简单的送分问题！在线等！

Question

RadioButtonList List;
            if (i <= 25)
            {
                List = (RadioButtonList)Panel1.FindControl("rbtnList"+i.ToString());
            }
为什么List的值一直是null呢？

Answer 1

說明你的Panel中沒有rbtnList+i這個控件

Answer 2

     if (i  <= 25) 
            { 
                List = (RadioButtonList)Panel1.FindControl("rbtnList"+i.ToString()); 
            } 
呵呵。。i的值是0啊。。怎么可能会有值。。应该用个for循环。。

Answer 3

list没有实例
当然是null了

Answer 4

List 是系统已定义类名或关键字
FindControl方法没有找到控件

Answer 5

RadioButtonList List;
for (i=0;i <= 25;i++)
{
List = (RadioButtonList)Panel1.FindControl("rbtnList"+i.ToString());
//CODE:对List的操作
}

Answer 6

  for (int i = 1; i <= 50; i++)
        {
            RadioButtonList List;
            if (i <= 25)
            {
                List = (RadioButtonList)Panel1.FindControl("rbtnList"+i.ToString());
            }
完整的是这样的

Answer 7

以前有人讨论过这个问题，我试了一下代码，可行，发给你，你自己看看吧using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {
        TextBox txt=new TextBox();
        this.form1.Controls.Add(txt);        //
        createContros();
    }    Control cont = new Control();
    private void createContros()
    {
//------------------------------------
        for (int i = 0; i < 10; i++)
        {
            cont.Controls.Add(new LiteralControl("<tr>"));
            cont.Controls.Add(new LiteralControl("    <td align=\"center\" bgcolor=\"#EFEFEF\"><strong>"));            DateTime dt = DateTime.Now;
            dt = dt.AddDays(i);
            Label lable = new Label();
            lable.ID = "lable" + i;
            lable.Text = "第&nbsp;&nbsp;" + dt.Day  + "&nbsp;&nbsp;天";
            cont.Controls.Add(lable);            cont.Controls.Add(new LiteralControl("        </strong>"));
            cont.Controls.Add(new LiteralControl("    </td>"));
            cont.Controls.Add(new LiteralControl("    <td bgcolor=\"#EFEFEF\">&nbsp;&nbsp;&nbsp;&nbsp;<font color=\"red\">"));            Label lableTime = new Label();
            lableTime.ID = "lableTime" + i;
            lableTime.Text = Convert.ToString(dt.Year) + "年" + Convert.ToString(dt.Month) + "月" + Convert.ToString(dt.Day) + "日";
            cont.Controls.Add(lableTime);            cont.Controls.Add(new LiteralControl("    </font></td>"));
            cont.Controls.Add(new LiteralControl("    <td align=\"center\" bgcolor=\"#EFEFEF\">用&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;餐：</td>"));
            cont.Controls.Add(new LiteralControl("    <td bgcolor=\"#EFEFEF\">"));            CheckBoxList check = new CheckBoxList();
            check.ID = "check" + i;
            check.Items.Add(new ListItem("早餐", "早餐"));
            check.Items.Add(new ListItem("中餐", "中餐"));
            check.Items.Add(new ListItem("晚餐", "晚餐"));
            check.RepeatDirection = RepeatDirection.Horizontal;
            cont.Controls.Add(check);            cont.Controls.Add(new LiteralControl("    </td>"));
            cont.Controls.Add(new LiteralControl("    <td align=\"center\" bgcolor=\"#EFEFEF\">入&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;住：</td>"));
            cont.Controls.Add(new LiteralControl("    <td bgcolor=\"#EFEFEF\">"));            TextBox txt = new TextBox();
            txt.ID = "txtRZ" + i;
            cont.Controls.Add(txt);            cont.Controls.Add(new LiteralControl("    </td>"));
            cont.Controls.Add(new LiteralControl("</tr>"));
            cont.Controls.Add(new LiteralControl("<tr>"));
            cont.Controls.Add(new LiteralControl("    <td colspan=\"6\" align=\"center\" height=\"5\">"));
            cont.Controls.Add(new LiteralControl("    </td>"));
            cont.Controls.Add(new LiteralControl("</tr>"));
            cont.Controls.Add(new LiteralControl("<tr>"));
            cont.Controls.Add(new LiteralControl("    <td align=\"center\">简&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;介："));
            cont.Controls.Add(new LiteralControl("    <td colspan=\"5\">"));            TextBox content = new TextBox();
            content.ID = "txtJJ" + i;
            content.Rows = 4;
            content.TextMode = TextBoxMode.MultiLine;
            content.Width = Unit.Parse("300px");
            cont.Controls.Add(content);            cont.Controls.Add(new LiteralControl("    </td>"));
            cont.Controls.Add(new LiteralControl("</tr>"));
            cont.Controls.Add(new LiteralControl(" <tr>"));
            cont.Controls.Add(new LiteralControl("    <td colspan=\"6\" align=\"center\" height=\"5\">"));
            cont.Controls.Add(new LiteralControl("    </td>"));
            cont.Controls.Add(new LiteralControl("</tr>"));
        }
        form1.Controls.Add(cont);
    }    protected void Button1_Click(object sender, EventArgs e)
    {
        //MessageClass mc = new MessageClass();
        //mc.Silent = true;
        //mc.Charset = "gb2312";
        //mc.ISOEncodeHeaders = false;
        //mc.Subject = this.txtTitle.Text;
        string content = "";
        content += "<table width=\"780\" border=\"0\" align=\"center\" cellpadding=\"0\" cellspacing=\"0\" class=\"bd\">";//-----------------------------------------------------------------------
        for (int i = 0; i < 10; i++)
        {
            DateTime dt = DateTime.Now;
            dt = dt.AddDays(i);            CheckBoxList check = (CheckBoxList)cont.FindControl("check" + i);            string checkText = "";
            for (int j = 0; j < 3; j++)
            {
                if (check.Items[j].Selected)
                {
                    checkText += check.Items[j].Value + "、";
                }
            }
            if (checkText != "")
            {
               // checkText = checkText.Substring(checkText.IndexOf("、"));
            }            content += "    </tr>";
            content += "        <td align=\"center\" bgcolor=\"#EFEFEF\"><strong>第&nbsp;&nbsp;" + dt.Day + "&nbsp;&nbsp;天</strong></td>";
            content += "        <td bgcolor=\"#EFEFEF\">&nbsp;&nbsp;&nbsp;&nbsp;<font color=\"red\">" + Convert.ToString(dt.Year) + "年" + Convert.ToString(dt.Month) + "月" + Convert.ToString(dt.Day) + "日</font></td>";
            content += "        <td align=\"center\" bgcolor=\"#EFEFEF\">用&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;餐：</td>";
            content += "        <td bgcolor=\"#EFEFEF\">" + checkText + "</td>";
            content += "        <td align=\"center\" bgcolor=\"#EFEFEF\">入&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;住：</td>";
            content += "        <td bgcolor=\"#EFEFEF\">" + "aaaaaaaaaa" + "</td>";
            content += "    </tr>";
            content += "    <tr>";
            content += "        <td colspan=\"6\" align=\"center\" height=\"5\">";
            content += "        </td>";
            content += "    </tr>";
            content += "    <tr>";
            content += "        <td align=\"center\">简&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;介：";
            content += "        <td colspan=\"5\">" + "aaaaaaaaaaa" + "</td>";
            content += "    </tr>";
            content += "    <tr>";
            content += "        <td colspan=\"6\" align=\"center\" height=\"5\">";
            content += "        </td>";
            content += "    </tr>";
        }        Response.Write(content);
        //mc.HTMLBody = content;
        //mc.From = myconfig.mailFrom;
        //mc.FromName = "BETRIP";
        //mc.MailServerUserName = myconfig.mailFrom;
        //mc.MailServerPassWord = myconfig.mailPass;
        //mc.ContentType = "text/html";
        //mc.AddRecipient(myconfig.mailReceiving, "", "");        //bool res = mc.Send(myconfig.mailServer, false);
        //mc.Clear();
        //mc.Close();
        //mc = null;
        //linTool.showError("回复成功!", "order.aspx");
    }
}