ListItemCollection.Item[Int32] 属性
定义
重要
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获取集合中指定索引处的 ListItem。
public:
property System::Web::UI::WebControls::ListItem ^ default[int] { System::Web::UI::WebControls::ListItem ^ get(int index); };public System.Web.UI.WebControls.ListItem this[int index] { get; }member this.Item(int) : System.Web.UI.WebControls.ListItemDefault Public ReadOnly Property Item(index As Integer) As ListItem参数
属性值
集合中指定索引处的 ListItem 对象。
示例
下面的代码示例演示如何从 ListBox 控件中选择多个项，并将所选项添加到 DataGrid 控件。 该示例使用 foreach 循环来循环访问 ListItem 控件集合ListBox中的 ListItemCollection 对象。
<%@ Page language="c#" AutoEventWireup="true"%>
<%@ Import Namespace="System.Data" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script language="C#" runat="server">
// Global Variables.
private DataView dv;
private DataTable dt = new DataTable();
private void Page_Load(object sender, System.EventArgs e)
{
// <Snippet4>
// Set the number of rows displayed in the ListBox to be
// the number of items in the ListBoxCollection.
ListBox1.Rows = ListBox1.Items.Count;
// </Snippet4>
// 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)
{
// <Snippet5>
// 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);
// </Snippet5>
// Rebind the data to DataGrid1.
dv = new DataView(dt);
DataGrid1.DataSource = dv;
DataGrid1.DataBind();
}
}
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title> ListItemCollection Example </title>
</head>
<body>
<form id="form1" 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>
<%@ Page language="VB" AutoEventWireup="true"%>
<%@ Import Namespace="System.Data" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<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)
' <Snippet4>
' Set the number of rows displayed in the ListBox to be
' the number of items in the ListBoxCollection.
ListBox1.Rows = ListBox1.Items.Count
' </Snippet4>
' 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)
' <Snippet5>
' 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)
' </Snippet5>
' Rebind the data to DataGrid1.
dv = new DataView(dt)
DataGrid1.DataSource = dv
DataGrid1.DataBind()
End If
End If
Next item
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title> ListItemCollection Example </title>
</head>
<body>
<form id="form1" 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>
注解
使用此索引器通过数组表示法从ListItemCollection指定索引处的 获取 ListItem 。
