Nullpointerexception Java JPA CDI Tomcat

Question

Good afternoon guys. I am developing a Java test application with JPA, CDI and Tomcat. I created a basic test class and am getting the following error.

Erro: Exception in thread "main" java.lang.NullPointerException
    at br.com.hcancerbarretos.espec.dao.EspecialidadesDAO.getEspecialidades(EspecialidadesDAO.java:16)
    at br.com.hcancerbarretos.espec.testes.Teste.main(Teste.java:13)

To EspecialidadeDAO is null, is not being injected correctly with the @Inject. The strange thing is that if I create a JSF page and display the values in a datatable, all that has @Inject is injected normally. I also created a Webservice class called Specialties, where the Specialty Dependency injection does not work.

Can anyone tell me how to fix it? Why? Any output? Below are the files and classes.

Model class:

import java.io.Serializable;
import javax.persistence.*;
import java.util.Date;

@Entity
@NamedQuery(name="Especialidade.findAll", query="SELECT e FROM Especialidade e")
public class Especialidade implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @Column(name="ESPECEALIDADE_ID")
    private long especialidadeId;

    private String descricao;

    @Temporal(TemporalType.DATE)
    @Column(name="DT_ALT")
    private Date dtAlt;

    @Temporal(TemporalType.DATE)
    @Column(name="DT_INCL")
    private Date dtIncl;

    private String sigla;

    @Column(name="USU_ALT")
    private String usuAlt;

    @Column(name="USU_INCL")
    private String usuIncl;

    public Especialidade() {
    }

    //getters and setters ...
}

Class code Speciality.

import java.util.List;
import javax.inject.Inject;
import javax.persistence.EntityManager;
import br.com.hcancerbarretos.espec.model.Especialidade;

public class EspecialidadesDAO {

    @Inject
    private EntityManager em;

    public List<Especialidade> getEspecialidades() {
        return em.createNamedQuery("Especialidade.findAll", Especialidade.class).getResultList();
    }

    public String getEspecialidadePorCodigo(long codigo) {
        return em.createQuery("select e.descricao From Especialidade e Where e.especialidadeId = :codigo", String.class)
                .setParameter("codigo", codigo).getSingleResult();
    }
}

Class EntityManagerProducer:

import javax.enterprise.context.ApplicationScoped;
import javax.enterprise.context.RequestScoped;
import javax.enterprise.inject.Disposes;
import javax.enterprise.inject.Produces;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;

@ApplicationScoped
public class EntityManagerProducer {

    private EntityManagerFactory factory;

    public EntityManagerProducer() {
        this.factory = Persistence.createEntityManagerFactory("Especialidade");
    }

    @Produces
    @RequestScoped
    public EntityManager createEntityManager() {
        return factory.createEntityManager();
    }

    public void closeEntityManager(@Disposes EntityManager manager) {
        manager.close();
    }

}

Test class:

import java.util.List;
import br.com.hcancerbarretos.espec.dao.EspecialidadesDAO;
import br.com.hcancerbarretos.espec.model.Especialidade;

public class Teste {

    public static void main(String[] args) {        
        EspecialidadesDAO dao = new EspecialidadesDAO();
        List<Especialidade> especialidades = dao.getEspecialidades();        
    }
}

Class Especialidadews.

import javax.inject.Inject;
import br.com.hcancerbarretos.espec.dao.EspecialidadesDAO;

public class EspecialidadeWS {

    @Inject
    private EspecialidadesDAO dao;

    public String getEspecialidade(long codigo){
        System.out.println("DAO " + dao);
        return dao.getEspecialidadePorCodigo(codigo);
    }   
}

Filing cabinet web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    version="2.5">

    <display-name>Especialidade</display-name>

    <welcome-file-list>
        <welcome-file>index.jsf</welcome-file>
        <welcome-file>index.xhtml</welcome-file>
    </welcome-file-list>

    <servlet>
        <servlet-name>Faces Servlet</servlet-name>
        <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>*.jsf</url-pattern>
    </servlet-mapping>

    <listener>
        <listener-class>org.jboss.weld.environment.servlet.Listener</listener-class>
    </listener>
    <resource-env-ref>
        <resource-env-ref-name>BeanManager</resource-env-ref-name>
        <resource-env-ref-type>javax.enterprise.inject.spi.BeanManager</resource-env-ref-type>
    </resource-env-ref>

</web-app>

Filing cabinet META-INF\context.xml:

<?xml version="1.0" encoding="UTF-8"?>
<Context>
    <!-- disables storage of sessions across restarts -->
    <Manager pathname="" />
    <Resource name="BeanManager" auth="Container"
        type="javax.enterprise.inject.spi.BeanManager" factory="org.jboss.weld.resources.ManagerObjectFactory" />
</Context>

The archive beans.xml is created, but empty, as recommended.

Answer 1

try this

public class EspecialidadeWS {

    @Inject
    private EspecialidadesDAO dao;

    public String getEspecialidade(long codigo){
        try{
            String codigo = dao.getEspecialidadePorCodigo(codigo);
            return codigo;
        }catch (NullPointerException e) {
            // TODO: handle exception
            return ''
        }
    }   
}

You are not treating the code in case the specialty does not exist. Another thing I could observe is that the attribute "description" and others is not mapped in its entity. Map...

@Column(name="ESPECEALIDADE_ID")
private String descricao;

Answer 2

If you are trying to use the main method will not work!

Because: You’re using a resource called CDI, which is basically a module running in your application container that whenever an instance annotated with @EJB or @Inject is used it intercepts the thread and passes an instance it creates itself, or reuses. Basically speaking, running on Tomcat is he who makes a "new Object()" in the entityManager inside Specialtyfor you.

Running on main you will have to create the instance of Entitymanager using Entitymanagerfactory and pass it into your Expertise, just because there’s no little robot doing the job for you.

Answer 3

Write down your class EspecialidadeWS with @javax.enterprise.context.RequestScoped to function as web service.

EDIT:

In my projects I use the Resteasy together with the CDI to run the injection you want. Come on: you also need to create, in your project, a class that extends the javax.ws.rs.core.Application:

package abc;

import abc.EspecialidadeWS;

import javax.ws.rs.core.Application;
import java.util.HashSet;
import java.util.Set;

public class AppRs extends Application {

    private Set<Class<?>> classes;

    public AppRs() {
        classes = new HashSet<>();
        classes.add(EspecialidadeWS.class);
    }

    @Override
    public Set<Class<?>> getClasses() {
        return classes;
    }
}

In the web.xml:

<!--  RESTEasy  -->
<listener>
    <listener-class>
        org.jboss.resteasy.plugins.server.servlet.ResteasyBootstrap
    </listener-class>
</listener>
<servlet>
    <servlet-name>RESTEasy Servlet</servlet-name>
    <servlet-class>
        org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher
    </servlet-class>
    <init-param>
        <param-name>javax.ws.rs.Application</param-name>
        <param-value>br.com.t2tecnologia.AppRs</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>RESTEasy Servlet</servlet-name>
    <url-pattern>/rest/*</url-pattern>
</servlet-mapping>
<context-param>
    <param-name>resteasy.servlet.mapping.prefix</param-name>
    <param-value>/rest</param-value>
</context-param>
<context-param>
    <param-name>resteasy.injector.factory</param-name>
    <param-value>org.jboss.resteasy.cdi.CdiInjectorFactory</param-value>
</context-param>

In the pom.xml (Maven):

<!--  CDI (esse você já deve ter)  -->
<dependency>
    <groupId>org.jboss</groupId>
    <artifactId>jandex</artifactId>
    <version>2.0.1.Final</version>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>org.jboss.weld.servlet</groupId>
    <artifactId>weld-servlet</artifactId>
    <version>2.3.2.Final</version>
    <scope>runtime</scope>
</dependency>
<!--  RESTEasy  -->
<dependency>
    <groupId>org.jboss.resteasy</groupId>
    <artifactId>resteasy-jaxrs</artifactId>
    <version>3.0.16.Final</version>
</dependency>
<dependency>
    <groupId>org.jboss.resteasy</groupId>
    <artifactId>resteasy-servlet-initializer</artifactId>
    <version>3.0.16.Final</version>
</dependency>
<dependency>
    <groupId>org.jboss.resteasy</groupId>
    <artifactId>resteasy-cdi</artifactId>
    <version>3.0.16.Final</version>
</dependency>
<dependency>
    <groupId>org.jboss.resteasy</groupId>
    <artifactId>resteasy-jackson-provider</artifactId>
    <version>3.0.16.Final</version>
</dependency>
<dependency>
    <groupId>org.codehaus.jackson</groupId>
    <artifactId>jackson-mapper-asl</artifactId>
    <version>1.9.13</version>
</dependency>

Class EspecialidadeWS:

@Path("/especialidade")
@GET
public class EspecialidadeWS {

    @Inject private EspecialidadesDAO dao;

    @GET
    @Path("/get/{codigo}")
    public String getEspecialidade(@PathParam("codigo") long codigo){
        return dao.getEspecialidadePorCodigo(codigo);
    }   
}

Finally, write down EspecialidadeWS also with @javax.ws.rs.Path("/especialidade"). If everything works, you should be able to access your web service via http://localhost:8080/seu_projeto/Rest/especialidade/get/1, for example.