Struts 2 Hibernate null pointer exception while submitting the form

Question

I am trying to create a registration page by integrating Struts 2 & Hibernate. But when I am running the below code , I am getting a null pointer exception when I click

Answer 1

You misunderstand the DAO/DTO pattern. DAO/DTOs should not be static. And the sessionFactory better build normally only once per application, because it's time consuming procedure.

Better for you to implement a session per thread pattern. Write the class HibernateUtil to build the sessionFactory and get the session.

Then your DAO will look like

public class UserDao {

    public Session getSession() {
      return HibernateUtil.getSession();
    }

    public void closeSession() {
      HibernateUtil.closeSession();
    }

    public void addUser(User u) {    
        Session session = getSession();
        Transaction t = session.beginTransaction();
        int i = (Integer)session.save(u);
        t.commit();
        closeSession();
    }
}

in the action you write

private UserDao userDao = new UserDao();

public String execute() throws Exception {
    User u = new User();
    u.setAddress(address);
    u.setEmail(email);
    u.setName(name);
    u.setPhno(phno);
    u.setPwd(pwd);
    userDao.addUser(u);
    return "success";
}