Why EJB is null?

java ejb ejb-3.1

11,591

You need to either implement a @Local annotated interface that expresses the local view of that EJB bean, or you need to add the @LocalBean annotation to the HotelService class itself to explicitly state that it is a local no-interface view of that EJB.

@Stateless
@EJB(beanInterface = HotelService.class, name = "HotelService")
@LocalBean
public class HotelService {
    // ...
}

If you want the service to be available outside of the container for RMI or EJB client execution, you'll need to create a @Local and @Remote view of that service and implement both.

11,591

Author by

Mr Kohn Doew

Updated on June 04, 2022

Comments

Mr Kohn Doew almost 2 years
I'm working on rest service and learning EJB at the same time. I just run my application with simple chain controller -> service -> DAO and my EJB hotelService is not injected -- it is null.
```
@Path("/hotels")
public class HotelsController {

@EJB
private HotelService hotelService;


@GET
@Produces(MediaType.APPLICATION_JSON)
public Response getHotelsList(@QueryParam("startDate") String startDate,
                              @QueryParam("endDate") String endDate) {
    List<HotelsEntity> list = hotelService.getAll();
    return ResponseFactory.response(Response.Status.OK, list);
}
}
```
Service
```
@Stateless
@EJB(beanInterface = HotelService.class, name = "HotelService")
public class HotelService {

@EJB
private HotelDAO hotelDAO;

public List<HotelsEntity> getAll() {
    return hotelDAO.getAll();
}

public Hotel getHotelById(final String id) {
    return hotelDAO.getHotelById(id);
}
}
```
DAO
```
@Stateless
public class HotelDAO {

@PersistenceContext(unitName = Constants.PERSISTENCE_UNIT)
private EntityManager em;

public List<HotelsEntity> getAll() {
    // TODO complete me
    CriteriaBuilder builder = em.getCriteriaBuilder();
    CriteriaQuery<HotelsEntity> criteria = builder.createQuery(HotelsEntity.class);
    Root<HotelsEntity> root = criteria.from(HotelsEntity.class);
    criteria.select(root);
    TypedQuery<HotelsEntity> resultQuery = em.createQuery(criteria);
    return resultQuery.getResultList();
}
```
I thought that issue may be in some eror during instatiation of HotelDAO but even without it mt HotelService is null.

Do you a have any opinion where is an issue can be?

I use glassfish 4.0 My pom is:
```
  <modelVersion>4.0.0</modelVersion>
<groupId>HospitalityRestServer</groupId>
<artifactId>HospitalityRestServer</artifactId>
<packaging>war</packaging>

<version>1.0-SNAPSHOT</version>
<name>HospitalityRestServer Maven Webapp</name>
<url>http://maven.apache.org</url>

<dependencies>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>4.3.5.Final</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>3.8.1</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>javax.ws.rs</groupId>
        <artifactId>javax.ws.rs-api</artifactId>
        <version>2.0</version>
    </dependency>
    <dependency>
        <groupId>org.glassfish.jersey.core</groupId>
        <artifactId>jersey-server</artifactId>
        <version>2.7</version>
    </dependency>
    <dependency>
        <groupId>org.glassfish.jersey.media</groupId>
        <artifactId>jersey-media-json-jackson</artifactId>
        <version>2.4</version>
    </dependency>
    <dependency>
        <groupId>org.apache.tomcat</groupId>
        <artifactId>annotations-api</artifactId>
        <version>6.0.29</version>
    </dependency>
    <dependency>
        <groupId>org.glassfish</groupId>
        <artifactId>javax.ejb</artifactId>
        <version>3.1</version>
    </dependency>
</dependencies>
```
Log:
```
[2014-04-28T17:58:05.828+0400] [glassfish 4.0] [WARNING] [] [javax.enterprise.web] 
tid: _ThreadID=22 _ThreadName=http-listener-1(4)] [timeMillis: 1398693485828] [levelValue: 900] [[
```
StandardWrapperValve[javax.ws.rs.core.Application]: Servlet.service() for servlet javax.ws.rs.core.Application threw exception java.lang.NullPointerException at com.example.controller.HotelsController.getHotelsList(HotelsController.java:29) 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 org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory$1.invoke(ResourceMethodInvocationHandlerFactory.java:81) at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:125) at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$ResponseOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:152) at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:91) at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:346) at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:341) at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:101) at org.glassfish.jersey.server.ServerRuntime$1.run(ServerRuntime.java:224) at org.glassfish.jersey.internal.Errors$1.call(Errors.java:271) at org.glassfish.jersey.internal.Errors$1.call(Errors.java:267) at org.glassfish.jersey.internal.Errors.process(Errors.java:315) at org.glassfish.jersey.internal.Errors.process(Errors.java:297) at org.glassfish.jersey.internal.Errors.process(Errors.java:267) at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317) at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:198) at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:946) at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:323) at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:372) at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:335) at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:218) 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:745) ]]
Mr Kohn Doew about 10 years

Thanks for your answer, but it doesn't help -- I marked it as LocalBean but issue is the same
jgitter about 10 years

After doing a little reading on the java ee 7 docs, I realized that the @LocalBean is not actually required. Are you getting any other errors on startup? Have you checked the server logs?
Mr Kohn Doew about 10 years

Yes, on startup I had an issue described here java.net/jira/browse/GLASSFISH-20579 and I resolved it by setting asadmin set configs.config.server-config.cdi-service.enable-implicit-cdi‌=false That is all, log doesn't have anything else
jgitter about 10 years

That may come back to bite you if you ever choose to use CDI in your application. But regardless, it sounds like you need to raise the log levels for your application. Also... can I see the NPE being thrown when you attempt to call your web service?
jgitter about 10 years

Wait a minute... I just noticed you're also injecting the DAO into your Service class. Can I see the annotations you have on that object?
Mr Kohn Doew about 10 years

Update with log. An a few minutes update and DAO but I also had tried without DAO -- issue is the same
Mr Kohn Doew about 10 years

Update DAO. Too short
jgitter about 10 years

The only other thing I can think of is that EJBs have to be injected into managed objects and apparently your service doesn't qualify. Try making your service a @Stateless bean, rebuild and try again. If that is the case, and you don't wish to add the overhead of another bean, try using CDI instead. :-)
Mr Kohn Doew about 10 years

Well, my service is already a stateless bean :)
jgitter about 10 years

I'm not talking about the HotelService object. I'm talking about the HotelController object which exposes a JAX-RS web service.
jgitter about 10 years

Let me know if this works and I'll update my answer.
Mr Kohn Doew about 10 years

I resolved it - I have added a bean.xml. I'm appreciate all your help jgitter. Thank you!
Mr Kohn Doew about 10 years

I mark it as answer because at least it ha an answer in comments
jgitter about 10 years

Congrats and cheers to you!