Represents a data item in a data-bound list control. This class cannot be inherited.
Namespace: System.Web.UI.WebControls
Assembly: System.Web (in system.web.dll)
Visual Basic (Declaration)
Public NotInheritable Class ListItem
Implements IStateManager, IParserAccessor, IAttributeAccessor
public sealed class ListItem : IStateManager, IParserAccessor, IAttributeAccessor
public ref class ListItem sealed : IStateManager, IParserAccessor, IAttributeAccessor
public final class ListItem implements IStateManager, IParserAccessor,
IAttributeAccessor
public final class ListItem implements IStateManager, IParserAccessor,
IAttributeAccessor
A ListItem control represents an individual data item within a data-bound list control, such as a ListBox or a RadioButtonList control.
There are several ways to specify the text displayed for an item in the list control. The most common method is by placing text in the inner HTML content. The inner HTML content is the text between the opening and closing tags of the ListItem control. You can also use the Text property to specify the text displayed in the list control for the item.
The Value property allows you to associate a value with the item in the list control, in addition to the text displayed in the control. For example, you can display text for an item in the list control, such as "Item 1", and use the Value property to specify a value for that item, such as "$1.99".
You can have any combination of the inner HTML content, Text, or Value properties set. The resulting HTML output for the ListItem control depends on the combination of these three properties that are set. For example, if all three properties are set as follows:
<asp:ListItem Value="Value 1" Text="Item 1">Inner 1</asp:ListItem>
The inner HTML content is used for rendered inner HTML content and the Value property is used for the Value attribute. The resulting HTML rendering output is:
<option value="Value 1">Inner 1</option>
The following table lists the combination of set properties and the corresponding property used for the rendered inner HTML content and Value attribute. The three columns on the left list the combination of set properties. The two columns on the right list which property value is used for the corresponding attribute.
| Inner HTML content | Text property | Value property | Rendered Inner HTML content | Rendered Value attribute |
| Set | Set | Set | Inner HTML content | Value property |
| Set | Set | Not set | Inner HTML content | Inner HTML content |
| Set | Not set | Set | Inner HTML content | Value property |
| Set | Not set | Not set | Inner HTML content | Inner HTML text |
| Not set | Set | Set | Text property | Value property |
| Not set | Set | Not set | Text property | Text property |
| Not set | Not set | Set | Value property | Value property |
| Not set | Not set | Not set | Not set | Not set |
.gif) Note |
|---|
| Because the Text and Value properties each have a default value of an empty string, it is possible to have empty list items in the list control. |
When a list control is displayed, any ListItem control with its Selected property set to true appears highlighted in the control.
The ListItem control provides the Enabled property to allow you to specify whether a ListItem control is enabled or disabled. A ListItem control that is disabled is dimmed to indicate that it cannot be selected. Use this property to disable a ListItem control in either a RadioButtonList control or a CheckBoxList control.
| Note |
|---|
| You cannot use this property to disable a ListItem control in a DropDownList control or ListBox control. |
For a list of initial property values for an instance of ListItem, see the ListItem constructor.
The following example illustrates the use of ListItem controls within a ListBox control.
| Note |
|---|
| The following code samples use the single-file code model and may not work correctly if copied directly into a code-behind file. Each code sample must be copied into an empty text file that has an .aspx extension. For more information on the Web Forms code model, see ASP.NET Web Page Code Model. |
<%@ Page Language="VB" AutoEventWireup="True" %>
<html>
<head>
<script language="VB" runat="server">
Sub SubmitBtn_Click(Sender As Object, e As EventArgs)
If ListBox1.SelectedIndex > -1 Then
Label1.Text = "You chose: " & ListBox1.SelectedItem.Text
Label1.Text &= "<br> with value: " & ListBox1.SelectedItem.Value
End If
End Sub
</script>
</head>
<body>
<h3>ListBox Example</h3>
<p>
<form runat=server>
<asp:ListBox id=ListBox1 Width="100px" runat="server">
<asp:ListItem>Item 1</asp:ListItem>
<asp:ListItem>Item 2</asp:ListItem>
<asp:ListItem>Item 3</asp:ListItem>
<asp:ListItem Value="Value 4">Item 4</asp:ListItem>
<asp:ListItem Text="Item 5" Value="Value 5" Selected="True"/>
<asp:ListItem>Item 6</asp:ListItem>
</asp:ListBox>
<asp:button Text="Submit" OnClick="SubmitBtn_Click" runat="server" />
<p>
<asp:Label id=Label1 font-name="Verdana" font-size="10pt" runat="server"/>
</form>
</body>
</html>
<%@ Page Language="C#" AutoEventWireup="True" %>
<html>
<head>
<script language="C#" runat="server">
void SubmitBtn_Click(Object Sender, EventArgs e) {
if (ListBox1.SelectedIndex > -1) {
Label1.Text="You chose: " + ListBox1.SelectedItem.Text;
Label1.Text+="<br> with value: " + ListBox1.SelectedItem.Value;
}
}
</script>
</head>
<body>
<h3>ListBox Example</h3>
<p>
<form runat=server>
<asp:ListBox id=ListBox1 Width="100px" runat="server">
<asp:ListItem>Item 1</asp:ListItem>
<asp:ListItem>Item 2</asp:ListItem>
<asp:ListItem>Item 3</asp:ListItem>
<asp:ListItem Value="Value 4">Item 4</asp:ListItem>
<asp:ListItem Text="Item 5" Value="Value 5" Selected="True"/>
<asp:ListItem>Item 6</asp:ListItem>
</asp:ListBox>
<asp:button Text="Submit" OnClick="SubmitBtn_Click" runat="server" />
<p>
<asp:Label id=Label1 font-name="Verdana" font-size="10pt" runat="server"/>
</form>
</body>
</html>
<%@ Page Language="JScript" AutoEventWireup="True" %>
<html>
<head>
<script language="JSCRIPT" runat="server">
function SubmitBtn_Click(Sender : Object, e : EventArgs){
if(ListBox1.SelectedIndex > -1){
Label1.Text = "You chose: " + ListBox1.SelectedItem.Text
Label1.Text += "<br> with value: " + ListBox1.SelectedItem.Value
}
}
</script>
</head>
<body>
<h3>ListBox Example</h3>
<p>
<form runat=server>
<asp:ListBox id=ListBox1 Width="100px" runat="server">
<asp:ListItem>Item 1</asp:ListItem>
<asp:ListItem>Item 2</asp:ListItem>
<asp:ListItem>Item 3</asp:ListItem>
<asp:ListItem Value="Value 4">Item 4</asp:ListItem>
<asp:ListItem Text="Item 5" Value="Value 5" Selected="True"/>
<asp:ListItem>Item 6</asp:ListItem>
</asp:ListBox>
<asp:button Text="Submit" OnClick="SubmitBtn_Click" runat="server" />
<p>
<asp:Label id=Label1 font-name="Verdana" font-size="10pt" runat="server"/>
</form>
</body>
</html>
<!-- This example demonstrates how to select multiple items from a DataList
and add the selected items to a DataGrid. The example uses a For Each loop
to iterate through the ListItem objects in the ListItemCollection of ListBox1. -->
<br /><span space="preserve">...</span><br /><%@ Page language="VB" AutoEventWireup="true"%>
<%@ Import Namespace="System.Data" %>
<HTML>
<HEAD>
<SCRIPT runat="server">
' Global Variables.
Private dv As DataView
Private dt As New DataTable()
Private Sub Page_Load(sender As Object, e As System.EventArgs)
' Set the number of rows displayed in the ListBox to be
' the number of items in the ListBoxCollection.
ListBox1.Rows = ListBox1.Items.Count
' If the DataTable is already stored in the Web form's default
' HttpSessionState variable, then don't recreate the DataTable.
If Session("data") Is Nothing Then
' Add columns to the DataTable.
dt.Columns.Add(New DataColumn("Item"))
dt.Columns.Add(New DataColumn("Price"))
' Store the DataTable in the Session variable so it can be
' accessed again later.
Session("data") = dt
' Use the table to create a DataView, because the DataGrid
' can only bind to a data source that implements IEnumerable.
dv = New DataView(dt)
' Set the DataView as the data source, and bind it to the DataGrid.
DataGrid1.DataSource = dv
DataGrid1.DataBind()
End If
End Sub
Private Sub addButton_Click(sender As Object, e As System.EventArgs)
' Add the items selected in ListBox1 to DataGrid1.
Dim item As ListItem
For Each item In ListBox1.Items
If item.Selected Then
' Add the item to the DataGrid.
' First, get the DataTable from the Session variable.
dt = CType(Session("data"), DataTable)
If Not (dt Is Nothing) Then
' Create a new DataRow in the DataTable.
Dim dr As DataRow
dr = dt.NewRow()
' Add the item to the new DataRow.
dr("Item") = item.Text
' Add the item's value to the DataRow.
dr("Price") = item.Value
' Add the DataRow to the DataTable.
dt.Rows.Add(dr)
' Rebind the data to DataGrid1.
dv = new DataView(dt)
DataGrid1.DataSource = dv
DataGrid1.DataBind()
End If
End If
Next item
End Sub
</SCRIPT>
</HEAD>
<BODY>
<form runat="server">
<h3> ListItemCollection Example </h3>
<table cellpadding="6" border="0">
<tr>
<td valign="top">
<asp:ListBox id="ListBox1" runat="server" SelectionMode="Multiple">
<asp:ListItem Value=".89">apples</asp:ListItem>
<asp:ListItem Value=".49">bananas</asp:ListItem>
<asp:ListItem Value="2.99">cherries</asp:ListItem>
<asp:ListItem Value="1.49">grapes</asp:ListItem>
<asp:ListItem Value="2.00">mangos</asp:ListItem>
<asp:ListItem Value="1.09">oranges</asp:ListItem>
</asp:ListBox>
</td>
<td valign="top">
<asp:Button id="addButton" runat="server" Text="Add -->"
Width="100px" OnClick="addButton_Click"></asp:Button>
</td>
<td valign="top">
<asp:DataGrid Runat="server" ID="DataGrid1" CellPadding="4">
</asp:DataGrid>
</td>
</tr>
</table>
</form>
</body>
</HTML>
<!-- This example demonstrates how to select multiple items from a DataList and add the
selected items to a DataGrid. The example uses a foreach loop to iterate through
the ListItem objects in the ListItemCollection of ListBox1. -->
<br /><span space="preserve">...</span><br /><%@ Page language="c#" AutoEventWireup="true"%>
<%@ Import Namespace="System.Data" %>
<HTML>
<HEAD>
<SCRIPT language="C#" runat="server">
// Global Variables.
private DataView dv;
private DataTable dt = new DataTable();
private void Page_Load(object sender, System.EventArgs e)
{
// Set the number of rows displayed in the ListBox to be
// the number of items in the ListBoxCollection.
ListBox1.Rows = ListBox1.Items.Count;
// If the DataTable is already stored in the Web form's default
// HttpSessionState variable, then don't recreate the DataTable.
if (Session["data"] == null)
{
// Add columns to the DataTable.
dt.Columns.Add(new DataColumn("Item"));
dt.Columns.Add(new DataColumn("Price"));
// Store the DataTable in the Session variable so it can
// be accessed again later.
Session["data"] = dt;
// Use the table to create a DataView, because the DataGrid
// can only bind to a data source that implements IEnumerable.
dv = new DataView(dt);
// Set the DataView as the data source, and bind it to the DataGrid.
DataGrid1.DataSource = dv;
DataGrid1.DataBind();
}
}
private void addButton_Click(object sender, System.EventArgs e)
{
// Add the items selected in ListBox1 to DataGrid1.
foreach (ListItem item in ListBox1.Items)
{
if (item.Selected)
{
// Add the item to the DataGrid.
// First, get the DataTable from the Session variable.
dt = (DataTable)Session["data"];
if (dt != null)
{
// Create a new DataRow in the DataTable.
DataRow dr = dt.NewRow();
// Add the item to the new DataRow.
dr["Item"] = item.Text;
// Add the item's value to the DataRow.
dr["Price"] = item.Value;
// Add the DataRow to the DataTable.
dt.Rows.Add(dr);
// Rebind the data to DataGrid1.
dv = new DataView(dt);
DataGrid1.DataSource = dv;
DataGrid1.DataBind();
}
}
}
}
</SCRIPT>
</HEAD>
<BODY>
<form runat="server">
<h3> ListItemCollection Example </h3>
<table cellpadding="6" border="0">
<tr>
<td valign="top">
<asp:ListBox id="ListBox1" runat="server" SelectionMode="Multiple">
<asp:ListItem Value=".89">apples</asp:ListItem>
<asp:ListItem Value=".49">bananas</asp:ListItem>
<asp:ListItem Value="2.99">cherries</asp:ListItem>
<asp:ListItem Value="1.49">grapes</asp:ListItem>
<asp:ListItem Value="2.00">mangos</asp:ListItem>
<asp:ListItem Value="1.09">oranges</asp:ListItem>
</asp:ListBox>
</td>
<td valign="top">
<asp:Button id="addButton" runat="server" Text="Add -->"
Width="100px" OnClick="addButton_Click"></asp:Button>
</td>
<td valign="top">
<asp:DataGrid Runat="server" ID="DataGrid1" CellPadding="4">
</asp:DataGrid>
</td>
</tr>
</table>
</form>
</body>
</HTML>
System.Object
System.Web.UI.WebControls.ListItem
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 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.
.NET Framework
Supported in: 2.0, 1.1, 1.0