Question

I created simple DB with LibreOffice Base and exported it with SCRIPT command. It has only one table Tag with “id” and name. I created corresponding class named Tag, with annotation @Entity, and for id @Id.

I load data with following code:

public static void main(String[] args){     

    Configuration configuration=new Configuration();
    configuration.configure();
    serviceRegistry=new ServiceRegistryBuilder().applySettings(
    configuration.getProperties()).buildServiceRegistry();
    sessionFactory=configuration.buildSessionFactory(serviceRegistry);
    session=sessionFactory.openSession();
    session.beginTransaction();

    tag=(Tag) session.get(Tag.class, 1);
    session.close();
    System.out.println(tag.getName());
}

Running this i get follwing lines:

Hibernate: select tag0_.id as id0_0_, tag0_.name as name0_0_ from Tag tag0_ where tag0_.id=?

and NullPointerException.

in xml file i have specified the file to be used “jdbc:hsqldb:file:testdb”, also added Tag as a mapping class.. What i am doing wrong??

Answer 1

If you use Hibernate+HSQLDB for testing you could set property “hibernate.hbm2ddl.auto” to
“create” – in that case hibernate will create required schema by itself

hibernate.hbm2ddl.auto Automatically validates or exports schema DDL
to the database when the SessionFactory is created. With create-drop,
the database schema will be dropped when the SessionFactory is closed
explicitly.