ListBox SelectedIndexChanged Event
ListBox is an asp.net list web server control that contains a list of
selectable items. More than one item is visible in ListBox control. ListBox
SelectionMode property determines whether multiple items in the ListBox are
selectable at a time.
ListBox SelectedIndexChanged event occurs when the SelectedIndex property or the SelectedIndices collection has changed. ListBox SelectedIndex property gets or sets the zero-based index of the currently selected item. And SelectedIndices property gets a collection that contains the zero-based indexes of all currently selected items in ListBox.
For multiple selections, the ListBox SelectedIndices property returns a collection containing the indexes of all selected items. ListBox SelectedIndexChanged event works when we set the ListBox AutoPostBack property value to True and write an event handler for the OnSelectedIndexChanged property.
when a user changes the selection of an item in a single selection mode ListBox control then the SelectedIndexChanged event occurs and the page post to the web server automatically. This event also occurs when the user adds or removes an item from multiple selected items in a multi-selection mode ListBox control.
The following c# example source code demonstrates to us how can we use ListBox SelectedIndexChanged event in asp.net.
ListBox SelectedIndexChanged event occurs when the SelectedIndex property or the SelectedIndices collection has changed. ListBox SelectedIndex property gets or sets the zero-based index of the currently selected item. And SelectedIndices property gets a collection that contains the zero-based indexes of all currently selected items in ListBox.
For multiple selections, the ListBox SelectedIndices property returns a collection containing the indexes of all selected items. ListBox SelectedIndexChanged event works when we set the ListBox AutoPostBack property value to True and write an event handler for the OnSelectedIndexChanged property.
when a user changes the selection of an item in a single selection mode ListBox control then the SelectedIndexChanged event occurs and the page post to the web server automatically. This event also occurs when the user adds or removes an item from multiple selected items in a multi-selection mode ListBox control.
The following c# example source code demonstrates to us how can we use ListBox SelectedIndexChanged event in asp.net.
ListBoxOnSelectedIndexChanged.aspx
<%@ Page Language="C#" %>
<!DOCTYPE html>
<script runat="server">
protected void ListBox1_SelectedIndexChanged(object sender, System.EventArgs e)
{
Label1.Text = "Your Favorite Color: " + ListBox1.SelectedItem.Text;
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>How to use SelectedIndexChanged event in ListBox</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<h2 style="color:Maroon">ListBox: OnSelectedIndexChanged</h2>
<asp:Label
ID="Label1"
runat="server"
Font-Bold="true"
ForeColor="SeaGreen"
Font-Size="Large"
>
</asp:Label>
<br /><br />
<asp:Label
ID="Label2"
runat="server"
Font-Bold="true"
ForeColor="DarkCyan"
Text="Color List"
>
</asp:Label>
<br />
<asp:ListBox
ID="ListBox1"
runat="server"
AutoPostBack="true"
OnSelectedIndexChanged="ListBox1_SelectedIndexChanged"
BackColor="DarkCyan"
ForeColor="AliceBlue"
>
<asp:ListItem>LawnGreen</asp:ListItem>
<asp:ListItem>LightSalmon</asp:ListItem>
<asp:ListItem>MediumBlue</asp:ListItem>
<asp:ListItem>MediumOrchid</asp:ListItem>
<asp:ListItem>Lavender</asp:ListItem>
</asp:ListBox>
</div>
</form>
</body>
</html>
