getting data from owl file in java

Question

i am getting all members of Student .i use the following code but i getting result only ind my query is correct . when i run that query in protege 4.3 they give correct result but problem in java code.i dont understand what i do wrong .please suggest what i wrong in my java class.

class sparql1
    {  public static void main(String[] args) {

            String filename="modified2.owl";
            Model model=ModelFactory.createDefaultModel();
            OntModel model1=ModelFactory.createOntologyModel(OntModelSpec.OWL_DL_MEM);

            try
            {
                File file=new File(filename);
                FileInputStream reader=new FileInputStream(file);
                model.read(reader,null);

                String query1=" PREFIX rdfs:  PREFIX rdf:  PREFIX my:  SELECT  ?ind WHERE { ?ind rdf:type my:Student .}";

                com.hp.hpl.jena.query.Query query=QueryFactory.create(query1);
                QueryExecution exe=QueryExecutionFactory.create(query, model1);
                ResultSet RES=exe.execSelect();
                ResultSetFormatter.out(System.out, RES, query);
            }catch(Exception e)
            {
                e.printStackTrace();
            }
        }
    }

my ontology is

Rob Hall · Accepted Answer

You get no results because you are querying the empty model1 while all of your results are contained in model. Simply change:

OntModel model1=ModelFactory.createOntologyModel(OntModelSpec.OWL_DL_MEM);

... to ...

OntModel model1=ModelFactory.createOntologyModel(OntModelSpec.OWL_DL_MEM, model);

... and then your subsequent query will have access to the triples inside of the OntModel. The proof is found on the line where you create your QueryExecution instance:

QueryExecution exe=QueryExecutionFactory.create(query, model1);

On this line, you create a query that references the new model, which has none of the triples that you read in from your file.

getting data from owl file in java

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