Initializing a new entity bean with relations

[treespace]

I have a new entity Author and want to add a Book. The book list is empty which generates an exception in author.getBooks().add( new Book() ). Two questions.

First, can any old List implementation be used to initialize the list? My impression was that was a special implementation of List with a plain old List interface.

Second, what is the best-practice in terms of initializing? Should the Author's books field new its own ArrayList? Will the loader use that or create another?

public class Author
{
 private List<Book> books = new ArrayList<Book>();
 ...

[treespace]

First part of answer is you can use any old list since otherwise it's not a POJO. Second, you initialize your own collections or pre-check for null. Pre-initializing is the lesser of two evils.

[epbernard]

I usually do

private List<Book> books = new ArrayList<Book>();