Introduction
Use the ListBox control to create a list control that allows single or multiple item selection. Use the Rows property to specify the height of the control. To enable multiple item selection, set the SelectionMode property to ListSelectionMode.Multiple.
To specify the items that you want to appear in the ListBox control, place a ListItem element for each entry between the opening and closing tags of the ListBox control.
Use the Items collection to examine the ListItem objects contained in the ListBox control. For example, you can determine the selected item(s) in the ListBox control by enumerating the Items collection and testing the Selected value for each ListItem element.
The ListBox control also supports data binding. To bind the control to a data source, first create a data source, such as one of the DataSourceControl objects, that contains the items to display in the control. Next, use the DataBind method to bind the data source to the ListBox control.
Use the DataTextField and DataValueField properties to specify which field in the data source to bind to the Text and Value properties, respectively, of each list item in the control. The ListBox control will now display the information from the data source.
Example 1:
The following example demonstrates how to create a ListBox control.
<%@ Page Language="C#" AutoEventWireup="True" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head> <title>ListBox Example</title> <script language="C#" runat="server"> void SubmitBtn_Click(Object sender, EventArgs e) { if (ListBox1.SelectedIndex > -1) Label1.Text="You chose: " + ListBox1.SelectedItem.Text; } </script> </head> <body> <h3>ListBox Example</h3> <form id="form1" runat="server"> <asp:ListBox id="ListBox1" Rows="6" Width="100px" SelectionMode="Single" runat="server"> <asp:ListItem>Item 1</asp:ListItem> <asp:ListItem>Item 2</asp:ListItem> <asp:ListItem>Item 3</asp:ListItem> <asp:ListItem>Item 4</asp:ListItem> <asp:ListItem>Item 5</asp:ListItem> <asp:ListItem>Item 6</asp:ListItem> </asp:ListBox> <asp:button id="Button1" Text="Submit" OnClick="SubmitBtn_Click" runat="server" /> <asp:Label id="Label1" Font-Names="Verdana" Font-Size="10pt" runat="server"/> </form> </body> </html>
Example 2:
The following example shows how to create a ListBox control that supports multiple selections.<html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <script language="C#" runat="server"> void SubmitBtn_Click(Object sender, EventArgs e) { string msg = ""; foreach (ListItem li in ListBox1.Items) { if (li.Selected == true) { msg += "<BR>" + li.Text + " is selected."; } } Label1.Text = msg; } </script> </head> <body> <h3>ListBox Example</h3> <form id="Form1" runat=server> <asp:ListBox id="ListBox1" Rows="6" Width="100px" SelectionMode="Multiple" runat="server"> <asp:ListItem>Item 1</asp:ListItem> <asp:ListItem>Item 2</asp:ListItem> <asp:ListItem>Item 3</asp:ListItem> <asp:ListItem>Item 4</asp:ListItem> <asp:ListItem>Item 5</asp:ListItem> <asp:ListItem>Item 6</asp:ListItem> </asp:ListBox> <asp:button id="Button1" Text="Submit" OnClick="SubmitBtn_Click" runat="server" /> <asp:Label id="Label1" Font-Name="Verdana" Font-Size="10pt" runat="server"/> </form> </body> </html>Example 3:
The following example demonstrates how to create a ListBox control through data binding.<%@ Page Language="C#" AutoEventWireup="True" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head> <title>Data Binding ListBox</title> <script language="C#" runat="server"> void Page_Load(Object sender, EventArgs e) { if (!IsPostBack) { ArrayList values = new ArrayList(); values.Add ("Item 1"); values.Add ("Item 2"); values.Add ("Item 3"); values.Add ("Item 4"); values.Add ("Item 5"); values.Add ("Item 6"); ListBox1.DataSource = values; ListBox1.DataBind(); } } void SubmitBtn_Click(Object sender, EventArgs e) { if ( ListBox1.SelectedIndex > -1 ) Label1.Text = "You chose: " + ListBox1.SelectedItem.Text; } </script> </head> <body> <form id="form1" runat="server"> <h3>Data Binding ListBox</h3> <asp:ListBox id="ListBox1" Width="100px" runat="server"/> <asp:button id="Button1" Text="Submit" OnClick="SubmitBtn_Click" runat="server" /> <asp:Label id="Label1" Font-Names="Verdana" font-size="10pt" runat="server"/> </form> </body> </html>
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