Java Data Object (JDO) can be used to build an application that creates, reads, updates, and deletes persistent instances of Java classes. These objects can be persisted on to relation database, object oriented database or on to XML files. This depends on the implementation of JDO you are using.
One needs to get the basics before starting working with JDO. Once you have the basics, you can map java objects to the data source transparently.
JDO allows you to map your