hello,

I use hibernate with an in-process HSQLDB in my application to save
projects (an instance of Project with about 7 other classes involved) to
disk. Obviously the structure of these classes may change.

So when loading a project from hibernate persistence, I need to check the
version of each class (instance variable 'version' that is persisted),
and load the class matches the version:

My idea is to create a subclass of each class that has changed
(i.e. ProjectV2 extends Project, ProjectV3 extends ProjectV2 and so on),
and when loading a project, read the version-number, load the appropriate
class (i.e. ProjectV2) using hibernate, and then convert it to the current
version using a constructor (i.e. ProjectV3).

My question is:
Is there a better way to do this, or a feature in hibernate that makes this
easier?

Thanks in advance!