this my code
package testowl;

import java.io.File;
import java.net.URI;
import java.net.URL;
import java.util.Set;

import org.semanticweb.HermiT.Reasoner;
import org.semanticweb.owlapi.apibinding.OWLManager;
import org.semanticweb.owlapi.model.IRI;
import org.semanticweb.owlapi.model.OWLAnnotationSubject;
import org.semanticweb.owlapi.model.OWLClass;
import org.semanticweb.owlapi.model.OWLDataFactory;
import org.semanticweb.owlapi.model.OWLEntity;
import org.semanticweb.owlapi.model.OWLIndividual;
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.reasoner.NodeSet;
import org.semanticweb.owlapi.reasoner.OWLReasoner;
import org.semanticweb.owlapi.reasoner.OWLReasonerFactory;
import org.semanticweb.owlapi.reasoner.structural.StructuralReasonerFactory;
import org.semanticweb.owlapi.util.OWLEntityRemover;

public class myclass {
static OWLOntology myOntology ;
static OWLDataFactory df ;
static OWLOntologyManager manager ;
static IRI ontologyIRI ;
static File file = new File("C:/travel.owl");
private OWLOntologyManager manager2;
private static OWLOntology ontology;
private static OWLDataFactory factory;
private static Reasoner reasoner;
private OWLEntityRemover remover;
private static URL url;
private static URI uri;
public static IRI fileURI = IRI.create(file);
static OWLReasonerFactory reasonerFactory = new StructuralReasonerFactory();

    @SuppressWarnings("deprecation")
	public static void main(String args[]) throws OWLOntologyCreationException {
                                   
            manager = OWLManager.createOWLOntologyManager(); 
            myOntology = manager.loadOntology(fileURI);
            ontologyIRI = IRI.create("the IRI of the onology"); 
            df = manager.getOWLDataFactory();	
            System.out.println("Loading Ontology...\n"  + myOntology);
            System.out.println("-----------------------");  
            OWLAnnotationSubject enitity =fileURI;
            System.out.println("all classes for travel antology"+ myOntology.getClassesInSignature());
            Set<OWLClass> entity=myOntology.getClassesInSignature();
            for (OWLClass c : myOntology.getClassesInSignature()) {
                if (c.getIRI().getFragment().equals("Places")){
                	System.out.println("ASDAS");
                    NodeSet<OWLNamedIndividual> instances = reasoner.getInstances(c, false);
                    System.out.println("ASDYYY"+instances);
                    System.out.println("$%$#%$%"+c.getIRI().getFragment());
                    for (OWLNamedIndividual i : instances.getFlattened()) {
                        System.out.println(i.getIRI().getFragment()); 
                    }
                }
            }
     //     System.out.println("all classes "+OWLEntity.getIRI().getShortForm());
           
                              }
             
     
   
 }

i have problem with null pointer exception
i need explore Places from http://www.travel.com/ontologies/travel.owl#Places
that's my owl file