Question

这个是什么错误啊

type Exception report
message An exception occurred processing JSP page /manage/exercise/video_edit.jsp at line 43 40: <option value="-1">--璇烽�鎷�-</option> 41: <% 42: List<Category> list = (List<Category>) request.getAttribute("list"); 43: for (Category category : list) { 44: %> 45: <option value="<%=category.getCategoryid()%>"<%if(video.getCategoryid()==category.getCategoryid()){ %>selected<%} %> > 46: <%=category.getName()%></option> Stacktrace:
description The server encountered an internal error (An exception occurred processing JSP page /manage/exercise/video_edit.jsp at line 43 40: <option value="-1">--璇烽�鎷�-</option> 41: <% 42: List<Category> list = (List<Category>) request.getAttribute("list"); 43: for (Category category : list) { 44: %> 45: <option value="<%=category.getCategoryid()%>"<%if(video.getCategoryid()==category.getCategoryid()){ %>selected<%} %> > 46: <%=category.getName()%></option> Stacktrace:) that prevented it from fulfilling this request.
exception

Answer 1

这是错误吗？

Answer 2

怀疑是JSP容器版本问题。你先试着简单修改一下：
<%
List<Category> list = (List<Category>) request.getAttribute("list");
if(list==null) System.out.println("list == null!!!"); //此处简单判断一下是否为空，虽然不正规，做测试用足够了
for(int i=0; i<list.size(); i++){ //此处for循环不使用Category category : list方式，测试是否是版本问题造成的
Category category = list.get(i);
%>

测试完看看结果怎样。