SelectedIndexChanged event in RadioButtonList
RadioButtonList is an ASP.NET list web server control that provides a
single selection radio button group. RadioButtonList can be populated
statically or dynamically from a data source object. RadioButtonList contains
an item collection that holds ListItem objects. Each ListItem object
represents an item (radio button) in RadioButtonList control.
RadioButtonList OnSelectedIndexChanged method raises the SelectedIndexChanged event. This method allows us to provide a custom handler for the SelectedIndexChanged event.
RadioButtonList SelectedIndexChanged event occurs when the item selection changes between posts to the web server. This event works only when we set the RadioButtonList control's AutoPostBack property value to True. AutoPostBack property gets or sets a value indicating whether a postback to the server automatically occurs when the user changes the list selection.
So when the user changes the RadioButtonList item selection then the SelectedIndexChanged event occurs and the page automatically postback to the server. After the postback, we can display the user selection result immediately on the web page.
The following ASP.NET C# example code demonstrates to us how can we use the SelectedIndexChanged event in RadioButtonList web server control.
RadioButtonList OnSelectedIndexChanged method raises the SelectedIndexChanged event. This method allows us to provide a custom handler for the SelectedIndexChanged event.
RadioButtonList SelectedIndexChanged event occurs when the item selection changes between posts to the web server. This event works only when we set the RadioButtonList control's AutoPostBack property value to True. AutoPostBack property gets or sets a value indicating whether a postback to the server automatically occurs when the user changes the list selection.
So when the user changes the RadioButtonList item selection then the SelectedIndexChanged event occurs and the page automatically postback to the server. After the postback, we can display the user selection result immediately on the web page.
The following ASP.NET C# example code demonstrates to us how can we use the SelectedIndexChanged event in RadioButtonList web server control.
RadioButtonListOnSelectedIndexChanged.aspx
<%@ Page Language="C#" %>
<!DOCTYPE html>
<script runat="server">
protected void RadioButtonList1_SelectedIndexChanged(object sender, System.EventArgs e)
{
Label1.Text = "Your favorite: " + RadioButtonList1.SelectedItem.Text;
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>How to use OnSelectedIndexChanged event in RadioButtonList</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<h2 style="color:Maroon">RadioButtonList: OnSelectedIndexChanged</h2>
<asp:Label
ID="Label1"
runat="server"
Font-Bold="true"
ForeColor="Teal"
Font-Size="Large"
>
</asp:Label>
<br /><br />
<asp:Label
ID="Label2"
runat="server"
Font-Bold="true"
ForeColor="DodgerBlue"
Text="Color List"
>
</asp:Label>
<asp:RadioButtonList
ID="RadioButtonList1"
runat="server"
AutoPostBack="true"
OnSelectedIndexChanged="RadioButtonList1_SelectedIndexChanged"
BackColor="DodgerBlue"
ForeColor="AliceBlue"
>
<asp:ListItem>Cyan</asp:ListItem>
<asp:ListItem>DarkBlue</asp:ListItem>
<asp:ListItem>DarkGreen</asp:ListItem>
<asp:ListItem>DarkSalmon</asp:ListItem>
<asp:ListItem>Crimson</asp:ListItem>
</asp:RadioButtonList>
</div>
</form>
</body>
</html>
