ProductUpdateTest.java

package com.test.jpa;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;

public class ProductUpdateTest {
	
	public static void main(String[] args) {
		
		EntityManagerFactory factory=Persistence.createEntityManagerFactory("JPATest");
		
		EntityManager entityManager=factory.createEntityManager();
		
		entityManager.getTransaction().begin();
		
		Product product=entityManager.find(Product.class, 2);
		
		product.setName("Computer");

		entityManager.merge(product);
		
		entityManager.getTransaction().commit();
		
		entityManager.close();
		
		factory.close();
		
		
    }

}