SPARQL query using Jena producing no results — but works online

Question

Basically I have the following query, and it works in all the online SPARQL testers without a problem, but when using Java and Jena 2.6.4, I never get any results. I've written the values into the query for demonstration purposes.

PREFIX  g:    <http://www.w3.org/2003/01/geo/wgs84_pos#>
PREFIX  rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX  onto: <http://dbpedia.org/ontology/>

SELECT  ?subject ?stadium ?lat ?long
WHERE
  { ?subject g:lat ?lat .
    ?subject g:long ?long .
    ?subject <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> onto:Stadium .
    ?subject rdfs:label ?stadium
    FILTER ( ( ( ( ( ?lat >= 52.4814 ) && ( ?lat <= 57.4814 ) ) && ( ?long >= -1.89358 ) ) && ( ?long <= 3.10642 ) ) && ( lang(?stadium) = "en" ) )
  }
LIMIT   5

Some Java, note I've tried accessing this a few different ways, however I'm using SPARQL throughout the project and have no problems.

Query query = QueryFactory.create(s2); //s2 = the query above
QueryExecution qExe = QueryExecutionFactory.create(query, model);
ResultSet resultsRes = qExe.execSelect();

try {
  while (resultsRes.hasNext()) {                
    QuerySolution soln = resultsRes.nextSolution();
    //never any results
  }
} catch (Exception ex) {
  System.out.println(ex);
}

Kattegat

Just tried the SPARQL against dbpedia.org via Virtuoso endpoint and got results. However, what isn't clear from your code is how the SPARQL query is assigned to s2 and how the data gets into the model. – Yahiya

Answer 1

Unless you are loading the entire DBpedia dataset into a local model, to get the same effect as running the query in the DBpedia SPARQL form you will have to send your query to the DBpedia SPARQL end point. I ran the following modification of your program:

package example;

import com.hp.hpl.jena.query.*;

public class AshTest
{
    public static void main( String[] args ) {
        String s2 = "PREFIX  g:    <http://www.w3.org/2003/01/geo/wgs84_pos#>\n" +
                "PREFIX  rdfs: <http://www.w3.org/2000/01/rdf-schema#>\n" +
                "PREFIX  onto: <http://dbpedia.org/ontology/>\n" +
                "\n" +
                "SELECT  ?subject ?stadium ?lat ?long\n" +
                "WHERE\n" +
                "  { ?subject g:lat ?lat .\n" +
                "    ?subject g:long ?long .\n" +
                "    ?subject <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> onto:Stadium .\n" +
                "    ?subject rdfs:label ?stadium\n" +
                "    FILTER ( ( ( ( ( ?lat >= 52.4814 ) && ( ?lat <= 57.4814 ) ) && ( ?long >= -1.89358 ) ) && ( ?long <= 3.10642 ) ) && ( lang(?stadium) = \"en\" ) )\n" +
                "  }\n" +
                "LIMIT   5\n" +
                "";

        Query query = QueryFactory.create(s2); //s2 = the query above
        QueryExecution qExe = QueryExecutionFactory.sparqlService( "http://dbpedia.org/sparql", query );
        ResultSet results = qExe.execSelect();
        ResultSetFormatter.out(System.out, results, query) ;
    }
}

and got the following result:

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| subject                                                       | stadium                              | lat                                                 | long                                                  |
======================================================================================================================================================================================================================
| <http://dbpedia.org/resource/Welford_Road_Stadium>            | "Welford Road Stadium"@en            | "52.6242"^^<http://www.w3.org/2001/XMLSchema#float> | "-1.13306"^^<http://www.w3.org/2001/XMLSchema#float>  |
| <http://dbpedia.org/resource/Hillsborough_Stadium>            | "Hillsborough Stadium"@en            | "53.4114"^^<http://www.w3.org/2001/XMLSchema#float> | "-1.50056"^^<http://www.w3.org/2001/XMLSchema#float>  |
| <http://dbpedia.org/resource/Gateshead_International_Stadium> | "Gateshead International Stadium"@en | "54.9611"^^<http://www.w3.org/2001/XMLSchema#float> | "-1.57972"^^<http://www.w3.org/2001/XMLSchema#float>  |
| <http://dbpedia.org/resource/Filbert_Street>                  | "Filbert Street"@en                  | "52.6236"^^<http://www.w3.org/2001/XMLSchema#float> | "-1.14056"^^<http://www.w3.org/2001/XMLSchema#float>  |
| <http://dbpedia.org/resource/Craven_Park,_Hull>               | "Craven Park, Hull"@en               | "53.7539"^^<http://www.w3.org/2001/XMLSchema#float> | "-0.264722"^^<http://www.w3.org/2001/XMLSchema#float> |
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Shigella

Yeah I tried that approach but it didn't work, after copy pasting that example without results, I deleted all the import statements and that fixed the issue. Thanks so much :) – Kattegat