[Pellet-users] Non-deterministic NullPointerException

[John Berryman]

Hello All,

Upon issuing the command: model.writeAll(System.out,null,"RDF/XML- 
ABBREV");

I get the following NullPointerError deep inside of Pellet:

Exception in thread "main" java.lang.NullPointerException
	at  
org 
.mindswap 
.pellet.tableau.completion.SROIQStrategy.backtrack(SROIQStrategy.java: 
56)
	at  
com 
.clarkparsia 
.pellet 
.rules.ContinuousRulesStrategy.complete(ContinuousRulesStrategy.java: 
403)
	at org.mindswap.pellet.ABox.isConsistent(ABox.java:1283)
	at org.mindswap.pellet.ABox.isSatisfiable(ABox.java:567)
	at org.mindswap.pellet.ABox.isSatisfiable(ABox.java:532)
	at org.mindswap.pellet.KnowledgeBase.retrieve(KnowledgeBase.java:3871)
	at org.mindswap.pellet.KnowledgeBase.getInstances(KnowledgeBase.java: 
3165)
	at org.mindswap.pellet.KnowledgeBase.getDifferents(KnowledgeBase.java: 
2854)
	at  
org 
.mindswap 
.pellet.jena.ModelExtractor.extractIndividualModel(ModelExtractor.java: 
466)
	at  
org 
.mindswap.pellet.jena.ModelExtractor.extractModel(ModelExtractor.java: 
519)
	at  
org 
.mindswap.pellet.jena.ModelExtractor.extractModel(ModelExtractor.java: 
513)
	at org.mindswap.pellet.jena.graph.query.GraphQueryHandler 
$1.find(GraphQueryHandler.java:158)
	at  
org 
.mindswap 
.pellet 
.jena.graph.query.GraphQueryHandler.findTriple(GraphQueryHandler.java: 
1527)
	at  
org 
.mindswap 
.pellet.jena.PelletInfGraph.findWithContinuation(PelletInfGraph.java: 
146)
	at  
com.hp.hpl.jena.reasoner.BaseInfGraph.graphBaseFind(BaseInfGraph.java: 
345)
	at  
com.hp.hpl.jena.reasoner.BaseInfGraph.graphBaseFind(BaseInfGraph.java: 
334)
	at com.hp.hpl.jena.graph.impl.GraphBase.find(GraphBase.java:240)
	at  
com 
.hp 
.hpl.jena.graph.compose.DisjointUnion.graphBaseFind(DisjointUnion.java: 
27)
	at com.hp.hpl.jena.graph.impl.GraphBase.find(GraphBase.java:240)
	at com.hp.hpl.jena.graph.impl.GraphBase.graphBaseFind(GraphBase.java: 
260)
	at com.hp.hpl.jena.graph.impl.GraphBase.find(GraphBase.java:257)
	at  
com 
.hp 
.hpl 
.jena 
.graph.query.SimpleQueryHandler.predicatesFor(SimpleQueryHandler.java: 
68)
	at  
com 
.hp 
.hpl 
.jena 
.graph.query.SimpleQueryHandler.predicatesFor(SimpleQueryHandler.java: 
47)
	at  
com.hp.hpl.jena.rdf.model.impl.ModelCom.listPredicates(ModelCom.java: 
761)
	at  
com.hp.hpl.jena.rdf.model.impl.ModelCom.listNameSpaces(ModelCom.java: 
773)
	at  
com 
.hp 
.hpl 
.jena.xmloutput.impl.BaseXMLWriter.addNameSpaces(BaseXMLWriter.java:201)
	at  
com 
.hp 
.hpl 
.jena.xmloutput.impl.BaseXMLWriter.setupNamespaces(BaseXMLWriter.java: 
439)
	at  
com.hp.hpl.jena.xmloutput.impl.BaseXMLWriter.write(BaseXMLWriter.java: 
421)
	at  
com.hp.hpl.jena.xmloutput.impl.BaseXMLWriter.write(BaseXMLWriter.java: 
410)
	at com.hp.hpl.jena.rdf.model.impl.ModelCom.write(ModelCom.java:282)
	at  
com.hp.hpl.jena.ontology.impl.OntModelImpl.writeAll(OntModelImpl.java: 
2592)
	at  
ontology 
.unitTests 
.Implementation.createAndTestImplementation(BascitModelUnitTest.java: 
255)
	at  
ontology.unitTests.BascitModelUnitTest.main(BascitModelUnitTest.java:37)

And perhaps related I am also getting this warning several times:
  WARN [main] (RDFDefaultErrorHandler.java:36) - unknown-source:  
{W136} Relative URIs are not permitted in RDF: specifically <RDF/XML- 
ABBREV>

The strangest thing is that the error appears to be nondeterministic  
because I can make unrelated changes to the code and I will not  
receive this error.  Actually, I've even had the code in the same  
state (after do and undoing changes) and I may or may not get this  
error.

Thoughts?
John
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