I don't know your code, but please look carefully at the stack trace: at com.mycompany.app.RdfWriter.main(RdfWriter.java:13) Caused by: java.lang.NullPointerException
> at com.mycompany.app.RdfWriter.main(RdfWriter.java:13) > Caused by: java.lang.NullPointerException -- Lorenz Bühmann AKSW group, University of Leipzig Group: http://aksw.org - semantic web research center
