ASP.NET Web Forms - The SortedList Object
The SortedList object combines the features of both the ArrayList object and the Hashtable object.
Examples
The SortedList Object
The SortedList object contains items in key/value pairs.
A SortedList object automatically sorts the items in alphabetic or numeric order.
Items are added to the SortedList with the Add() method.
A SortedList can be sized to its final size with the TrimToSize() method.
The following code creates a SortedList named mycountries and four elements are added:
<script runat="server">
sub Page_Load
if Not Page.IsPostBack then
dim mycountries=New SortedList
mycountries.Add("N","Norway")
mycountries.Add("S","Sweden")
mycountries.Add("F","France")
mycountries.Add("I","Italy")
end if
end sub
</script>
Data Binding
A SortedList object may automatically generate the text and values to the following controls:
- asp:RadioButtonList
- asp:CheckBoxList
- asp:DropDownList
- asp:Listbox
To bind data to a RadioButtonList control, first create a RadioButtonList control (without any asp:ListItem elements) in an .aspx page:
<html>
<body>
<form runat="server">
<asp:RadioButtonList id="rb" runat="server"
AutoPostBack="True" />
</form>
</body>
</html>
Then add the script that builds the list:
<script runat="server">
sub Page_Load
if Not Page.IsPostBack then
dim mycountries=New SortedList
mycountries.Add("N","Norway")
mycountries.Add("S","Sweden")
mycountries.Add("F","France")
mycountries.Add("I","Italy")
rb.DataSource=mycountries
rb.DataValueField="Key"
rb.DataTextField="Value"
rb.DataBind()
end if
end sub
</script>
<html>
<body>
<form runat="server">
<asp:RadioButtonList id="rb" runat="server"
AutoPostBack="True" />
</form>
</body>
</html>
Then we add a sub routine to be executed when the user clicks on an item in the RadioButtonList control. When a radio button is clicked, a text will appear in a label:
Example
<script runat="server">
sub Page_Load
if Not Page.IsPostBack then
dim mycountries=New SortedList
mycountries.Add("N","Norway")
mycountries.Add("S","Sweden")
mycountries.Add("F","France")
mycountries.Add("I","Italy")
rb.DataSource=mycountries
rb.DataValueField="Key"
rb.DataTextField="Value"
rb.DataBind()
end if
end sub
sub displayMessage(s as Object,e As EventArgs)
lbl1.text="Your favorite country is: " & rb.SelectedItem.Text
end sub
</script>
<html>
<body>
<form runat="server">
<asp:RadioButtonList id="rb" runat="server"
AutoPostBack="True" onSelectedIndexChanged="displayMessage" />
<p><asp:label id="lbl1" runat="server" /></p>
</form>
</body>
</html>
Show example »
