TDB Jena Querying - sparql

Question

I am trying to query in Java with Jena using TDB. So basically i got an n3 file name song.n3 and using this file I want to use this with TDB. So I have created a directory which is generated in my Java1 folder (Netbeans project folder) and then I have the source of the actual n3 file. After running this code I am having the error "java.lang.NoClassDefFoundError". Basically debugging the code lead to the error being caused by the line : Dataset dataset = TDBFactory.createDataset(directory);. I am not too sure why this error is caused could it be that it because my directory is empty with no model.
public static void main(String[] args) throws IOException {
String directory = "./tdb";
Dataset dataset = TDBFactory.createDataset(directory);
Model tdb = dataset.getDefaultModel();
String source = "C:\\Users\\Name\\Documents\\NetBeansProjects\\Java1\\src\\song.n3";
FileManager.get().readModel( tdb, source, "N3" );
String queryString = "PREFIX owl: <http://www.w3.org/2002/07/owl#> SELECT * WHERE { ?x owl:sameas ?y }";
Query query = QueryFactory.create(queryString);
QueryExecution qe = QueryExecutionFactory.create(query, tdb);
ResultSet results = qe.execSelect();
ResultSetFormatter.out(System.out, results, query);
qe.close();
}
}

Answer 1

This should be a problem with your CLASSPATH, when I use TDB I have the following script to load the Jena-TDB libraries into my classpath ..
#!/bin/bash
CP="."
for i in ./TDB-0.8.9/lib/*.jar ; do
CP=$CP:./TDB-0.8.9/lib/$i
done
export CLASSPATH=$CP
It is bash but very easy to translate into a Windows script. Bottom line, make sure that all the jars in /lib/ directory are in the CLASSPATH. Anyway, it would help it you give the complete java.lang.NoClassDefFoundError where the class not found is shown, that would give you a hint of what it is missing. Probably some of the logging libs that are not shipped inside the jena distribution.
Also, watch out for that owl:sameas predicate. SPARQL and RDF are case sensitive and the correct predicate is owl:sameAs.