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I can't get my code working, the only clue I got is the warning about unchecked cast, but it seems to me that I can't be more precise ....

I tried to put the @SuppressWarnings (value="unchecked") just above my code inside the <% %> but it didn't work...

Here is the error log : 

juin 22, 2016 4:25:34 AM org.apache.catalina.core.StandardWrapperValve invoke
GRAVE: Servlet.service() for servlet [GroupeEleve] in context with path [/GAPP2] threw exception [
An exception occurred processing JSP page /WEB-INF/view/profilEtudiant.jsp at line 668

665:     <tr>
666:     <% 
667:         Users U = (Users)session.getAttribute("user");
668:         Set<Absences> A=(Set<Absences>)U.getAbsenceses();
669          List<Absences> B = new ArrayList<Absences>(A);
670:         for(int i=0;i<B.size();i++){%>
671:             <td><%out.print(B.get(i).getDate()) ;%></td>


Stacktrace:] with root cause
java.lang.NullPointerException
    at org.apache.jsp.WEB_002dINF.view.profilEtudiant_jsp._jspService(profilEtudiant_jsp.java:817)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:439)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:747)
    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:485)
    at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:410)
    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:337)
    at com.isep.controlleurs.GroupeEleve.doGet(GroupeEleve.java:46)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:436)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1078)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Unknown Source)
BalusC
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Mayeul sgc
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  • Your `session` doesn't have an attribute named `user`. – Elliott Frisch Jun 22 '16 at 02:30
  • I don't understand, I have in anotherpart of my page a command `${sessionScope.sessionUser.name} ` which gives me the result but name is a `user ` Object Attribute ... – Mayeul sgc Jun 22 '16 at 02:42
  • `session.getAttribute("user")` returned `null`. That's why you get a NullPointerException at `Set A=(Set)U.getAbsenceses();` – Elliott Frisch Jun 22 '16 at 02:43
  • It was the name of the session attribute that wasn't right, thank you for your attention, it's been a while i've been looking for it ... – Mayeul sgc Jun 22 '16 at 03:02

1 Answers1

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May be your session doesn't have User attribute.Please check your session user.if User is not null,then it may be U.getAbsenceses() return null and Set A will get null value.So when you assign value from A to B and when you call B.get(i).getDate() will cause null pointer exception.

sawyinwaimon
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