EntityManager em = Persistence.createEntityManagerFactory("myPersistenceUnit").createEntityManager(); if(em.isOpen()) { System.out.println("EntityManager is open"); } else { System.out.println("EntityManager is closed"); }
EntityManagerFactory emf = Persistence.createEntityManagerFactory("myPersistenceUnit"); EntityManager em = emf.createEntityManager(); try { // perform database operations using EntityManager } finally { if(em.isOpen()) { em.close(); } }In this example, we create an EntityManagerFactory object using persistence unit "myPersistenceUnit". Then, we create an EntityManager object using createEntityManager() method of the EntityManagerFactory. We perform some database operations using EntityManager. Finally, we use isOpen() method to check if EntityManager is open and close it using close() method. The package library for javax.persistence.EntityManager isOpen method is javax.persistence.