectedValueChanged 事件。
示例
下面的代码示例演示如何将数据加载到 ArrayList 中，并将 ValueMember 设置为列表中的对象的一个属性。
Imports System
Imports System.Windows.Forms
Imports System.Drawing
Imports System.Collections
Public Class USState
Private myShortName As String
Private myLongName As String
Public Sub New(strLongName As String, 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
Public Overrides Function ToString() As String
Return Me.ShortName + " - " + Me.LongName
End Function 'ToString
End Class 'USState
Public Class ListBoxSample3
Inherits Form
Private ListBox1 As New ListBox()
Private textBox1 As New TextBox()
<STAThread()> _
Shared Sub Main()
Application.Run(New ListBoxSample3())
End Sub 'Main
Public Sub New()
Me.ClientSize = New Size(292, 181)
Me.Text = "ListBox Sample3"
ListBox1.Location = New Point(24, 16)
ListBox1.Name = "ListBox1"
ListBox1.Size = New Size(232, 130)
textBox1.Location = New Point(24, 160)
textBox1.Name = "textBox1"
textBox1.Size = New Size(240, 24)
Me.Controls.AddRange(New Control() {ListBox1, textBox1})
' Populates the list box using DataSource.
' DisplayMember is used to display just the long name of each state.
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"))
AddHandler ListBox1.SelectedValueChanged, AddressOf ListBox1_SelectedValueChanged
ListBox1.DataSource = USStates
ListBox1.DisplayMember = "LongName"
ListBox1.ValueMember = "ShortName"
End Sub 'New
Private Sub InitializeComponent()
End Sub 'InitializeComponent
Private Sub ListBox1_SelectedValueChanged(sender As Object, e As EventArgs)
If ListBox1.SelectedIndex <> - 1 Then
textBox1.Text = ListBox1.SelectedValue.ToString()
End If
End Sub 'ListBox1_SelectedValueChanged
End Class 'ListBoxSample3
using System;
using System.Windows.Forms ;
using System.Drawing ;
using System.Collections ;
namespace MyListControlSample
{
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 ;
}
}
public override string ToString()
{
return this.ShortName + " - " + this.LongName;
}
}
public class ListBoxSample3:Form
{
private ListBox ListBox1 = new ListBox();
private TextBox textBox1 = new TextBox() ;
[STAThread]
static void Main()
{
Application.Run(new ListBoxSample3()) ;
}
public ListBoxSample3()
{
this.ClientSize = new Size(292, 181) ;
this.Text = "ListBox Sample3" ;
ListBox1.Location = new Point(24, 16) ;
ListBox1.Name = "ListBox1" ;
ListBox1.Size = new Size(232, 130) ;
textBox1.Location = new Point(24, 160) ;
textBox1.Name = "textBox1" ;
textBox1.Size = new Size(240, 24) ;
this.Controls.AddRange(new Control[] {ListBox1, textBox1}) ;
// Populates the list box using DataSource.
// DisplayMember is used to display just the long name of each state.
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.SelectedValueChanged += new EventHandler(ListBox1_SelectedValueChanged);
ListBox1.DataSource = USStates ;
ListBox1.DisplayMember = "LongName" ;
ListBox1.ValueMember = "ShortName" ;
}
private void InitializeComponent()
{
}
private void ListBox1_SelectedValueChanged(object sender, EventArgs e)
{
if (ListBox1.SelectedIndex != -1)
textBox1.Text = ListBox1.SelectedValue.ToString();
}
}
}
#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;
}
}
virtual String^ ToString() override
{
return String::Concat( this->ShortName, " - ", this->LongName );
}
};
public ref class ListBoxSample3: public Form
{
private:
ListBox^ ListBox1;
TextBox^ textBox1;
public:
ListBoxSample3()
{
ListBox1 = gcnew ListBox;
textBox1 = gcnew TextBox;
this->ClientSize = System::Drawing::Size( 292, 181 );
this->Text = "ListBox Sample3";
ListBox1->Location = Point(24,16);
ListBox1->Name = "ListBox1";
ListBox1->Size = System::Drawing::Size( 232, 130 );
textBox1->Location = Point(24,160);
textBox1->Name = "textBox1";
textBox1->Size = System::Drawing::Size( 240, 24 );
array<Control^>^temp2 = {ListBox1,textBox1};
this->Controls->AddRange( temp2 );
// Populates the list box using 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->SelectedValueChanged += gcnew EventHandler( this, &ListBoxSample3::ListBox1_SelectedValueChanged );
ListBox1->DataSource = USStates;
ListBox1->DisplayMember = "LongName";
ListBox1->ValueMember = "ShortName";
}
void InitializeComponent(){}
private:
void ListBox1_SelectedValueChanged( Object^ /*sender*/, EventArgs^ /*e*/ )
{
if ( ListBox1->SelectedIndex != -1 )
textBox1->Text = ListBox1->SelectedValue->ToString();
}
};
[STAThread]
int main()
{
Application::Run( gcnew ListBoxSample3 );
}
package MyListControlSample;
import System.*;
import System.Windows.Forms.*;
import System.Drawing.*;
import System.Collections.*;
public class USState
{
private String myShortName;
private String myLongName;
public USState(String strLongName, String strShortName)
{
this.myShortName = strShortName;
this.myLongName = strLongName;
} //USState
/** @property
*/
public String get_ShortName()
{
return myShortName;
}//get_ShortName
/** @property
*/
public String get_LongName()
{
return myLongName;
}//get_LongName
public String ToString()
{
return this.get_ShortName() + " - " + this.get_LongName();
} //ToString
} //USState
public class ListBoxSample3 extends Form
{
private ListBox listBox1 = new ListBox();
private TextBox textBox1 = new TextBox();
/** @attribute STAThread()
*/
public static void main(String[] args)
{
Application.Run(new ListBoxSample3());
} //main
public ListBoxSample3()
{
this.set_ClientSize(new Size(292, 181));
this.set_Text("ListBox Sample3");
listBox1.set_Location(new Point(24, 16));
listBox1.set_Name("ListBox1");
listBox1.set_Size(new Size(232, 130));
textBox1.set_Location(new Point(24, 160));
textBox1.set_Name("textBox1");
textBox1.set_Size(new Size(240, 24));
this.get_Controls().AddRange(new Control[] { listBox1, textBox1 });
// Populates the list box using DataSource.
// DisplayMember is used to display just the long name of each state.
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.add_SelectedValueChanged(
new EventHandler(listBox1_SelectedValueChanged));
listBox1.set_DataSource(uSStates);
listBox1.set_DisplayMember("LongName");
listBox1.set_ValueMember("ShortName");
} //ListBoxSample3
private void InitializeComponent()
{
} //InitializeComponent
private void listBox1_SelectedValueChanged(Object sender, EventArgs e)
{
if (listBox1.get_SelectedIndex() != -1) {
textBox1.set_Text(listBox1.get_SelectedValue().ToString());
}
} //listBox1_SelectedValueChanged
} //ListBoxSample3
平台
Windows 98、Windows 2000 SP4、Windows CE、Windows Millennium Edition、Windows Mobile for Pocket PC、Windows Mobile for Smartphone、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition
.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表，请参见系统要求。
版本信息
.NET Framework
受以下版本支持：2.0、1.1、1.0
.NET Compact Framework
受以下版本支持：2.0、1.0