This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
"Persist" can be understood to mean many different things. APIs like JPA work with annotations to indicate how objects should be persisted to a DB.
Persisting a serialized binary version of an object is a fraught business that should be avoided. Slightly better (if using something like JPA is not an option) would be to use the java.beans.XMLEncoder/XMLDecoder classes (assuming that the objects follow JavaBean semantics).