java.lang.ClassCastException: java.lang.String问题,请高手解决

productlist.jsp代码:
<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<%@ page import="java.util.*" %>
<%@ page import="com.hzm.shoppcat.dao.*" %>
<%@  taglib uri="http://struts.apache.org/tags-logic" prefix="logic"%>
<%@  taglib uri="http://struts.apache.org/tags-bean" prefix="bean"%><%@ taglib uri="/WEB-INF/struts-html.tld" prefix="s"%>    
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>Insert title here</title>
</head>
    <body>
     <table>
     <tr>
     <td></td>
     <td></td>
     </tr>
     <%
     List<CartProduct> list=null;
     list = (List<CartProduct>)request.getSession().getAttribute("list");
CartProduct product = new CartProduct();
     if(list==null||list.size()==0){
      %>
       <tr>
       <td></td>
       </tr>
       <%}else{ %>
       <tr>
       <td>
      
       </td>
       <%for(Iterator iter =list.iterator();iter.hasNext();){ 
       product = (CartProduct)iter.next();//在这里报错了
       %>
       <td>
       <%=product.getName() %>
       </td>       <%
       }
       } 
       %>
       </tr>
     </table>
    </body>
</html>异常信息:
exception org.apache.jasper.JasperException: java.lang.String
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:358)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1085)
org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:398)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:241)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
javax.servlet.http.HttpServlet.service(HttpServlet.java:743)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
root cause java.lang.ClassCastException: java.lang.String
org.apache.jsp.productlist_jsp._jspService(productlist_jsp.java:61)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:133)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:311)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1085)
org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:398)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:241)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
javax.servlet.http.HttpServlet.service(HttpServlet.java:743)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)请问如何解决