asp.net - How to remove all items from a DropDownList

DropDownList.Items.Clear() Method

asp.net dropdownlist web server control allow us to render a single selection drop-down-list control in web browser. each items in dropdownlist control represent a ListItem object. a ListItemCollection object store all ListItem objects within a dropdownlist.

so we can add or remove items from dropdownlist control by adding or removing item from this list item collection object. ListItemCollection class Clear method removes (delete) all items (ListItem objects) from the items collection. we cannot undo the method and it also set the Count property value zero.

the following c# example source code demonstrate us how can we remove (clear, delete) all list items from dropdownlist server control programmatically at run time in asp.net.

DropDownListClear.aspx


<%@ Page Language="C#" %>

<!DOCTYPE html>

<script runat="server">
    protected void Button1_Click(object sender, System.EventArgs e)
    {
        DropDownList1.Items.Clear();
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>How to remove all items from DropDownList, items clear</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <h2 style="color:Navy">DropDownList: Items Clear</h2>
        <asp:Label 
             ID="Label1"
             runat="server"
             Font-Bold="true"
             ForeColor="SeaGreen"
             Text="asp.net controls"
             >
        </asp:Label>
        <asp:DropDownList 
             ID="DropDownList1"
             runat="server"
             >
             <asp:ListItem>ListBox</asp:ListItem>
             <asp:ListItem>RadioButtonList</asp:ListItem>
             <asp:ListItem>SqlDataSource</asp:ListItem>
             <asp:ListItem>SiteMapDataSource</asp:ListItem>
             <asp:ListItem>RegularExpressionValidator</asp:ListItem>
        </asp:DropDownList>
        <br /><br />
        <asp:Button 
             ID="Button1"
             runat="server"
             Font-Bold="true"
             ForeColor="SaddleBrown"
             Text="Clear DropDownList"
             OnClick="Button1_Click"
             />
    </div>
    </form>
</body>
</html>

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