Trying to Remove Individual gives NullPointerException

Question

I try to remove an existing individual from my RDF file, but I always get a NullPointerException. The Individual I am getting is there, because I can print out a property. Can someone please tell me what I have done wrong?

final static String SN = "http://vaceta.pavo.uberspace.de/RDF/social-media.owl#";

InputStream in = context.getResourceAsStream("WEB-INF/resources/social-media.rdf");
OntModel model = ModelFactory.createOntologyModel(OntModelSpec.OWL_MEM);
model.read(in, null);
in.close();

Individual user01 = model.getIndividual(SN + "User01");
model.remove(user01, null, (RDFNode) null);
model.remove(null, null, user01);

output = new FileOutputStream(context.getRealPath("/")+"WEB-INF/resources/social-media.rdf");
model.writeAll(output, "RDF/XML", null);
output.close();

stacktrace:

Answer 1

You're using ModelCon.remove(s,p,o) which doesn't allow nulls. You want to use Model.removeAll(s,p,o) instead which does allow nulls and uses them as wildcards. Here are the corresponding Javadocs (with emphasis added):

ModelCon.remove

Model remove(Resource s, Property p, RDFNode o)

remove the statement (s, p, o) from this model and answer this model. None of s, p, o are permitted to be null: for wildcard removal, see removeAll.

Model.removeAll

Model removeAll(Resource s, Property p, RDFNode r)

Remove all the statements matching (s, p, o) from this model.