Java 引用不正确

Question

我正在使用 OWL-S API(此处的源代码和 javadoc: http://on.cs.unibas.ch/owls-api/apidocs/ )

如果我这样做，我会得到正确的结果:

public class Example {
    private static ISWRLFactory factory; //is a interface
    private string url = "http://...";
    private Service aService;
    private OWLOntology ont;

    void method_A(){
            URI aURI = URI.create(url);
            OWLKnowledgeBase aKB = OWLFactory.createKB();    
            aService = aKB.readService(aURI);
            ont = aKB.createOntology(aURI);
            ont.createService(aService.getURI());

    }

    void method_B(){
    factory = SWRLFactory.createFactory(ont);
    Atom builtAtom = factory.createNotEqual(x, variab); //x and variab are two variable
    }
   }

但是如果我这样做，我不会得到正确的结果:

public class Example {
    private static ISWRLFactory factory; //is a interface
    private string url = "http://...";
    private Service aService;
    private OWLOntology ont;


    void method_A(){
            URI aURI = URI.create(url);
            OWLKnowledgeBase aKB = OWLFactory.createKB();    
            aService = aKB.readService(aURI);
            ont = aKB.createOntology(aURI);
            ont.createService(aService.getURI());
            factory = SWRLFactory.createFactory(ont);
    }

    void method_B(){
    Atom builtAtom = factory.createNotEqual(x, variab); //x and variab are two variable
    }
}

为什么？

Answer 1

执行“factory = SWRLFactory.createFactory(ont);”时存在差异method_A() 和 method_B() 中的行。您确定“工厂”对象在 method_A() 和 method_B() 调用之间没有被修改吗？ “x”和“变量”对“工厂”有一定的依赖性吗？