中文XML论坛--我修改了程序，用jena+racer推理总是随机的

贴子主题：我修改了程序，用jena+racer推理总是随机的

本主题类别: Ontology Language | Description Logics

我根据jpz6311whu大侠的指导，更改了程序如下：
public static void main( String[] args )  {
    // set up a configuration resource to connect to the reasoner
    // on port 2004 on the local system
   Model cModel = ModelFactory.createDefaultModel();
     Resource conf = cModel.createResource();
     conf.addProperty( ReasonerVocabulary.EXT_REASONER_URL,
                       cModel.createResource( "http://localhost:8080" ) );
  DIGReasonerFactory drf = (DIGReasonerFactory) ReasonerRegistry.theRegistry().getFactory(DIGReasonerFactory.URI);
  DIGReasoner r = (DIGReasoner) drf.create(conf);

// System.out.println("sdfsdf");

    // now make a model
    OntModelSpec spec = new OntModelSpec( OntModelSpec.OWL_DL_MEM );
    spec.setReasoner( r );
    OntModel m = ModelFactory.createOntologyModel( spec, null );


    m.read("file:///c:/newAnimal.owl");

    for (Iterator i = m.listClasses(); i.hasNext();) {//输出他们的父类
        OntClass c = (OntClass) i.next();
        for (Iterator it = c.listSuperClasses(); it.hasNext();)

{

OntClass sp = (OntClass) it.next();

String str = c.getModel().getGraph()

.getPrefixMapping().shortForm(c.getURI()) // 获取URI

+ "'s superClass is " ;

String strSP = sp.getURI();

try{
str = str + ":" + strSP.substring(strSP.indexOf('#')+1);

System.out.println(" Class" +str);

}catch( Exception e ){}

}

    }
得到的结果是随机的，就是说有时候推出来了，有时候就提示错误：
Class:Herbivore's superClass is :Animal
     Class:Leaf's superClass is :Plant
     Class:Lion's superClass is :Carnivore
     Class:Lion's superClass is :Animal
Exception in thread "main" java.lang.NullPointerException
at com.hp.hpl.jena.shared.impl.PrefixMappingImpl.findMapping(PrefixMappingImpl.java:235)
at com.hp.hpl.jena.shared.impl.PrefixMappingImpl.shortForm(PrefixMappingImpl.java:214)
at com.hp.hpl.jena.graph.compose.PolyadicPrefixMappingImpl.shortForm(PolyadicPrefixMappingImpl.java:146)
at DIGExample.main(DIGExample.java:53)
这是结果，最后总体是错误 java.lang.NullPointerException。不知道为什么，请提示一下


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