can not get the subclasses and instances of word ontology

Question

I want to implement an ontology of Word that includes three sub classes: I tried to load the ontology from a file, but I can not fetch the subclasses of a Word and all the instances of a specified subclass. My code looks like this:

import java.util.Iterator;

import org.semanticweb.owlapi.apibinding.OWLManager;
import org.semanticweb.owlapi.io.SystemOutDocumentTarget;
import org.semanticweb.owlapi.model.IRI;
import org.semanticweb.owlapi.model.OWLClass;
import org.semanticweb.owlapi.model.OWLClassAssertionAxiom;
import org.semanticweb.owlapi.model.OWLDataFactory;
import org.semanticweb.owlapi.model.OWLNamedIndividual;
import org.semanticweb.owlapi.model.OWLOntology;
import org.semanticweb.owlapi.model.OWLOntologyCreationException;
import org.semanticweb.owlapi.model.OWLOntologyManager;
import org.semanticweb.owlapi.model.OWLOntologyStorageException;
import org.semanticweb.owlapi.model.PrefixManager;
import org.semanticweb.owlapi.util.AutoIRIMapper;
import org.semanticweb.owlapi.util.DefaultPrefixManager;
import com.hp.hpl.jena.ontology.OntClass;
import com.hp.hpl.jena.ontology.OntModel;
import com.hp.hpl.jena.ontology.OntModelSpec;
import com.hp.hpl.jena.ontology.OntResource;
import com.hp.hpl.jena.rdf.model.ModelFactory;
import com.hp.hpl.jena.util.FileManager;

public class Main {
    public static OWLOntologyManager create() {
        OWLOntologyManager m = OWLManager.createOWLOntologyManager();
       // PriorityCollection<OWLOntologyIRIMapper> iriMappers =              m.getIRIMappers();

  // iriMappers.add(new AutoIRIMapper(new File("materializedOntologies"), true));
        return m;
    }
    public static void main(String[] args) throws OWLOntologyCreationException, OWLOntologyStorageException {
        // Get hold of an ontology manager
        OWLOntologyManager manager = OWLManager.createOWLOntologyManager();
        // Load an ontology from the Web
        IRI iri = IRI.create("http://anywhere");
        OWLOntology pizzaOntology = `manager.loadOntologyFromOntologyDocument(iri);`
        System.out.println("Loaded ontology: " `enter code here`+ WordOntology);
        manager.removeOntology(WordOntology);
        File file = new File("word.owl");
        OWLDataFactory dataFactory = manager.getOWLDataFactory();

        PrefixManager pm = new DefaultPrefixManager(base);
        OWLClass Word = dataFactory.getOWLClass(":Word", pm);
        OWLNamedIndividual Software =                          `dataFactory.getOWLNamedIndividual(":Software", pm);`
        OWLClassAssertionAxiom classAssertion =              
dataFactory.getOWLClassAssertionAxiom(Word, Software);
        OWLOntology ontology = manager.createOntology(IRI.create(base));
        manager.addAxiom(ontology, classAssertion);
        manager.saveOntology(ontology, new SystemOutDocumentTarget());
        OWLOntologyManager m = create();
        OWLOntology o = m.loadOntologyFromOntologyDocument(iri);
        assertNotNull(o);
        OWLDataFactory factory = manager.getOWLDataFactory();
        for (OWLClass cls : o.getClassesInSignature())
        System.out.println(cls);
        }
     }

Answer 1

OWLOntology::getSubClassAxiomsForSuperClass(OWLClass) will return the subclass axioms where the specified class is the superclass - the subclass in the axiom will be a subclass of Word in your example.

OWLOntology::getClassAssertionAxioms(OWLClass) returns class assertions with the specified class - the individuals in these axioms will be the instances of Word.

Note that these methods only return data that is explicit in the ontology; for finding data that can be inferred, you need to use an OWLReasoner. Proper implementations of OWLReasoner exist outside the OWLAPI, see for example Pellet, HermiT, FaCT++, Konclude, JFact (Open Source) and StarDog (commercial licence).