createEntityManagerFactoryProvider throws NullPointerException
Hi I'm new to JPA I made a very simple example like following:
Emp.java:
@Entity
@Table(name="EMP", schema="hr")
publicclass Emp{
@Id
privateint id;
@OneToOne(mappedBy="employINparkSpace")
private ParkSpace parkSpace;
@Column(name="NAME")
private String name;
@Basic(fetch=FetchType.LAZY)
@Column(name="SALARY")
privatelong salary;
@Column(name="DATEOFBIRTH")
private Date dateofBirth;
@ManyToOne
@JoinColumn(name="DEPTID")
private Dept department ;
}
Another class is:
@Entity
@Table(name="DEPT",schema="hr")
publicclass Dept{
public Dept(){}
public Dept(int id){ this.id = id;}
@Id
privateint id;
@Column(name="NAME")
private String name;
@OneToMany(targetEntity=Emp.class,mappedBy="department")
private Collection<Emp> emps;
}
in my EmpService I wrote:EntityManagerFactory emf =null;
EntityManager em =null;
EmpService eService =null;
try{
emf = Persistence.createEntityManagerFactory("EmpService");
em = emf.createEntityManager();
eService =new EmpService(em);
Collection<Emp> emps = eService.findAllEmps();
if (emps !=null){
for (Emp e : emps){
System.out.println("Found employee: "+e.getName()+" ,park Location:"+e.getParkSpace().getLocation());
}
}
}catch (Exception e){
e.printStackTrace();
thrownew Exception(e.getMessage());
}finally{
em.close();
emf.close();
}
This works fine but when I write same thing for Dept object as following:
EntityManagerFactory emf =null;
EntityManager em =null;
DeptService dService =null;
try{
emf = Persistence.createEntityManagerFactory("DeptService");
em = emf.createEntityManager();
dService =new DeptService(em);
Collection<Dept> deps = dService.findAllDepartments();
if ( deps!=null ){
for (Dept d: deps){
System.out.println("Department ID: "+d.getId()+" , department Name: "+d.getName());
}
}
}catch (Exception e){
e.printStackTrace();
thrownew Exception(e.getMessage());
}finally{
em.close();
emf.close();
}
I get following exceptions:
java.lang.NullPointerException
at oracle.toplink.essentials.ejb.cmp3.EntityManagerFactoryProvider.createEntityManagerFactory(EntityManagerFactoryProvider.java:120)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:83)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:60)
Can any one help me what is my problem ?
