Is it possible to use annotations in plain J2SE-applications? I've gotten the following error messages when I've played around with it:

Using @Entity and @Id => compilation error:
cannot find symbol Id

Using @Entity without @Id => runtime error:
Initial SessionFactory creation failed. java.lang.NoClassDefFoundError: javax/persistence/Entity

Since I can't imagine anybody would want to use XML files instead of annotations, I guess there is a way to get around it?

You should add ejb3-persistence.jar in your classpath... (It is given in the lib directory of hibernate annotations)

schuer