rdf - Jena: property name cannot be resolved to a variable? -


i'm using jena query ontology, , i'm following step 8: querying model of this tutorial. rdf file vc-db-1.rdf being queried here generated step 3: writing rdf , shown below:

<rdf:rdf     xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"     xmlns:vcard="http://www.w3.org/2001/vcard-rdf/3.0#" >    <rdf:description rdf:nodeid="a0">     <vcard:family>smith</vcard:family>     <vcard:given>john</vcard:given>   </rdf:description>   <rdf:description rdf:about="http://somewhere/johnsmith">     <vcard:n rdf:nodeid="a0"/>     <vcard:fn>john smith</vcard:fn>   </rdf:description> </rdf:rdf>

the sample code tutorial 7 , can downloaded here.

i noticed in line

resiterator iter = model.listresourceswithproperty(vcard.fn);

vcard.fn property name rdf, not defined variable in code. however, can recognized here , code runs without problem.

but not case own rdf file. created ontology pottery.owl protege , saved in rdf/xml language. file content followed:

<?xml version="1.0"?> <rdf:rdf     xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"     xmlns:protege="http://protege.stanford.edu/plugins/owl/protege#"     xmlns:xsp="http://www.owl-ontologies.com/2005/08/07/xsp.owl#"     xmlns:owl="http://www.w3.org/2002/07/owl#"     xmlns:xsd="http://www.w3.org/2001/xmlschema#"     xmlns:swrl="http://www.w3.org/2003/11/swrl#"     xmlns="http://www.owl-ontologies.com/ontology1369190090.owl#"     xmlns:swrlb="http://www.w3.org/2003/11/swrlb#"     xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"   xml:base="http://www.owl-ontologies.com/ontology1369190090.owl" >    <rdf:description rdf:about="">     <rdf:type rdf:resource="http://www.w3.org/2002/07/owl#ontology"/>   </rdf:description>   <rdf:description rdf:about="#pottery">     <rdf:type rdf:resource="http://www.w3.org/2002/07/owl#class"/>   </rdf:description>   <rdf:description rdf:about="#pottery_instance_1">     <rdf:type rdf:resource="#pottery"/>     <pottery.colors rdf:datatype="http://www.w3.org/2001/xmlschema#string">blue</pottery.colors>   </rdf:description>   <rdf:description rdf:about="#pottery.colors">     <rdf:type rdf:resource="http://www.w3.org/2002/07/owl#datatypeproperty"/>     <rdfs:range rdf:resource="http://www.w3.org/2001/xmlschema#string"/>     <rdfs:domain rdf:resource="#pottery"/>   </rdf:description> </rdf:rdf>  <!-- created protege (with owl plugin 3.4.8, build 629)  http://protege.stanford.edu -->

the ontology contains class pottery, instance pottery_instance_1, , datatype property pottery.colors.

and modified these lines in original code:

static final string inputfilename = "pottery.owl"; // ... resiterator iter = model.listresourceswithproperty(pottery.colors); // ... system.out.println("  " + iter.nextresource()                               .getproperty(pottery.colors)                               .getstring());

this time got error "pottery cannot resolved variable."

what's trick here? have difference between formats of 2 rdfs? or else? thank you.

vcard java class define in package com.hp.hpl.jena.vocabulary. contains java constants items in (now, old) vcard vocabulary.

if want generate own class ontology, @ schemagen application shipped jena.


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