public void insert(String email, String pass, String name) {
    User user = new User();
    user.setEmail(email);
    user.setPassword(pass);
    user.setName(name);
    em.persist(user);
    System.out.println(user);
}
public void update(Long id, String name) {
    User user = em.find(User.class, id);
    user.setName(name);
    em.merge(user);
    System.out.println(user);
}
public boolean delete(Long id) {
    User user = em.find(User.class, id);
    if (user != null) {
        em.remove(user);
        return true;
    }
    return false;
}