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I'm trying to run SPARQL queries on my self-made ontology in protege, I have stored the data in TDB persistent storage and so far I assume that data is being successfully stored in it. I have run several SPARQL queries of the same ontology file in Jena Fuseki and all of them are working, but unfortunately, whenever I try to run the same SPARQL queries over this dataset it shows me the null value error as shown in the question above. I would really appreciate if anyone helps me in this matter and be very specific as I'm relatively new and very inexperienced in the field of semantic web. following is the code of my TDB file.

 package jena;

 import java.util.Iterator;

 import org.apache.jena.query.Dataset;
 import org.apache.jena.query.Query;
 import org.apache.jena.query.QueryExecution;
 import org.apache.jena.query.QueryExecutionFactory;
 import org.apache.jena.query.QueryFactory;
 import org.apache.jena.query.ResultSet;
 import org.apache.jena.query.ResultSetFormatter;
 import org.apache.jena.rdf.model.*;
 import org.apache.jena.tdb.TDB;
 import org.apache.jena.util.FileManager;

 import com.hp.hpl.jena.query.QuerySolution;
 import com.hp.hpl.jena.rdf.model.Literal;
 import com.hp.hpl.jena.tdb.TDBFactory;
 //import com.hp.hpl.jena.util.FileManager;

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


new tdb().storetdbdata();
    new tdb().loadtdbdata();
    new tdb().viasparql();
}

public void storetdbdata()
{
    String directory = "c:/users/shahrukh/databases";
    Dataset dataset = TDBFactory.createDataset(directory);
    Model tdb = dataset.getDefaultModel();
    //Model tdb = dataset.getNamedGraph( "graph42" );
    String source ="e:/university work/fyp/sdd folder/my sdd/university.owl";
    FileManager.get().loadModel(source);
    //FileManager.get().readModel( tdb, source);
    //dataset.commit();
    TDB.sync(dataset);
    tdb.close();
    dataset.close();


    }


public void loadtdbdata()
{
    String directory = "c:/users/shahrukh/databases";
    Dataset dataset = TDBFactory.createDataset(directory) ;
    Iterator<String> graphNames = dataset.listNames();
    while (graphNames.hasNext()) {
        String graphName = graphNames.next();
        System.out.println(graphName);
    }

}
public void viasparql()
{
    String directory = "c:/users/shahrukh/databases" ;
    Dataset dataset = TDBFactory.createDataset(directory) ;

    String sparqlQueryString = "SELECT (count(*) AS ?count) { ?s ?p ?o }" ;
    /*String sparqlQueryString="PREFIX st: <http://www.semanticweb.org/shahrukh/ontologies/2017/4/university.owl#>"+
            "PREFIX foaf: <http://www.semanticweb.org/shahrukh/ontologies/2017/4/university.owl#>"+
            "PREFIX rdf: <http://www.semanticweb.org/shahrukh/ontologies/2017/4/university.owl#>" +
            "SELECT ?y  WHERE { <http://www.semanticweb.org/shahrukh/ontologies/2017/4/university.owl#JawadMirza> rdf:first_name ?y. }";*/
    //String sparqlQueryString="SELECT *";
    //String sparqlQueryString="SELECT * { GRAPH ?g {} }";
    String s2="PREFIX st: <http://www.semanticweb.org/shahrukh/ontologies/2017/4/university.owl#>" +
    "SELECT ?first_name ?last_name  WHERE { ?x st:first_name ?first_name ."
    + "?x st:last_name ?last_name" + "}";

    String s="prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>" +
    "prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>" +
    "prefix owl: <http://www.w3.org/2002/07/owl#>" +
    "prefix xsd: <http://www.w3.org/2001/XMLSchema#>" +
    "SELECT ?s ?p ?o WHERE { ?s ?p ?o }";
    String s3="SELECT ?s ?p ?o WHERE {?s HAS+ ?o FILTER ( ?s = <ID_6> )} ";

    Query query = QueryFactory.create(s) ;
    QueryExecution qexec = QueryExecutionFactory.create(query, dataset) ;
    QueryExecution qExe = QueryExecutionFactory.sparqlService( "http://10.0.2.2:3030/dataset.html?tab=upload&ds=/FYP", query );
    ResultSet results = qexec.execSelect() ;
    /*while (results.hasNext()) {                
        QuerySolution soln = (QuerySolution) results.nextSolution();
    }*/
    /*org.apache.jena.query.QuerySolution soln=results.nextSolution();
    Literal first_name=(Literal) soln.getLiteral("?s");
    System.out.println(first_name);*/
    ResultSetFormatter.out(System.out,results,query) ;
    }
}

Following are the exceptions I have been receiving:

     WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
 WARN [main] (Log.java:80) - Binding.add: null value - ignored
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Shahrukh Nasir
  • 131
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  • Start with adhering to java naming conventions. Method names go camelCase() - and you don't use _ in variable names. – GhostCat Sep 12 '17 at 06:59
  • 1
    You're mixing two totally different Jena versions: you have classes from packages `com.hp.hpl.jena.` which is the old Jena 2.x and others from package `org.apache.jena.` which indicates Jena 3.x - that will **not** work – UninformedUser Sep 12 '17 at 08:30
  • 1
    And showing an error without the stacktrace and the line in which it occurs in your code makes anything else impossible. But first, fix the version issue - latest Jena is **3.4.0** - don't use older versions if there is no good reason for. – UninformedUser Sep 12 '17 at 08:34

0 Answers0