HtmlSelect.ClearSelection-Methode
Löscht die Listenauswahl des HtmlSelect-Steuerelements und legt die ListItem.Selected-Eigenschaft aller Elemente auf false fest.
Namespace: System.Web.UI.HtmlControls
Assembly: System.Web (in system.web.dll)
Syntax
'Declaration
Protected Overridable Sub ClearSelection
'Usage
Me.ClearSelection
protected virtual void ClearSelection ()
protected:
virtual void ClearSelection ()
protected void ClearSelection ()
protected function ClearSelection ()
Hinweise
Die ClearSelection-Methode durchläuft die durch die Items-Eigenschaft des HtmlSelect-Steuerelements dargestellte ListItemCollection-Auflistung und legt die Selected-Eigenschaft jedes ListItem-Objekts auf false fest.
Beispiel
Im folgenden Codebeispiel wird das Überschreiben der ClearSelection-Methode in einem benutzerdefinierten Serversteuerelement veranschaulicht, sodass diese immer alle ausgewählten Elemente einer HtmlSelect-Auflistung löscht.
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB" %>
<%@ Page Language="VB" AutoEventWireup="True" %>
<HTML>
<HEAD>
<title>Custom HtmlSelect - ClearSelection - VB.NET Example</title>
<script runat="server">
Sub HtmlInputButton1_ServerClick(sender As Object, e As EventArgs)
If HtmlSelect1.SelectedIndex >= 0 Then
If HtmlSelect1.Multiple = True Then
Div1.InnerHtml = "You selected:"
Dim i As Integer
For i = 0 To HtmlSelect1.Items.Count - 1
If HtmlSelect1.Items(i).Selected = True Then
Div1.InnerHtml += "<br> " & HtmlSelect1.Items(i).Value
End If
Next i
Else
Div1.InnerHtml = "You selected " & HtmlSelect1.Value
End If
Else
Div1.InnerHtml = "You did not select an item."
End If
End Sub
</script>
</HEAD>
<body>
<form id="Form1" method="post" runat="server">
<h3>Custom HtmlSelect - ClearSelection - VB.NET Example</h3>
<p>
<aspSample:CustomHtmlSelectClearSelection
id="HtmlSelect1" multiple
name="HtmlSelect1"
runat="server">
<OPTION value="Option1">Option1</OPTION>
<OPTION value="Option2">Option2</OPTION>
<OPTION value="Option3">Option3</OPTION>
<OPTION value="Option4">Option4</OPTION>
</aspSample:CustomHtmlSelectClearSelection>
</p>
<p>
<INPUT
id="HtmlInputButton1"
runat="server"
type="button"
onserverclick="HtmlInputButton1_ServerClick"
value="Select"
name="HtmlInputButton1">
</p>
<p>
<DIV id="Div1" runat="server"
style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px"
ms_positioning="FlowLayout" />
</p>
</form>
</body>
</HTML>
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<%@ Page Language="C#" AutoEventWireup="True" %>
<HTML>
<HEAD>
<title>Custom HtmlSelect - ClearSelection - C# Example</title>
<script runat="server">
void HtmlInputButton1_ServerClick(Object sender, EventArgs e)
{
if (HtmlSelect1.SelectedIndex >= 0)
{
if (HtmlSelect1.Multiple == true)
{
Div1.InnerHtml = "You selected:";
for (int i=0; i<=HtmlSelect1.Items.Count - 1; i++)
{
if (HtmlSelect1.Items[i].Selected == true)
{
Div1.InnerHtml += "<br> " + HtmlSelect1.Items[i].Value;
}
}
}
else
{
Div1.InnerHtml = "You selected " + HtmlSelect1.Value;
}
}
else
{
Div1.InnerHtml = "You did not select an item.";
}
}
</script>
</HEAD>
<body>
<form id="Form1" method="post" runat="server">
<h3>Custom HtmlSelect - ClearSelection - C# Example</h3>
<p>
<aspSample:CustomHtmlSelectClearSelection
id="HtmlSelect1" multiple
name="HtmlSelect1"
runat="server">
<OPTION value="Option1">Option1</OPTION>
<OPTION value="Option2">Option2</OPTION>
<OPTION value="Option3">Option3</OPTION>
<OPTION value="Option4">Option4</OPTION>
</aspSample:CustomHtmlSelectClearSelection>
</p>
<p>
<INPUT
id="HtmlInputButton1"
runat="server"
type="button"
onserverclick="HtmlInputButton1_ServerClick"
value="Select"
name="HtmlInputButton1">
</p>
<p>
<DIV id="Div1" runat="server"
style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px"
ms_positioning="FlowLayout" />
</p>
</form>
</body>
</HTML>
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.JSL.Controls" Assembly="Samples.AspNet.JSL" %>
<%@ Page Language="VJ#" AutoEventWireup="True" %>
<HTML>
<HEAD>
<title>Custom HtmlSelect - ClearSelection - VJ# Example</title>
<script runat="server">
void HtmlInputButton1_ServerClick(Object sender, EventArgs e)
{
if (HtmlSelect1.get_SelectedIndex() >= 0) {
if (HtmlSelect1.get_Multiple() == true) {
Div1.set_InnerHtml("You selected:");
for (int i=0; i<=HtmlSelect1.get_Items().get_Count() - 1; i++) {
if (HtmlSelect1.get_Items().get_Item(i).
get_Selected() == true) {
Div1.set_InnerHtml(Div1.get_InnerHtml() + "<br> " + HtmlSelect1.get_Items().get_Item(i).get_Value());
}
}
}
else {
Div1.set_InnerHtml("You selected " + HtmlSelect1.get_Value());
}
}
else {
Div1.set_InnerHtml("You did not select an item.");
}
} //HtmlInputButton1_ServerClick
</script>
</HEAD>
<body>
<form id="Form1" method="post" runat="server">
<h3>Custom HtmlSelect - ClearSelection - VJ# Example</h3>
<p>
<aspSample:CustomHtmlSelectClearSelection
id="HtmlSelect1" multiple
name="HtmlSelect1"
runat="server">
<OPTION value="Option1">Option1</OPTION>
<OPTION value="Option2">Option2</OPTION>
<OPTION value="Option3">Option3</OPTION>
<OPTION value="Option4">Option4</OPTION>
</aspSample:CustomHtmlSelectClearSelection>
</p>
<p>
<INPUT
id="HtmlInputButton1"
runat="server"
type="button"
onserverclick="HtmlInputButton1_ServerClick"
value="Select"
name="HtmlInputButton1">
</p>
<p>
<DIV id="Div1" runat="server"
style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px"
ms_positioning="FlowLayout" />
</p>
</form>
</body>
</HTML>
<AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
Public NotInheritable Class CustomHtmlSelectClearSelection
Inherits System.Web.UI.HtmlControls.HtmlSelect
Protected Overrides Sub ClearSelection()
' For each item in the Items collection,
' set the Selected property to false.
Dim i As Integer
For i = 0 To Items.Count - 1
Items(i).Selected = False
Next i
End Sub
End Class
using System.Web;
using System.Security.Permissions;
namespace Samples.AspNet.CS.Controls
{
[AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
public sealed class CustomHtmlSelectClearSelection : System.Web.UI.HtmlControls.HtmlSelect
{
protected override void ClearSelection()
{
// For each item in the Items collection,
// set the Selected property to false.
for (int i=0; i < Items.Count; i++)
Items[i].Selected = false;
}
}
}
package Samples.AspNet.JSL.Controls;
public class CustomHtmlSelectClearSelection
extends System.Web.UI.HtmlControls.HtmlSelect
{
protected void ClearSelection()
{
// For each item in the Items collection,
// set the Selected property to false.
for (int i = 0; i < get_Items().get_Count(); i++) {
get_Items().get_Item(i).set_Selected(false);
}
} //ClearSelection
} //CustomHtmlSelectClearSelection
Plattformen
Windows 98, Windows 2000 SP4, 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
Siehe auch
Referenz
HtmlSelect-Klasse
HtmlSelect-Member
System.Web.UI.HtmlControls-Namespace
ListItemCollection
ListItem
Selected
Items