JPA - EntityManager.lock Examples

    private static void updateArticle() {
        System.out.println("-- updating article --");
        EntityManager em = entityManagerFactory.createEntityManager();
        Article article = em.find(Article.class, 1L);
        em.getTransaction().begin();
        em.lock(article, LockModeType.OPTIMISTIC_FORCE_INCREMENT);
        if (article.getContent().length() < 5) {
            article.setContent("updated content");
        }
        em.getTransaction().commit();
        em.close();
        System.out.println("Article updated : " + article);
    }

    private static void employeeUpdate() {
        EntityManager em = entityManagerFactory.createEntityManager();
        Employee employee = em.find(Employee.class, 1L);
        em.getTransaction().begin();
        em.lock(employee.getDepartment(), LockModeType.OPTIMISTIC_FORCE_INCREMENT);
        employee.setSalary(3000);
        try {
            TimeUnit.SECONDS.sleep(1);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("-- updating employee --");
        em.getTransaction().commit();
        em.close();
        System.out.println("Employee updated 1: " + employee);
    }