As Dave said, wrong PREFIX declaration.
>>
>> "Select *" + "where { ?x rdf:type std:StudentExpert }";
>>
Moreover, your String concatenation will lead to
Select *where { ?x rdf:type std:StudentExpert }
i.e. there is a missing whitespace before "where".
--
Lorenz Bühmann
AKSW group, University of Leipzig
Group: http://aksw.org - semantic web research center
