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Following code is any example of UUID default until java class to generate a UUID as primary key in JPA entity .The idea is so simple , just set the value of UUID to the primary key before the persistence .

Here is the entity :
Code:

package com
.codemiles.jpa;
import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;


@
Entity
@Table(name="TOPIC")
public class 
Topic implements java.io.Serializable{
    
/**
     * 
     */
    
private static final long serialVersionUID 1L;
    @
Id
    
private String Id;
    private 
String title;
    private 
Date creationDate;
    private 
Date modifedDate;
    private 
String content;
    

    public 
String getId() {
        return 
Id;
    }
    public 
void setId(String id) {
        
Id id;
    }
    
    @
Column(name="TITLE")
    public 
String getTitle() {
        return 
title;
    }
    public 
void setTitle(String title) {
        
this.title title;
    }
    
    @
Column(name="CREATION_DATE")
    public 
Date getCreationDate() {
        return 
creationDate;
    }
    public 
void setCreationDate(Date creationDate) {
        
this.creationDate creationDate;
    }
    
    @
Column(name="MODIFED_DATE")
    public 
Date getModifedDate() {
        return 
modifedDate;
    }
    public 
void setModifedDate(Date modifedDate) {
        
this.modifedDate modifedDate;
    }
    
    @
Column(name="CONTENT")
    public 
String getContent() {
        return 
content;
    }
    public 
void setContent(String content) {
        
this.content content;
    }
}
 


Creating a new instance and using UUID :
Code:

package com
.codemiles.jpa;

import java.util.Date;
import java.util.UUID;
import javax.persistence.EntityManager;

public abstract class 
Loader {
    protected abstract 
EntityManager getEntityManager();
    
/**
     * @param args
     */
    
public static void main(String[] args) {
    
Topic topic = new Topic();
    
topic.setId(UUID.randomUUID().toString());
    
topic.setContent("Topic At Codemiles");
    
topic.setCreationDate(new Date(System.currentTimeMillis()));
    
topic.setModifedDate(new Date(System.currentTimeMillis()));
    
topic.setTitle("UUID topic ");
     
/*
        persistence code .
         getEntityManager().persist(topic);
      
      */
    
}

}
 




_________________
M. S. Rakha, Ph.D.
Queen's University
Canada


Author:
Mastermind
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