public ActionForward delete(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response) {
       manager.delete(request.getParameter("id"));
       return list(mapping,form,request,response);
}/////////////////////////////////////////////
/public ActionForward delete(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response) {
       manager.delete(request.getParameter("id"));
       return list(mapping,form,request,response);
}
 attempt to create delete event with null entity????????????????????会有这样的错误?