Maybe there are no results.
This is not a complete, minimal example. Unseen details probably matter.
Andy
On 09/01/17 13:28, javed khan wrote:
Hello Lorenz, yes I need student and highscore.
I just tried this , no exception but it does not display the message in
JOptionPane.showMessageDialog()
Query query2 = QueryFactory.create(queryString2);
QueryExecution qexec = QueryExecutionFactory.create(query2, model) ;
ResultSet results2 = qexec.execSelect() ;
RDFNode r;
while(results2.hasNext()){
QuerySolution sol= results2.nextSolution();
r=sol.get("student");
JOptionPane.showMessageDialog(null,"high score is" + r );
}
On Mon, Jan 9, 2017 at 1:42 PM, Lorenz Buehmann <
[email protected]> wrote:
@ As per the previous discussion, I guess he also wants to have the
student - and of course the highest score,
As Chris said, you have to distinguish between literals and URIs/blank
nodes.
Which finally leads me to the suggestion to read an RDF tutorial +
SPARQL tutorial first. Most questions are really basic.
On 09.01.2017 09:38, Chris Dollin wrote:
On 08/01/17 18:32, javed khan wrote:
This query gives me exception:
Exception in thread "AWT-EventQueue-0"
com.hp.hpl.jena.rdf.model.LiteralRequiredException:
http://www.semanticweb.org/t/ontologies#Smith
"SELECT * " +
" WHERE {" + " {"+ "select (max(?score) as
?highScore)"
+ " { ?student std:Englishscore ?score" +
" }" +
" } " +
"?student std:Englishscore ?highScore" +
"}";
The variable ?subject will be the subject of a triple.
Subjects may be blank nodes or resources with URIs.
Query query2 = QueryFactory.create(queryString2);
QueryExecution qexec = QueryExecutionFactory.create(query2, model) ;
ResultSet results2 = qexec.execSelect() ;
Literal l2=results2.next().get("student").asLiteral();
get("student") will return the value of "student", which will
be a resource or blank node, but NOT a literal. asLiteral
expects a Literal.
BOOM.
My pre-caffeine guess is that you want "highscore" not "student".
As others have said, offer complete minimal examples.
Chris
