a question that is often faced by RDF developers: how to change those RDF graphs?

ususally, you would use jena or sesame's api to directly add triples, delete them, list classes using (x rdf:type rdfs:class) and so on...

Then, some developers make libraries that allow you to generate code that wraps the RDF in an object model.

This means, instead of adding triple
X.addProperty(FOAF.name, "Leo");
you say:
X.setFoafName("Leo");
where the setFoafName method was generated by such a code generator.

Now some code generators for you:

• rdf2java by Sven Schwarz, DFKI. Jena based, works on RDFS and OWL. used in some research projects.
• SWeDE by BBN. they mention Kazuki code generation.
• rdfreactor by some Karlsruhe guys.

from my perspective, all of them do the same. pick what you like.