Question

I am learning Hibernate from the tutorials on JBoss website. I have a confusion in a code example located here.

There is a Cat class code at 4.1. A simple POJO example.

This Cat class has a reference to his mother as private Cat mother;

Q1. If the class has an identifier property as id, then wouldn’t it be better to store the cat’s mother’s id instead of cat’s mother object.

means instead of

private Cat mother;

wouldn’t it be better to have

private long motherId; 

`

Answer 1

That’s what hibernate implicitly does for you.

The good thing about ORM is that it completely hides implementation caveats due to the fact that you are working on a RDBMS instead that with plain objects. You can use mother as Cat without bothering about the fact that its relation it’s expressed by an id internally.