EntityManager returns NullPointerException when persisting

Question

When I persist a "Joueur" (cf my class below), I get a NullPointerException, but I don't know why

em.persist(new Joueur("pseudo", "mdp", "mail"));

This is my class "Joueur" :

@Entity
@NamedQueries({
@NamedQuery(name = "trouverParMail", query = "SELECT * FROM Joueur j WHERE j.mail = :mail")})
public class Joueur implements Serializable {
private static final long serialVersionUID = 1L;

private String pseudo;
private String mdp;
private String mail;
private Integer nbParties;
private Integer nbPartiesGagnees;

public Joueur() {
}

public Joueur(String pseudo, String mdp, String mail)
{
    this.pseudo = pseudo;
    this.mdp = mdp;
    this.mail = mail;

    this.nbParties = 0;
    this.nbPartiesGagnees = 0;
}

@Id
public String getPseudo()
{
    return pseudo;
}

public String getMdp()
{
    return mdp;
}

public String getMail()
{
    return mail;
}

public Integer getNbParties()
{
    return nbParties;
}

public Integer getNbPartieGagnees()
{
    return nbPartiesGagnees;
}

public void setPseudo(String pseudo) {
    this.pseudo = pseudo;
}

public void setMdp(String mdp) {
    this.mdp = mdp;
}

public void setMail(String mail) {
    this.mail = mail;
}

public void setNbParties(Integer nbParties)
{
    this.nbParties = nbParties;
}

public void setNbPartiesGagnees(Integer nbPartiesGagnees)
{
    this.nbPartiesGagnees = nbPartiesGagnees;
}

}

and the error stack :

java.lang.NullPointerException
at login.LoginBean.inscription(LoginBean.java:46)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.glassfish.ejb.security.application.EJBSecurityManager.runMethod(EJBSecurityManager.java:1052)
at org.glassfish.ejb.security.application.EJBSecurityManager.invoke(EJBSecurityManager.java:1124)
at com.sun.ejb.containers.BaseContainer.invokeBeanMethod(BaseContainer.java:5388)
at com.sun.ejb.EjbInvocation.invokeBeanMethod(EjbInvocation.java:619)
at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:800)
at com.sun.ejb.EjbInvocation.proceed(EjbInvocation.java:571)
at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.doAround(SystemInterceptorProxy.java:162)
at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.aroundInvoke(SystemInterceptorProxy.java:144)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.sun.ejb.containers.interceptors.AroundInvokeInterceptor.intercept(InterceptorManager.java:861)
at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:800)
at com.sun.ejb.containers.interceptors.InterceptorManager.intercept(InterceptorManager.java:370)
at com.sun.ejb.containers.BaseContainer.__intercept(BaseContainer.java:5360)
at com.sun.ejb.containers.BaseContainer.intercept(BaseContainer.java:5348)
at com.sun.ejb.containers.EJBObjectInvocationHandler.invoke(EJBObjectInvocationHandler.java:206)
at com.sun.ejb.containers.EJBObjectInvocationHandlerDelegate.invoke(EJBObjectInvocationHandlerDelegate.java:79)
at $Proxy255.inscription(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.sun.corba.ee.impl.presentation.rmi.StubInvocationHandlerImpl.privateInvoke(StubInvocationHandlerImpl.java:241)
at com.sun.corba.ee.impl.presentation.rmi.StubInvocationHandlerImpl.invoke(StubInvocationHandlerImpl.java:152)
at com.sun.corba.ee.impl.presentation.rmi.codegen.CodegenStubBase.invoke(CodegenStubBase.java:227)
at login.__LoginRemote_Remote_DynamicStub.inscription(login/__LoginRemote_Remote_DynamicStub.java)
at login._LoginRemote_Wrapper.inscription(login/_LoginRemote_Wrapper.java)
at org.apache.jsp.inscription_jsp._jspService(inscription_jsp.java from :95)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:111)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:770)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:403)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:473)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:377)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:770)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1542)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:849)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:746)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1045)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:228)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:680)

Do you know where is the error ? Tkx

Check `login.LoginBean.inscription(LoginBean.java:46)` that throw error. — Pau Kiat Wee, May 26 '12 at 13:46
The exception is thrown in `LoginBean.inscription()` method. Can you post that method? Where do you have the EntityManager (em) injected and how ? — Ahamed Mustafa M, May 26 '12 at 13:46
The code at line 46 is just : em.persist(new Joueur("pseudo", "mdp", "mail")); In my class em is private EntityManager em; — g123k, May 26 '12 at 13:47
Clearly, your EntityManager has not been properly instanciated. Can you show us the code where it is created / injected? — Jean Logeart, May 26 '12 at 13:48

score 3 · Answer 1 · answered May 27 '12 at 11:50

According description you gave, origin of NullPointerException is in this line:

em.persist(new Joueur("pseudo", "mdp", "mail"));

Only possible cause is that em is null. Likely reason for it being null is that LoginBean failed to inject EntityManager. If so, maybe LoginBean is not container managed component? Maybe you forgot @Stateless annotation?

If this didn't answered to your question, you have to share more details:

How do you obtain reference to entity manager?
Does it work in some other class?
How does code for LoginBean look like?

score -4 · Answer 2 · answered May 26 '12 at 13:57

-4

This is an Architectural problem with your Application. Check the Log-Files.

answered May 26 '12 at 13:57

Grim

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EntityManager returns NullPointerException when persisting

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