Question

In the below code every time I need to get Dept object by passing deptId in createUser() when i am persist Emp, I don’t want to go to a database.I want like JDBC to pass only id not object. Every time getting from database effects performance. How do I do that?

public class Emp {
  Integer eid;
  String ename;
  long sal;
  Dept dept;    

  public void createUser(Integer eid,String ename,long sal,Integer deptId) {
    Dept dept = em.find(Dept.class,deptId);
    Emp emp = new Emp();
    emp.setEid(101);
    emp.setEname("Smith");
    emp.setSal(100000);
    emp.setDept(dept);    // here Dept object required 
    em.persist(emp);
  }

}

public class Dept {
  Integer deptid;
  String deptname;
}

Answer 1

I think em.getReference() suits those needs