javax.faces.el.EvaluationException: java.lang.NullPointerException in my jsf web App - jsf-2

Question

I am working on a dynamic Web Application and as a first step i want to use my jsf page to save a new Group in the DataBase .I am connecting to an Oracle 10g DataBase, working on eclipse Kepler, with Glassfish4 and using primefaces 4.0.This the StackTrace
2013-12-07T00:38:34.028+0100|Avertissement: #{groupeBean.createGroupe}: java.lang.NullPointerException
javax.faces.FacesException: #{groupeBean.createGroupe}: java.lang.NullPointerException
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:118)
at javax.faces.component.UICommand.broadcast(UICommand.java:315)
at javax.faces.component.UIData.broadcast(UIData.java:1108)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:790)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1282)
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:646)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:357)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:260)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:188)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:191)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:168)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:189)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:288)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:206)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:136)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:114)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:838)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:113)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:115)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:55)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:135)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:564)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:544)
at java.lang.Thread.run(Thread.java:724)
Caused by: javax.faces.el.EvaluationException: java.lang.NullPointerException
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:101)
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
... 35 more
Caused by: java.lang.NullPointerException
at com.portail.dao.DaoGroupe.ajouter(DaoGroupe.java:21)
at com.portail.managedBeans.GroupeBean.createGroupe(GroupeBean.java:24)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.sun.el.parser.AstValue.invoke(AstValue.java:275)
at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:304)
at org.jboss.weld.util.el.ForwardingMethodExpression.invoke(ForwardingMethodExpression.java:40)
at org.jboss.weld.el.WeldMethodExpression.invoke(WeldMethodExpression.java:50)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:87)
... 36 more
This is the code of the managedBean
#ManagedBean
#ViewScoped
public class GroupeBean {
private Groupe newGroupe=new Groupe();
public Groupe getNewGroupe() {
return newGroupe;
}
public void setNewGroupe(Groupe newGroupe) {
this.newGroupe = newGroupe;
}
private DaoGroupe gdao= new DaoGroupe();
public void createGroupe()
{
gdao.ajouter(newGroupe);
}}
This is the code of the Dao Class
public class DaoGroupe {
private static final String JPA_UNIT_NAME="Portail";
private EntityManager entityManager;
protected EntityManager getEntityManager() {
if (entityManager == null) {
entityManager = Persistence.createEntityManagerFactory(
JPA_UNIT_NAME).createEntityManager();
}
return entityManager;
}
public void ajouter(Groupe g)
{
EntityTransaction tx = entityManager.getTransaction();
tx.begin();
entityManager.persist(g);
tx.commit();}}
And this is the insert tab in my jsf page
<p:tab title="Groupe">
<h:form>
<h:panelGrid columns="2">
<h:outputText value="Nom : *" />
<p:inputText value="#{groupeBean.newGroupe.nom}" required="true"
label="nomgrp" validatorMessage="Nom de Groupe Obligatoire" />
<h:outputText value="Numéro : *" />
<p:inputText value="#{groupeBean.newGroupe.idGroupe}" required="true"
label="numgrp" validatorMessage="Numéro de Groupe Obligatoire" />
</h:panelGrid>
<p:commandButton value="Ajouter"
style="width:205px;margin-left:10%"
action="#{groupeBean.createGroupe}" />
</h:form>
</p:tab>

Answer 1

You get a NullPointerException in your DaoGroupe-Class within the method ajouter.
I guess the entityManager.getTransaction() is the reason, because the entityManager is not filled anywhere. Replacing it with using your getEntityManager()-method might be a first point to start debugging from.
EntityTransaction tx = getEntityManager().getTransaction();
Hope it helps...