I am curious about the implementation of hibernate about
the lazy initialization of collections.

within a hibernate session,
in which way does hibernate knows some code is using the collection
and then initialize the specified collection?

how?somebody who read this part of
source code please help me explain this,thank you.

I guess that the Hibernate create proxies insteard the actual collection elements. An proxy object is called while access to the the collection element. I hope it is clear.

And what will happens, if you call collection.size() - I don't really know.

but it doesnot act like a proxy thing....

when I called



the association is not initilized;

when I called



this time the association is initilized.


does it?

As I see, you don't use real object methods in this case.

opposite in this case:

you implict call .toString.

Hibernate has it's own custom implementations of each of the collection interfaces. It replaces your collections with an instance of one of these when persist() is called. See here: http://www.hibernate.org/hib_docs/v3/re ... tions.html for details.

This allows hibernate to set up the collections on an object without initialising them. (Which explains why myObj.getAssociations() does not need to initialise the collection). When size() or one of the get methods is called hibernate can issue a query that gets a list of keys of objects in the collection. It can use this query to work out the size of the collection (the result count) and provide proxies for all of the objects in the collection. This is why your second example initialises the collection and one of the proxies.