内容纲要
ASP.NET Web Forms ArrayList 对象是包含单个数据值的项目的集合
范例
- ArrayList DropDownList
<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()
dd.DataSource=mycountries
dd.DataBind()
end if
end sub
sub displayMessage(s as Object,e As EventArgs)
lbl1.text="Your favorite country is: " & dd.SelectedItem.Text
end sub
</script>
<!DOCTYPE html>
<meta charset="utf-8" />
<form runat="server">
<asp:DropDownList id="dd" runat="server"
AutoPostBack="True" onSelectedIndexChanged="displayMessage" />
<p><asp:label id="lbl1" runat="server" /></p>
</form>
- ArrayList RadioButtonList
<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
sub displayMessage(s as Object,e As EventArgs)
lbl1.text="Your favorite country is: " & rb.SelectedItem.Text
end sub
</script>
<!DOCTYPE html>
<meta charset="utf-8" />
<form runat="server">
<asp:RadioButtonList id="rb" runat="server"
AutoPostBack="True" onSelectedIndexChanged="displayMessage" />
<p><asp:label id="lbl1" runat="server" /></p>
</form>
创建 ArrayList
ArrayList 对象是包含单个数据值的项目的集合
通过 Add() 方法向 ArrayList 添加项目
下面的代码创建了一个名为 mycountries 的 ArrayList 对象，并添加了四个项目
<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>
在默认情况下，一个 ArrayList 对象包含 16 个条目
可通过 TrimToSize() 方法把 ArrayList 调整为最终尺寸
<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>
通过 Sort() 方法，ArrayList 也能够按照字母顺序或者数字顺序进行排序
<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>
要实现反向排序，请在 Sort() 方法后应用 Reverse() 方法
<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>
绑定数据到 ArrayList
ArrayList 对象可为下列的控件自动生成文本和值
- asp:RadioButtonList
- asp:CheckBoxList
- asp:DropDownList
- asp:Listbox
为了绑定数据到 RadioButtonList 控件，首先要在 .aspx 页面中创建一个 RadioButtonList 控件（不带任何 asp:ListItem 元素）
<!DOCTYPE html>
<meta charset="utf-8" />
<form runat="server">
<asp:RadioButtonList id="rb" runat="server" />
</form>
然后添加创建列表的脚本，并且绑定列表中的值到 RadioButtonList 控件
<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>
<!DOCTYPE html>
<meta charset="utf-8" />
<form runat="server">
<asp:RadioButtonList id="rb" runat="server" />
</form>
RadioButtonList 控件的 DataSource 属性被设置为该 ArrayList，它定义了这个 RadioButtonList 控件的数据源
RadioButtonList 控件的 DataBind() 方法把 RadioButtonList 控件与数据源绑定在一起
数据值作为控件的 Text 和 Value 属性来使用
如需添加不同于 Text 的 Value，请使用 Hashtable 对象或者 SortedList 对象
