in commons-rdf-examples/src/example/IntroToRDF.java [28:146]
public static void main(String[] args) {
RDF rdf = new SimpleRDF();
IRI alice = rdf.createIRI("Alice");
System.out.println(alice.ntriplesString());
IRI knows = rdf.createIRI("knows");
IRI bob = rdf.createIRI("Bob");
Triple aliceKnowsBob = rdf.createTriple(alice, knows, bob);
System.out.println(aliceKnowsBob.getSubject().ntriplesString());
System.out.println(aliceKnowsBob);
Graph graph = rdf.createGraph();
graph.add(aliceKnowsBob);
IRI charlie = rdf.createIRI("Charlie");
IRI plays = rdf.createIRI("plays");
IRI football = rdf.createIRI("Football");
IRI tennis = rdf.createIRI("Tennis");
graph.add(alice, knows, charlie);
graph.add(alice, plays, tennis);
graph.add(bob, knows, charlie);
graph.add(bob, plays, football);
graph.add(charlie, plays, tennis);
System.out.println("Who plays Tennis?");
for (Triple triple : graph.iterate(null, plays, tennis)) {
System.out.println(triple.getSubject());
System.out.println(plays.equals(triple.getPredicate()));
System.out.println(tennis.equals(triple.getObject()));
}
System.out.println("Who does Alice know?");
for (Triple triple : graph.iterate(alice, knows, null)) {
System.out.println(triple.getObject());
}
System.out.println("Does Alice anyone that plays Football?");
for (Triple triple : graph.iterate(alice, knows, null)) {
RDFTerm aliceFriend = triple.getObject();
if (! (aliceFriend instanceof BlankNodeOrIRI)) {
continue;
}
if (graph.contains( (BlankNodeOrIRI)aliceFriend, plays, football)) {
System.out.println("Yes, it is " + aliceFriend);
}
}
Literal aliceName = rdf.createLiteral("Alice W. Land");
IRI name = rdf.createIRI("name");
graph.add(alice, name, aliceName);
Optional<? extends Triple> nameTriple = graph.stream(alice, name, null).findAny();
if (nameTriple.isPresent()) {
System.out.println(nameTriple.get());
}
graph.stream(alice, name, null)
.findAny().map(Triple::getObject)
.filter(obj -> obj instanceof Literal)
.map(literalName -> ((Literal)literalName).getLexicalForm())
.ifPresent(System.out::println);
IRI playerRating = rdf.createIRI("playerRating");
Literal aliceRating = rdf.createLiteral("13.37", Types.XSD_FLOAT);
graph.add(alice, playerRating, aliceRating);
Literal footballInEnglish = rdf.createLiteral("football", "en");
Literal footballInNorwegian = rdf.createLiteral("fotball", "no");
graph.add(football, name, footballInEnglish);
graph.add(football, name, footballInNorwegian);
Literal footballInAmericanEnglish = rdf.createLiteral("soccer", "en-US");
graph.add(football, name, footballInAmericanEnglish);
BlankNode someone = rdf.createBlankNode();
graph.add(charlie, knows, someone);
graph.add(someone, plays, football);
BlankNode someoneElse = rdf.createBlankNode();
graph.add(charlie, knows, someoneElse);
for (Triple heKnows : graph.iterate(charlie, knows, null)) {
if (! (heKnows.getObject() instanceof BlankNodeOrIRI)) {
continue;
}
BlankNodeOrIRI who = (BlankNodeOrIRI)heKnows.getObject();
System.out.println("Charlie knows "+ who);
for (Triple whoPlays : graph.iterate(who, plays, null)) {
System.out.println(" who plays " + whoPlays.getObject());
}
}
// Delete previous BlankNode statements
graph.remove(null,null,someone);
graph.remove(someone,null,null);
// no Java variable for the new BlankNode instance
graph.add(charlie, knows, rdf.createBlankNode("someone"));
// at any point later (with the same RDF instance)
graph.add(rdf.createBlankNode("someone"), plays, football);
for (Triple heKnows : graph.iterate(charlie, knows, null)) {
if (! (heKnows.getObject() instanceof BlankNodeOrIRI)) {
continue;
}
BlankNodeOrIRI who = (BlankNodeOrIRI)heKnows.getObject();
System.out.println("Charlie knows "+ who);
for (Triple whoPlays : graph.iterate(who, plays, null)) {
System.out.println(" who plays " + whoPlays.getObject());
}
}
}