How to: Set the Selection in List Web Server Controls
The information in this topic applies to all list Web server controls:, , , and .
Normally, users select items in a list Web server control to indicate a choice. However, you might want to preselect items or select items at run time (programmatically) based on some condition.
To set the selection in a list Web server control at design time
Set theproperty of the list item to true. If the control supports multiple selection, you can set Selected property for each item to be selected.
The following code example shows how to select the first item in a ListBox control.
<asp:ListBox ID="ListBox1" runat="server"> <asp:ListItem Selected="True">A</asp:ListItem> <asp:ListItem>B</asp:ListItem> <asp:ListItem>C</asp:ListItem> </asp:ListBox> </div>
To set a single selection in a list Web server control programmatically
Set the control'sproperty to the index value of the item to select. The index is zero-based. To set no selection, set SelectedIndex to -1.
To set multiple selections in a list control programmatically
Loop through the control'scollection and set the Selected property of every individual item.
You can select multiple items only if the control's SelectionMode property is set to Multiple.
The following code example shows how you can set selections in a multi-selection ListBox control called ListBox1. The code selects every other item.
Protected Sub Button1_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles Button1.Click Dim i As Integer Dim li As ListItem For Each li In ListBox1.Items i += 1 If (i Mod 2 = 0) Then li.Selected = True End If Next End Sub