Populate items in DropDownList from TextBox Value in ASP.Net

This way

 <asp:TextBox ID="txtFruit" runat="server" />
    <asp:Button ID="btnAdd" runat="server" Text="Add Item" OnClick="AddItem" />
    <br />
    <asp:DropDownList ID="ddlFruits" runat="server">
        <asp:ListItem Text="----Fruits----" Value=""></asp:ListItem>
    </asp:DropDownList>

 protected void AddItem(object sender, EventArgs e)
    {
        string fruit = txtFruit.Text.Trim();
        if (!string.IsNullOrEmpty(fruit))
        {
            ddlFruits.Items.Add(new ListItem(fruit, fruit));
        }
    }