大家帮我看下怎么样用循环怎输入这个信息。

DAO层代码：
public Map<String, Object> getinfo(String tid)
{
Map<String, Object> map=new HashMap<String, Object>();
String sql="select * from daytopics where tid="+tid;
Result rstResult=excuteQuery(sql,null);
for(int i=0;i<rstResult.getRowCount();i++){
Map row = rstResult.getRows()[i];
map.put("DayTopic", inittopic(row));
}

sql="select * from topictalk where tid="+tid;
Result rst=excuteQuery(sql,null);
for(int i=0;i<rst.getRowCount();i++){
Map r = rst.getRows()[i];
map.put("TopticTalk", initTalk(r));
}
return map;
}


servlet代码：

request.setCharacterEncoding("utf-8");
String op=request.getParameter("op");
String tid=request.getParameter("Tid");
String url="";
if(op.equalsIgnoreCase("show_Topic")){
Map<String, Object> map=new DayTopicDao().getinfo(tid);
//if(map.containsKey("1"))
//{
DayTopic da=(DayTopic )map.get("DayTopic");
//}else if (map.containsKey("2")) {
TopticTalk dt=(TopticTalk)map.get("TopticTalk");
//}
request.setAttribute("topic",da);
request.setAttribute("topictalk",dt);
url="/show_Topic.jsp";
}
request.getRequestDispatcher(url).forward(request, response);


JSP页面代码：

<c:set var="talk" scope="page" value="${requestScope.topictalk}"></c:set>
<tr>
<td width="100" height="50" align="center" style="border-bottom: dashed #B5B9CA 1px;"><img src="images/char.gif" style="border:#cccccc 1px solid;"/><br />
<br />
${talk.Comauthor}</td>
<td align="left" class="top01" style="border-bottom: dashed #B5B9CA 1px;">${talk.tpcomment }<br />
<span style="font-size:11px;color:#999999;height:30px;line-height:30px;">${talk.tptime }</span>
</td>
</tr>
<tr>
我一用forEach循环就报错，报错信息为：javax.servlet.jsp.JspTagException: Don't know how to iterate over supplied "items" in <forEach>
请教各位我怎么样才能循环输出啊，求具体代码，本人菜鸟哦，勿笑啊