保存对象/ Hibernate上的java.lang.NullPointerException

Question

I'm trying to save an object in my MySQL database with Hibernate and Spring, in HQL. However, when saving, here is the error message:

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException

public void addCountry(Country country) throws Exception {

    Session session = sessionFactory.openSession();
    Transaction transaction = null;

    try {
        transaction = session.beginTransaction();

        //Add new Country object
        Country c = new Country();
        c.setId(""); //id value is auto into mySQL
        c.setCity1(country.getCity1());
        c.setCity2(country.getCity2());
        session.save(c);

        transaction.commit();

    } catch (Exception e) {
        if (transaction != null) {
            transaction.rollback();
        }
        throw e;
    } finally {
        session.close();
    }
}

Answer 1

As juanlumn said remove setId("") as Hibernate will create this for you. Need to debug to see which object is causing NullPointerException like need to know if you are getting Hibernate session which will let you know that you have configured Hibernate properly. Again you are passing country as method parameter but saving c by populating in dao itself not sure why.