Commons RDF user guide - see http://commonsrdf.incubator.apache.org/userguide.html

ExampleTest.java

package com.example.commonsrdf;

import java.nio.charset.Charset;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Optional;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import org.apache.commons.rdf.api.BlankNode;
import org.apache.commons.rdf.api.BlankNodeOrIRI;
import org.apache.commons.rdf.api.Graph;
import org.apache.commons.rdf.api.IRI;
import org.apache.commons.rdf.api.Literal;
import org.apache.commons.rdf.api.RDFTerm;
import org.apache.commons.rdf.api.RDFTermFactory;
import org.apache.commons.rdf.api.Triple;
import org.apache.commons.rdf.simple.SimpleRDFTermFactory;
import org.apache.commons.rdf.simple.Types;
import org.junit.Before;
import org.junit.Test;

public class ExampleTest {

	private RDFTermFactory factory;
	private Triple triple;
	private IRI nameIri;

	@Before
	public void factory() {
		factory = new SimpleRDFTermFactory();
	}

	@Test
	public void creating() throws Exception {
		BlankNode aliceBlankNode = factory.createBlankNode();
		nameIri = factory.createIRI("http://example.com/name");
		Literal aliceLiteral = factory.createLiteral("Alice");
		Triple triple = factory.createTriple(aliceBlankNode, nameIri, aliceLiteral);

		System.out.println(aliceBlankNode.ntriplesString());
		System.out.println(nameIri.ntriplesString());
		System.out.println(aliceLiteral.ntriplesString());

	}

	@Test
	public void ntriples() throws Exception {
		IRI iri = factory.createIRI("http://example.com/alice");
		System.out.println(iri.getIRIString());

		IRI iri2 = factory.createIRI("http://example.com/alice");
		System.out.println(iri.equals(iri2));

		IRI iri3 = factory.createIRI("http://example.com/alice/./");
		System.out.println(iri.equals(iri3));

		System.out.println(iri.equals("http://example.com/alice"));
		System.out.println(iri.equals(factory.createLiteral("http://example.com/alice")));

	}

	@Test
	public void blanknode() throws Exception {
		BlankNode bnode = factory.createBlankNode();
		System.out.println(bnode.equals(bnode));
		System.out.println(bnode.equals(factory.createBlankNode()));

		BlankNode b1 = factory.createBlankNode("b1");

		System.out.println(b1.ntriplesString());

		System.out.println(b1.equals(factory.createBlankNode("b1")));
		System.out.println(b1.equals(new SimpleRDFTermFactory().createBlankNode("b1")));

		System.out.println(bnode.internalIdentifier());
	}

	@Test
	public void literal() throws Exception {
		Literal literal = factory.createLiteral("Hello world!");
		System.out.println(literal.ntriplesString());

		String lexical = literal.getLexicalForm();
		System.out.println(lexical);

		IRI datatype = literal.getDatatype();
		System.out.println(datatype.ntriplesString());

		IRI xsdDouble = factory.createIRI("http://www.w3.org/2001/XMLSchema#double");
		Literal literalDouble = factory.createLiteral("13.37", xsdDouble);
		System.out.println(literalDouble.ntriplesString());

		Literal literalDouble2 = factory.createLiteral("13.37", Types.XSD_DOUBLE);

		System.out.println(literal.getDatatype().equals(Types.XSD_STRING));

		Literal inSpanish = factory.createLiteral("¡Hola, Mundo!", "es");
		System.out.println(inSpanish.ntriplesString());
		System.out.println(inSpanish.getLexicalForm());
		System.out.println(inSpanish.getDatatype().ntriplesString());

		Optional<String> tag = inSpanish.getLanguageTag();
		if (tag.isPresent()) {
		    System.out.println(tag.get());
		}

		System.out.println(literal.getLanguageTag().isPresent());
		System.out.println(literalDouble.getLanguageTag().isPresent());
	}

	@Test
	public void triple() throws Exception {
		BlankNodeOrIRI subject = factory.createBlankNode();
		IRI predicate = factory.createIRI("http://example.com/says");
		RDFTerm object = factory.createLiteral("Hello");
		triple = factory.createTriple(subject, predicate, object);

		BlankNodeOrIRI subj = triple.getSubject();
		System.out.println(subj.ntriplesString());

		IRI pred = triple.getPredicate();
		System.out.println(pred.getIRIString());

		RDFTerm obj = triple.getObject();
		System.out.println(obj.ntriplesString());

		if (subj instanceof IRI) {
		    String s = ((IRI) subj).getIRIString();
		    System.out.println(s);
		}
		// ..
		if (obj instanceof Literal) {
		    IRI type = ((Literal) obj).getDatatype();
		    System.out.println(type);
		}

		System.out.println(triple.equals(factory.createTriple(subj, pred, obj)));
	}


	@Test
	public void graph() throws Exception {


		Graph graph = factory.createGraph();

		graph.add(triple);

		IRI bob = factory.createIRI("http://example.com/bob");
		Literal bobName = factory.createLiteral("Bob");
		graph.add(bob, nameIri, bobName);


		System.out.println(graph.contains(triple));


		System.out.println(graph.contains(null, nameIri, bobName));

		System.out.println(graph.size());

		for (Triple t : graph.iterate()) {
			System.out.println(t.getObject());
		}


		for (Triple t : graph.iterate(null, null, bobName)) {
			System.out.println(t.getPredicate());
		}

		Stream<RDFTerm> subjects = graph.getTriples().map(t -> t.getObject());
		String s = subjects.map(RDFTerm::ntriplesString).collect(Collectors.joining(" "));
		System.out.println(s);

		Stream<? extends Triple> namedB = graph.getTriples(null, nameIri,null).
				filter(t -> t.getObject().ntriplesString().contains("B"));
		System.out.println(namedB.map(t -> t.getSubject()).findAny().get());

		graph.remove(triple);
		System.out.println(graph.contains(triple));

		graph.remove(null, nameIri, null);

		graph.clear();
		System.out.println(graph.contains(null, null, null));


	}


    public static String tripleAsString(Triple t) {
        return t.getSubject().ntriplesString() + " "
                + t.getPredicate().ntriplesString() + " " +
                t.getObject().ntriplesString() + " .";
    }

	public static void writeGraph(Graph graph, Path graphFile) throws Exception {
        Stream<CharSequence> stream = graph.getTriples().map(ExampleTest::tripleAsString);
        Files.write(graphFile, stream::iterator, Charset.forName("UTF-8"));
	}
}

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.example</groupId> <!--  Change to your groupId -->
	<artifactId>commons-rdf-examples</artifactId> <!-- Change to your artifactId -->
	<version>0.1-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

	<dependencies>
		<dependency>
			<groupId>org.apache.commons</groupId>
			<artifactId>commons-rdf-api</artifactId>
			<version>0.1-incubating-SNAPSHOT</version>
		</dependency>
		<dependency>
			<groupId>org.apache.commons</groupId>
			<artifactId>commons-rdf-simple</artifactId>
			<version>0.1.0-incubating-SNAPSHOT</version>
		</dependency>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>4.12</version>
			<scope>test</scope>
		</dependency>
	</dependencies>
	<repositories>
		<repository>
			<id>apache.snapshots</id>
			<name>Apache Snapshot Repository</name>
			<url>http://repository.apache.org/snapshots</url>
			<releases>
				<enabled>false</enabled>
			</releases>
		</repository>
	</repositories>

</project>