Hi,

In the class below, the two lists, one allocated while another not, all works, any difference? what is the correct way to handle a one to many situation like this? Thanks,

Angelo

public class User {

private Long id;

private List<Address> addresses;
private List<Contact> contacts = new ArrayList<Contacts>();

}

As far as i know this only makes a difference outside the persistence context, as soon as you access the collection inside a session you will always get a least an empty list, never null.

So it's up to you, but i would suggest going one way or the other for code consistency.

Is a detached object consider as outside of persistence context?

A detached object was previously attached so it was initialized by hibernate. The collections also should never be null. As pkleindl says, the only difference is, when you create objects of User using the constructor.