Struts中类型转换报错

问题描述

今天遇到一个非常郁闷的问题,先看下面代码 这个是JSP页面取值代码:            <td width="102" height="30" align="left"><bean:write name="regediter" property="username"/></td>             <td width="81" align="left"><bean:write name="regediter" property="password"/></td>            <td width="76" align="left"><bean:write name="regediter" property="msn"/></td>            <td width="68" align="left"><bean:write name="regediter" property="qq"/></td> 这个是Action 处理请求代码:  public ActionForward execute(ActionMapping mapping, ActionForm form,   HttpServletRequest request, HttpServletResponse response) {  int current = 0 ;  String id = request.getParameter("id");  List list ;  if(id==null){   list = HibernateDbConnection.getInstance().findById();  }else{   list = HibernateDbConnection.getInstance().findById(Integer.valueOf(id));  }  Regediter regediter = (Regediter)list;  request.setAttribute("list", regediter);  request.setAttribute("current", current);  return mapping.findForward("success"); 这个是异常信息:avax.servlet.ServletException: java.lang.ClassCastException: java.util.ArrayList cannot be cast to customs.zheng.Web.Regediter 我标记的红色字体是错误的关键,寻求解决办法

解决方案

引用Regediter regediter = (Regediter)list;这样写肯定不对嘛！怎么能吧list 转换成一个 Regediter 对象呢？如果是一个对象的话（因为你是 findbyId） Regediter regediter = (Regediter)list.get(0); OK 了 试试
解决方案二：
Regediter regediter = (Regediter)list.get(0);