I'm working on how to automatically instantiate an ontology with Jena. I'm interested in instantiating concepts discovered from a set of data. 

My problem is that sometimes I need just to instantiate one concept of the ontology. And I'm confused since in Jena, we need a complete Statement to instantiate an ontology.

Assuming that I've the following ontology.

![enter image description here](https://i.stack.imgur.com/8G9Ce.png)

What would be the statement to instantiate only one concept on the ontology for example `EventType`?

Is it necessary to have a `Statement` to instantiate an ontology ?

or Is my ontology not expressive enough ?

**Edition : My Jena Code**

```
public static void manageOntologies() throws FileNotFoundException{     

    int i,inFrame, lineSize;
    int frameNum = 0;

    Individual individu;
    Resource   resource;
    Statement  statement;
    OntModel   domainModel;

    Vector<String> lines = readFile("data/Trace.dat");

    String[] parts = null;
    String   event = null;

    domainModel = ModelFactory.createOntologyModel(ProfileRegistry.OWL_DL_LANG);
    domainModel.read((new FileInputStream(ontopath)), null);

    lineSize = lines.size(); 

    for(i = 0; i < lineSize; i++){
        parts = lines.elementAt(i).split(" ");
        event = parts[parts.length - 1];            
        resource = domainModel.createResource(xmlbase + "frame" + frameNum);//, domainModel.getOntClass(xmlbase + "Event"));
        domainModel.add(resource, RDF.type, domainModel.getOntClass("Event"));

    }

    System.out.println("Numbre de frame = " + frameNum);

    domainModel.write(System.out);
}

```

And here are is problem encountered

```
Exception in thread "main" java.lang.NullPointerException
    at com.hp.hpl.jena.rdf.model.impl.ModelCom.add(ModelCom.java:929)
    at soctrace.Intology.manageOntologies(Intology.java:87) -- domainModel.add(...)
    at soctrace.Intology.main(Intology.java:38)

```

**Edition 2 : My OWL/XML Code**

```
<?xml version="1.0"?>
<!DOCTYPE rdf:RDF [
    <!ENTITY xsd "http://www.w3.org/2001/XMLSchema#" >
    <!ENTITY rdfs "http://www.w3.org/2000/01/rdf-schema#" >
    <!ENTITY rdf "http://www.w3.org/1999/02/22-rdf-syntax-ns#" >
    <!ENTITY tima "http://www.soctrace.org/ontologies/tima.owl#" >
]>

<rdf:RDF xmlns="http://www.w3.org/2002/07/owl#"
     xml:base="http://www.w3.org/2002/07/owl"
     xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
     xmlns:tima="http://www.soctrace.org/ontologies/tima.owl#"
     xmlns:xsd="http://www.w3.org/2001/XMLSchema#"
     xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
    <Ontology rdf:about="http://www.soctrace.org/ontologies/tima.owl">       
</Ontology>

<!-- http://www.soctrace.org/ontologies/tima.owl#Event -->

<Class rdf:about="&tima;Event">
    <rdfs:subClassOf rdf:resource="http://www.w3.org/2002/07/owl#Thing"/>
</Class>

<!-- http://www.soctrace.org/ontologies/tima.owl#EventDuration -->

<Class rdf:about="&tima;EventDuration">
    <rdfs:subClassOf rdf:resource="&tima;ValuePartition"/>
</Class>

<!-- http://www.soctrace.org/ontologies/tima.owl#EventType -->

<Class rdf:about="&tima;EventType">
    <rdfs:subClassOf rdf:resource="&tima;ValuePartition"/>
</Class>

<!-- http://www.soctrace.org/ontologies/tima.owl#ValuePartition -->

    <Class rdf:about="&tima;ValuePartition"/>
</rdf:RDF>

```

Thanks for any reply !