Referencing Datatypes in Class Instances

Hi all,
 
  I'm working on "hello world" in RDF-S, and I'm getting a bit confused on the datatypes.
 
  Here's my RDF-S:
 
<rdfs:Class rdf:ID="Circle"/>
<rdf:Property rdf:ID="radius">
  <rdfs:domain rdf:resource="#Circle"/>
  <rdfs:range rdf:resource="http://www.w3.org/2001/XMLSchema#integer"/>
</rdf:Property>
<rdfs:Datatype rdf:about="http://www.w3.org/2001/XMLSchema#integer"/>
 
  Here's my RDF:
 
<!-- geometricShapes is assigned to the URI of the RDF-S above -->
<geometricShapes:Circle rdf:ID="sampleCircle">
  <geometricShapes:radius><xmls:integer>23</xmls:integer></geometricShapes:radius>
</geometricShapes:Circle> 
  
  Is this correct?  Is there a reccommended tool/library that I can use to validate RDF against a given RDF-S (Java preferred)?
 
  - Matt