ASP.NET ArrayList

From http://www.w3schools.com (Copyright Refsnes Data)

# ASP.NET - The ArrayList Object

The ArrayList object is a collection of items containing a single data value.

## Examples

Example 1 - ArrayList RadioButtonList

Example 2 - ArrayList DropDownList

## Create an ArrayList

The ArrayList object is a collection of items containing a single data value.

Items are added to the ArrayList with the Add() method.

The following code creates a new ArrayList object named mycountries and four items are added:

    <script runat="server">
    Sub Page_Load
    if Not Page.IsPostBack then
      dim mycountries=New ArrayList
      mycountries.Add("Norway")
      mycountries.Add("Sweden")
      mycountries.Add("France")
      mycountries.Add("Italy")
    end if
    end sub
    </script>

By default, an ArrayList object contains 16 entries. An ArrayList can be sized to its final size with the TrimToSize() method:

    <script runat="server">
    Sub Page_Load
    if Not Page.IsPostBack then
      dim mycountries=New ArrayList
      mycountries.Add("Norway")
      mycountries.Add("Sweden")
      mycountries.Add("France")
      mycountries.Add("Italy")
      mycountries.TrimToSize()
    end if
    end sub
    </script>

An ArrayList can also be sorted alphabetically or numerically with the Sort() method:

    <script runat="server">
    Sub Page_Load
    if Not Page.IsPostBack then
      dim mycountries=New ArrayList
      mycountries.Add("Norway")
      mycountries.Add("Sweden")
      mycountries.Add("France")
      mycountries.Add("Italy")
      mycountries.TrimToSize()
      mycountries.Sort()
    end if
    end sub
    </script>

To sort in reverse order, apply the Reverse() method after the Sort() method:

    <script runat="server">
    Sub Page_Load
    if Not Page.IsPostBack then
      dim mycountries=New ArrayList
      mycountries.Add("Norway")
      mycountries.Add("Sweden")
      mycountries.Add("France")
      mycountries.Add("Italy")
      mycountries.TrimToSize()
      mycountries.Sort()
      mycountries.Reverse()
    end if
    end sub
    </script>

## Data Binding to an ArrayList

An ArrayList 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" />
    </form>

    </body>
    </html>

Then add the script that builds the list and binds the values in the list to the RadioButtonList control:

    <script runat="server">
    Sub Page_Load
    if Not Page.IsPostBack then
      dim mycountries=New ArrayList
      mycountries.Add("Norway")
      mycountries.Add("Sweden")
      mycountries.Add("France")
      mycountries.Add("Italy")
      mycountries.TrimToSize()
      mycountries.Sort()
      rb.DataSource=mycountries
      rb.DataBind()
    end if
    end sub
    </script>

    <html>
    <body>

    <form runat="server">
    <asp:RadioButtonList id="rb" runat="server" />
    </form>

    </body>
    </html>

The DataSource property of the RadioButtonList control is set to the ArrayList and it defines the data source of the RadioButtonList control. The DataBind() method of the RadioButtonList control binds the data source with the RadioButtonList control.

Note: The data values are used as both the Text and Value properties for the control. To add Values that are different from the Text, use either the Hashtable object or the SortedList object.

From http://www.w3schools.com (Copyright Refsnes Data)