[jboss-user] [EJB 3.0] - Re: generating a Primary Key using a Sequence in JPA

[ashusri000]

Hi ,
What I am trying to do is , simply trying to persist a new Object every time the main method gets called and could not see anypoint where there are multiple / double call to sequence. The sequence that I am using is not already defined in the database , I have defined it in the code itself.
Here is the code :


import java.io.Serializable;

import java.util.HashMap;

import javax.persistence.Entity;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Id;
import javax.persistence.Persistence;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.SequenceGenerator;

import javax.persistence.Table;
import javax.persistence.Column;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.DiscriminatorType;

@Entity
@Table(name="TAB1")
@DiscriminatorColumn(name="ID", discriminatorType = DiscriminatorType.INTEGER)
public class Tab1 implements Serializable {
@Id
@GeneratedValue(strategy=GenerationType.TABLE, generator = "tabGen")
@SequenceGenerator(name="tabGen" , allocationSize=1)
@Column(name="ID")
private long id;

private String val;

private static final long serialVersionUID = 1L;

public Tab1() {
super();
this.val= "hello";
}

public long getId() {
return this.id;
}

public void setId(long id) {
this.id = id;
}

public String getVal() {
return this.val;
}

public void setVal(String val) {
this.val = val;
}
public static void main(String[] args) {
EntityManagerFactory emf =
Persistence.createEntityManagerFactory("testApp", new HashMap());
EntityManager em = emf.createEntityManager();

try{
em.getTransaction().begin();
em.persist(new Tab1());
System.out.println("Done");
em.getTransaction().commit();
System.out.println("Entered the Values");
}catch (Exception e) {
e.printStackTrace();
}finally{
em.close();
}
}
}

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