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严重: Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
at org.apache.jsp.view.regist_005fclass_jsp._jspService(regist_005fclass_jsp.java:111)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:263)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:584)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:745)
if ("toTeacherList".equalsIgnoreCase(operName)) {
List<UserInfo> List_teacher = infoDao.getTeacherInfo();
for(int i=0;i<List_teacher.size();i++){
System.out.println(List_teacher.get(i));
}
request.setAttribute("List_teacher", List_teacher);
request.getRequestDispatcher("/view/regist_class.jsp").forward(request, response);
<%
List<UserInfo> teacherList = (List<UserInfo>)request.getAttribute("List_teacher");
%>
<select name="teacher">
<%
for (UserInfo info : teacherList) {
%>
<option value="<%=info.getUsername()%>"><%=info.getUsername()%></option>
<%
}
%>
</select>