ASP.NET ASP.NET - Basic Controls List Controls
Example
ASP.NET provides the following controls
- Drop-down list
- List box
- Radio button list
- Check box list
- Bulleted list
These control let a user choose from one or more items from the list. List boxes and drop-down lists contain one or more list items. These lists can be loaded either by code or by the ListItemCollection editor.
Basic syntax of list box control:
<asp:ListBox ID="ListBox1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ListBox1_SelectedIndexChanged">
</asp:ListBox>
Basic syntax of drop-down list control:
<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
</asp:DropDownList>
Common properties of list box and drop-down Lists:
| Properties | Description |
|---|---|
| Items | The collection of ListItem objects that represents the items in the control. This property returns an object of type ListItemCollection. |
| Rows | Specifies the number of items displayed in the box. If actual list contains more rows than displayed then a scroll bar is added. |
| SelectedIndex | The index of the currently selected item. If more than one item is selected, then the index of the first selected item. If no item is selected, the value of this property is -1. |
| SelectedValue | The value of the currently selected item. If more than one item is selected, then the value of the first selected item. If no item is selected, the value of this property is an empty string (""). |
| SelectionMode | Indicates whether a list box allows single selections or multiple selections. |
Common properties of each list item objects:
| Properties | Description |
|---|---|
| Text | The text displayed for the item. |
| Selected | A string value associated with the item. |
| Value | Indicates whether the item is selected. |
It is important to notes that:
- To work with the items in a drop-down list or list box, you use the Items property of the control. This property returns a ListItemCollection object which contains all the items of the list.
- The SelectedIndexChanged event is raised when the user selects a different item from a drop-down list or list box.
