Issues to list classes and subclasses with Jena

Hi Debbie,

You seem to calling hasSubClass() on a different class object to listSubClasses(). Depending on what data you have in your model, essaClasse might have no subclasses, whereas cla does.

Is this deliberate? ...hard to tell since I don't know what data you have in your model, but you seem to be changing the namespace of the class? In that case, you should do so before the hasSubClass() call:

           while (classes.hasNext()) {
                OntClass essaClasse = (OntClass) classes.next();
                String vClasse = essaClasse.getLocalName().toString();

//change namespaces here
                OntClass cla = inf.getOntClass(URI + vClasse);

//call hasSubClass on new class
                if (cla.hasSubClass()) {
                    System.out.println("Classe: " + cla);

for (Iterator i = cla.listSubClasses(); i.hasNext();) {
                        OntClass c = (OntClass) i.next();
                        System.out.print("   " + c.getLocalName() + " " + "\n");
                    }
                }
            }

...alternatively, instead of changing namespaces, you could just check each class to see if it corresponds with the URI namespace.

I didn't have your data file, so I created one and with just a few changes it seems to work. I think the big thing is that you did not have a null pointer check for variable cla.

Code is at: https://gist.github.com/916880

Output with the schema I used:

 Classe: Person
   Brother 
   Parent 
   Uncle 
Classe: Parent
Classe: Brother
Classe: Uncle

As @Signified says you can achieve the same thing without having to specify a new fully qualified URI for the class. This seems like test code, so I thought maybe you were doing with the fully qualified URI to show yourself how it works. But, if you just want to see classes with subclasses then a more succinct version would look like:

import com.hp.hpl.jena.ontology.OntClass;
import com.hp.hpl.jena.ontology.OntModel;
import com.hp.hpl.jena.rdf.model.ModelFactory;
import com.hp.hpl.jena.util.FileManager;
import com.hp.hpl.jena.util.iterator.ExtendedIterator;
import java.io.InputStream;
import java.util.Iterator;

public class TesteProp {

    static final String inputFileName = "schema.owl";

    public static void main(String args[]) {
        try {
            //create the reasoning model using the base
            OntModel inf = ModelFactory.createOntologyModel();

            // use the FileManager to find the input file
            InputStream in = FileManager.get().open(inputFileName);
            if (in == null) {
                throw new IllegalArgumentException("File: " + inputFileName + " not found");
            }

            inf.read(in, "");

            ExtendedIterator classes = inf.listClasses();
            while (classes.hasNext()) {
                OntClass essaClasse = (OntClass) classes.next();

                System.out.println("Classe: " + essaClasse.getLocalName());
                for (Iterator i = essaClasse.listSubClasses(); i.hasNext();) {
                    OntClass c = (OntClass) i.next();
                    System.out.print("   " + c.getLocalName() + "\n");
                } // end for
            }
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}