3.2. Making objects persistent

Once you've created a new entity instance (using the common new operator) it is in the new state. You can make it persistent by associating it to an entity manager:

DomesticCat fritz = new DomesticCat();
fritz.setColor(Color.GINGER);
fritz.setSex('M');
fritz.setName("Fritz");
em.persist(fritz);

If the DomesticCat entity type has a generated identifier, the value is associated to the instance when persist() is called. If the identifier is not automatically generated, the application-assigned (usually natural) key value has to be set on the instance before persist() is called.