Hi Waghmare,
Refer the Below Sample for your reference.
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<link rel="stylesheet" type="text/css" href="http://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.0.3/css/bootstrap.min.css" />
<script type="text/javascript" src="http://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.0.3/js/bootstrap.min.js"></script>
<link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.5.4/bootstrap-select.css" />
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.5.4/bootstrap-select.js"></script>
<script type="text/javascript">
$(function () {
$('#ddlFruits').selectpicker({
style: 'btn-info',
size: 4
});
});
</script>
</head>
<body>
<form id="form1" runat="server">
<div class="row">
<div class="col-md-2">
<asp:DropDownList ID="ddlFruits" runat="server">
<asp:ListItem Text="Please Select" Value="0"></asp:ListItem>
<asp:ListItem Text="Mango" Value="1" />
<asp:ListItem Text="Apple" Value="2" />
<asp:ListItem Text="Banana" Value="3" />
<asp:ListItem Text="Guava" Value="4" />
<asp:ListItem Text="Orange" Value="5" />
</asp:DropDownList>
</div>
<div class="col-md-2">
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" ControlToValidate="ddlFruits"
runat="server" InitialValue="0" ErrorMessage="Required"></asp:RequiredFieldValidator>
</div>
<div class="col-md-2">
<asp:Button ID="Button1" Text="Submit" runat="server" OnClick="Submit" class="btn btn-primary" />
</div>
</div>
</form>
</body>
</html>
C#
protected void Submit(object sender, EventArgs e)
{
string selectedvalue = string.Format("Selected Value: {0} and Selected Text: {1}", ddlFruits.SelectedValue, ddlFruits.SelectedItem.Text);
ClientScript.RegisterClientScriptBlock(this.GetType(), "", "alert('" + selectedvalue + "')", true);
}
VB.Net
Protected Sub Submit(sender As Object, e As EventArgs)
Dim selectedvalue As String = String.Format("Selected Value: {0} and Selected Text: {1}", ddlFruits.SelectedValue, ddlFruits.SelectedItem.Text)
ClientScript.RegisterClientScriptBlock(Me.[GetType](), "", (Convert.ToString("alert('") & selectedvalue) + "')", True)
End Sub
Screeshot
