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.
An XML file can be converted into a class hierarchy using JAXB but am not sure if a schema definition is mandatory for the operation. In case there is a dependency on XSD for this operation you can approach the same using JAXP parsers and POJOs. You will have to have the code which uses SAX/DOM parser APIs, iterate through the elements and set the values for the properties in the hierarchy.
I you were to give more details on what you are trying to accomplish, I might be able to suggest further options available.