$_$ 为什么每次DropDownList.AutoPostBack返回值都是一样,请高手指点

[cool_jack2006]

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
DropDownList1.AutoPostBack = true;
}
ArrayList address = new ArrayList();
address.Add("美国");
address.Add("中国");
address.Add("日本");
DropDownList1.DataSource = address;
DropDownList1.DataBind();
}
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
switch(DropDownList1.SelectedValue)
{
case "中国":
{
ArrayList china_address = new ArrayList();
china_address.Add("湖南");
china_address.Add("广东");
china_address.Add("广西");
DropDownList2.DataSource = china_address;
DropDownList2.DataBind();
break;
}
case "美国":
{
ArrayList american_address = new ArrayList();
american_address.Add("洛杉矶");
american_address.Add("圣安德列斯");
DropDownList2.DataSource = american_address;
DropDownList2.DataBind();
break;
}
case "日本":
{
ArrayList japan_address = new ArrayList();
japan_address.Add("神户");
japan_address.Add("大板");
DropDownList2.DataSource = japan_address;
DropDownList2.DataBind();
break;
}
}
}

[tangjunping]

你将你的
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
DropDownList1.AutoPostBack = true;
}
ArrayList address = new ArrayList();
address.Add("美国");
address.Add("中国");
address.Add("日本");
DropDownList1.DataSource = address;
DropDownList1.DataBind();
}
代码改为
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
DropDownList1.AutoPostBack = true;
ArrayList address = new ArrayList();
address.Add("美国");
address.Add("中国");
address.Add("日本");
DropDownList1.DataSource = address;
DropDownList1.DataBind();
}
}
就可以得到你想要的结果了

[tangjunping]

至于原因，我想你看了代码也就明白了吧

[银狐被占用]

1楼正解。
页面重新对下拉框进行添加了。