How to: Add Items in List Web Server Controls

项目
10/15/2014

The information in this topic applies to all list Web server controls: ListBox, DropDownList, CheckBoxList, RadioButtonList, and BulletedList. You can add items to a list Web server control in these ways:

Add static items at design time.
Add items programmatically at run time.
Add items using data binding. For details, see How to: Populate List Web Server Controls from a Data Source. You can add items from a data source to static items you create at design time.

When you add a list item, you specify up to three possible properties of the item, as described in the following table.

Property	Description
Text	The text displayed in the list.
Value	The value associated with an item. Setting this property allows you to associate a value with a specific item without displaying it. For example, you can set the Text property to the name of a color and the Value property to the HTML value for that color.
Selected	A Boolean value indicating whether the item is selected. In a CheckBoxList control or a multi-selection ListBox control, more than one item can be selected. In a DropDownList control, a RadioButtonList control, or a single-selection ListBox control, only one item can be selected at a time. If you set more than one selected item in these controls, the browser determines which item is rendered as selected.

To add static items at design time

Type an <asp:ListItem> element into the page as a child of the list control. For syntax, see ListBox Web Server Control.
Set the Text and Value properties of the new list item.
Optionally, set the Selected property for one or more items. (Note that certain controls allow only one item to be selected.)

Repeat steps 1 through 3 for each item to add.

The following code example shows a ListBox control with three statically defined items.

<asp:ListBox ID="ListBox1" runat="server">
    <asp:ListItem Text="Red" Value="#FF0000" Selected="True" />
    <asp:ListItem Text="Blue" Value="#0000FF" />
    <asp:ListItem Text="Green" Value="#008000" />
</asp:ListBox><br />

To add items programmatically

Create a new object of type ListItem and set its Text and Value properties.

Call the Add method of the control's Items collection and pass it the new object.

The following code example shows how to add ListItem objects to a ListBox control, but the procedure is identical for all list Web server controls.

Protected Sub Button1_Click(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles Button1.Click
    ListBox1.Items.Add(New ListItem("Carbon", "C"))
    ListBox1.Items.Add(New ListItem("Oxygen", "O"))
End Sub

Protected void Button1_Click (object sender, System.EventArgs e)
{
    ListBox1.Items.Add(new ListItem("Carbon", "C"));
    ListBox1.Items.Add(new ListItem("Oxygen", "O"));
}

通过

How to: Add Items in List Web Server Controls

To add static items at design time

To add items programmatically

See Also

Reference

Concepts

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