ListControl.ValueMember-Eigenschaft

Ruft die Eigenschaft ab, die als tatsächlicher Wert für die Elemente im ListControl verwendet werden soll, oder legt diese fest.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in system.windows.forms.dll)

Syntax

'Declaration
Public Property ValueMember As String
'Usage
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)

Eigenschaftenwert

Ein String, der den Namen einer Objekteigenschaft darstellt, die sich in einer von der DataSource-Eigenschaft angegebenen Auflistung befindet. Der Standardwert ist eine leere Zeichenfolge ("").

Ausnahmen

Ausnahmetyp	Bedingung
ArgumentException	Die angegebene Eigenschaft kann für das Objekt nicht gefunden werden, das von der DataSource-Eigenschaft angegeben wird.

Hinweise

Beim Binden von Daten müssen Sie den Inhalt der ValueMember-Eigenschaft festlegen.

Sie können die ValueMember-Eigenschaft löschen, indem Sie für die Eigenschaft eine leere Zeichenfolge ("") oder NULL (Nothing in Visual Basic) festlegen.

Durch Festlegen einer neuen ValueMember-Eigenschaft werden das ValueMemberChanged-Ereignis und das SelectedValueChanged-Ereignis ausgelöst.

Beispiel

Im folgenden Codebeispiel wird das Laden von Daten in eine ArrayList und das Festlegen des ValueMember auf eine Eigenschaft des Objekts in der Liste erläutert.

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 

Plattformen

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile für Pocket PC, Windows Mobile für Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.

Versionsinformationen

.NET Framework

Unterstützt in: 2.0, 1.1, 1.0

.NET Compact Framework

Unterstützt in: 2.0, 1.0

Siehe auch

Referenz

ListControl-Klasse
ListControl-Member
System.Windows.Forms-Namespace