NullPointerException in JSF Converter - jsf

Question

I have a table Users and Specializations in database
Users:
CREATE TABLE IF NOT EXISTS `ePrzychodnia`.`users` (
`id` INT NOT NULL AUTO_INCREMENT ,
`firstName` VARCHAR(45) NOT NULL ,
`lastName` VARCHAR(45) NOT NULL ,
`specialization_id` INT NULL ,
PRIMARY KEY (`id`) ,
UNIQUE INDEX `personalId_UNIQUE` (`personalId` ASC) ,
INDEX `fk_users_specializations1_idx` (`specialization_id` ASC) ,
CONSTRAINT `fk_users_specializations1`
FOREIGN KEY (`specialization_id` )
REFERENCES `ePrzychodnia`.`specializations` (`id` )
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
Specializations:
CREATE TABLE IF NOT EXISTS `ePrzychodnia`.`specializations` (
`id` INT NOT NULL ,
`name` VARCHAR(45) NOT NULL ,
PRIMARY KEY (`id`) ,
UNIQUE INDEX `name_UNIQUE` (`name` ASC) )
ENGINE = InnoDB;
Entity class:
Users:
public class User implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Basic(optional = false)
#Column(name = "id")
private Integer id;
#Basic(optional = false)
#NotNull
#Size(min = 1, max = 45)
#Column(name = "firstName")
private String firstName;
#Basic(optional = false)
#NotNull
#Size(min = 1, max = 45)
#Column(name = "lastName")
private String lastName;
#Basic(optional = false)
#JoinColumn(name = "specialization_id", referencedColumnName = "id")
#ManyToOne
private Specialization specializationId;
Specialization:
public class Specialization implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#Basic(optional = false)
#NotNull
#Column(name = "id")
private Integer id;
#Basic(optional = false)
#NotNull
#Size(min = 1, max = 45)
#Column(name = "name")
private String name;
#OneToMany(mappedBy = "specializationId")
private Collection<User> userCollection;
and I try create converter to one select menu in JSF:
SelectOneMenu:
<h:outputLabel for="specialization" value="#{msg.specialization}"/>
<p:selectOneMenu id="specialization" value="#{userMB.user.specializationId}" effect="fade" style="width:200px" converter="specializationConverter">
<f:selectItems value="#{specializationMB.allSpecialization}" var="specialization" itemValue="#{specialization}" itemLabel="#{specialization.name}"/>
</p:selectOneMenu>
<p:message for="specialization"/>
and Converter:
public class SpecializationConverter implements Converter{
private SpecializationDao specializationDao = new SpecializationDao();
#Override
public Object getAsObject(FacesContext context, UIComponent component, String value) {
//throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
Integer id = Integer.parseInt(value);
return specializationDao.find(id);
}
#Override
public String getAsString(FacesContext context, UIComponent component, Object value) {
//throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
return ((Specialization) value).getId().toString();
}
}
But convertert dont work;/ I have a error:
WARNING: StandardWrapperValve[Faces Servlet]: PWC1406: Servlet.service() for servlet Faces Servlet threw exception
java.lang.NullPointerException
at pl.Project.dao.SpecializationDao.find(SpecializationDao.java:36)
at pl.Project.converter.SpecializationConverter.getAsObject(SpecializationConverter.java:29)
SpecializationDao:
#Stateless
public class SpecializationDao implements SpecializationDaoLocal {
#PersistenceContext
private EntityManager em;
private Specialization specialization;
public SpecializationDao() {
}
public SpecializationDao(Specialization specialization) {
this.specialization = specialization;
}
#Override
public Specialization find(int specializationId) {
return em.find(Specialization.class, specializationId);
}
#Override
public List<Specialization> findAllSpecialization() {
Query q = em.createNamedQuery("Specialization.findAll");
List<Specialization> specializations = q.getResultList();
return specializations;
}
}