This looks like some system wide initialisation isn’t happening correctly in your runtime environment.
You can first try adding a JenaSystem.init() call as the first line in your main() method Also, if you are building a fat/uber JAR via your build toolchain please be aware that Jena uses ServiceLoader for auto-discovery of system initialisation. Please refer to https://jena.apache.org/documentation/notes/jena-repack.html for notes on how to ensure that doing so doesn’t break things like this. Rob From: Anna P <[email protected]> Date: Monday, 11 March 2024 at 13:45 To: [email protected] <[email protected]> Subject: Problems when querying the SPARQL with Jena Dear Jena support team, Currently I just started to work on a SPARQL project using Jena and I could not get a solution when I query a model. I imported a turtle file and ran a simple query, and the snippet code is shown below. However, I got the error. public class App { public static void main(String[] args) { try { Model model = RDFDataMgr.loadModel('data.ttl', Lang.TURTLE); RDFDataMgr.write(System.out, model, Lang.TURTLE); String queryString = "SELECT * { ?s ?p ?o }"; Query query = QueryFactory.create(queryString); QueryExecution qe = QueryExecutionFactory.create(query, model); ResultSet results = qe.execSelect(); ResultSetFormatter.out(System.out, results, query); qe.close(); } catch (Exception e) { e.printStackTrace(); } } } Here is the error message: org.apache.jena.riot.RiotException: Not registered as a SPARQL result set output syntax: Lang:SPARQL-Results-JSON at org.apache.jena.sparql.resultset.ResultsWriter.write(ResultsWriter.java:179) at org.apache.jena.sparql.resultset.ResultsWriter.write(ResultsWriter.java:156) at org.apache.jena.sparql.resultset.ResultsWriter.write(ResultsWriter.java:149) at org.apache.jena.sparql.resultset.ResultsWriter$Builder.write(ResultsWriter.java:96) at org.apache.jena.query.ResultSetFormatter.output(ResultSetFormatter.java:308) at org.apache.jena.query.ResultSetFormatter.outputAsJSON(ResultSetFormatter.java:516) at de.unistuttgart.ki.esparql.App.main(App.java:46) Thank you for your time and help! Best regards, Pan
