dougv.net « Doug Vanderweide's ASP.NET demos

How to move a ListItem from a DropDownList / ComboBox control to a ListBox control. This code removes selected items from the DropDownList / ComboBox as they are added to the ListBox.

Page Code

            <asp:DropDownList runat="server" ID="cbxCountries" AutoPostBack="true">
                <asp:ListItem Text="Select ..." Value="" />
                <asp:ListItem Value="USA" />
                <asp:ListItem Value="Canada" />
                <asp:ListItem Value="Mexico" />
                <asp:ListItem Value="Guatemala" />
                <asp:ListItem Value="Belize" />
                <asp:ListItem Value="El Salvador" />
                <asp:ListItem Value="Honduras" />
                <asp:ListItem Value="Nicaragua" />
                <asp:ListItem Value="Costa Rica" />
                <asp:ListItem Value="Panama" />
            </asp:DropDownList>
            
            <asp:ListBox runat="server" ID="lstCountries" Rows="10" />
        

Code Behind

            Sub cbxCountries_selectedIndexChanged(ByVal Sender As Object, ByVal E As EventArgs) Handles cbxCountries.SelectedIndexChanged
	            If Not String.IsNullOrEmpty(cbxCountries.SelectedValue) Then
		            'reset selected index for listbox; this is required for adding new listitems
		            lstCountries.SelectedIndex = -1

		            'ASP.NET version: add selected listitem to listbox
		            Dim lsiSelected As ListItem = cbxCountries.Items(cbxCountries.SelectedIndex)

		            'Windows Forms version: add selected listitem to listbox
		            'Dim lsiSelected As Object = cbxCountries.Items(cbxCountries.SelectedIndex)

		            lstCountries.Items.Add(lsiSelected)

		            'remove selected from combobox
		            cbxCountries.Items.RemoveAt(cbxCountries.SelectedIndex)
	            End If
            End Sub