Introduction
Dropdownlist is a string collection control class. Through the ListItem class, we can add some string into it. If we add some item into it in the code file only one string can add in it. Like
Dropdownlist1.items.add(String item);
But at the compile/Design time, we can add text as well as value in it. At the compile time, visual Studio IDE use ListItem class for data insertion. ListItem class provide overloaded constructor, Through this we can add both Text and Value.
Example:
Source code of the file : Complete Code Download
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default5.aspx.cs" Inherits="Default5" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<asp:DropDownList ID="DropDownList1" runat="server"></asp:DropDownList>
<p>
<asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_Click" />
</p>
<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
</form>
</body>
</html>
Code Behind file
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class Default5 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if(!Page.IsPostBack)
{
DropDownList1.Items.Add(new ListItem("Apple", "20"));
DropDownList1.Items.Add(new ListItem("Mango", "30"));
DropDownList1.Items.Add(new ListItem("Grapes", "40"));
}
}
protected void Button1_Click(object sender, EventArgs e)
{
Label1.Text = DropDownList1.SelectedValue;
}
}
Code Generate the following output
In this example, we have three control on design. First to add Text with value in the DropdownList using the ListItem class. Now, On button click, we accessed the selected item value of control in the label.
