Prepare: made the project a java + scala project

prepare/build.gradle

@@ -1,18 +1,28 @@
 plugins {
 	id 'application'
+	id 'scala'
 }
 
+version '0.1'
+
 repositories {
 	mavenCentral()
 }
 
 dependencies {
+	implementation 'org.scala-lang:scala3-library_3:3.1.2'
 	implementation 'org.apache.jena:apache-jena-libs:4.4.0'
 	implementation 'org.apache.logging.log4j:log4j-core:2.17.2'
 	implementation 'org.slf4j:slf4j-simple:1.7.36'
 }
 
-version '0.1'
+sourceSets {
+	main {
+		java.srcDirs = ["src/main"]
+		scala.srcDirs = ["src/main"]
+		resources.srcDirs = ["src/resources"]
+	}
+}
 
 java {
 	sourceCompatibility = 11

prepare/src/main/Main.scala

@@ -0,0 +1,42 @@
+import org.apache.jena.query.QueryExecutionFactory
+import org.apache.jena.rdf.model.{InfModel, Model, ModelFactory}
+import org.apache.jena.reasoner.ReasonerRegistry
+
+import java.io.InputStream
+
+object Main extends App {
+
+	{
+		println("Loading knowledge graph...")
+		val kg: InfModel = ModelFactory.createInfModel(ReasonerRegistry.getTransitiveReasoner, ModelFactory.createDefaultModel)
+		val mondialDataset: InputStream = Option(ClassLoader.getSystemResourceAsStream("mondial_2022_04_04.n3"))
+			.getOrElse({
+				System.err.println("Impossible to open dataset")
+				System.exit(1)
+				null
+			})
+		kg.read(mondialDataset, null, "TTL");
+		printf("Loaded %s triples\n", kg.listStatements().toList.size)
+		val countries = getMondialNamedEntities(kg, "Country")
+		printf("There are %d countries in the dataset\n", countries.size)
+	}
+
+	def getMondialNamedEntities(kg: Model, prefixedType: String): List[NamedEntity] = {
+		var result: List[NamedEntity] = Nil
+		//noinspection HttpUrlsUsage
+		val MONDIAL_PREFIX = "http://www.semwebtech.org/mondial/10/meta#"
+		val fullType = MONDIAL_PREFIX + prefixedType;
+		val nameProperty = MONDIAL_PREFIX + "name"
+		val queryString = String.format("SELECT ?entity ?name WHERE { ?entity a <%s> ; <%s> ?name. }", fullType, nameProperty)
+		val resultSet = QueryExecutionFactory.create(queryString, kg).execSelect()
+		while (resultSet.hasNext) {
+			val solution = resultSet.next()
+			result = result :+ new NamedEntity(
+				solution.getLiteral("?name").getString,
+				solution.getResource("?entity")
+			)
+		}
+		result
+	}
+
+}

prepare/src/main/NamedEntity.scala

@@ -0,0 +1,5 @@
+import org.apache.jena.rdf.model.Resource
+
+class NamedEntity(val Name: String, val entity: Resource) {
+
+}

prepare/src/main/java/Main.java

@@ -1,60 +0,0 @@
-import org.apache.jena.query.QueryExecution;
-import org.apache.jena.query.QueryExecutionFactory;
-import org.apache.jena.query.QuerySolution;
-import org.apache.jena.query.ResultSet;
-import org.apache.jena.rdf.model.InfModel;
-import org.apache.jena.rdf.model.Model;
-import org.apache.jena.rdf.model.ModelFactory;
-import org.apache.jena.rdf.model.Resource;
-import org.apache.jena.reasoner.ReasonerRegistry;
-
-import java.io.InputStream;
-import java.util.HashMap;
-import java.util.Map;
-
-public final class Main
-{
-	public static void main(String[] args)
-	{
-		System.out.println("Loading knowledge graph...");
-		InfModel kg = ModelFactory.createInfModel(ReasonerRegistry.getTransitiveReasoner(), ModelFactory.createDefaultModel());
-		final InputStream mondialDataset = ClassLoader.getSystemResourceAsStream("mondial_2022_04_04.n3");
-		if (mondialDataset == null)
-		{
-			System.err.println("Impossible to open mondial dataset");
-			System.exit(1);
-		}
-		kg.read(mondialDataset, null, "TTL");
-		System.out.printf("Loaded %s triples\n", kg.listStatements().toList().size());
-
-		{
-			Map<String, Resource> countries = mondialGetEntitiesWithName(kg, "Country");
-			System.out.printf("There are %d countries in the dataset\n", countries.size());
-		}
-
-	}
-
-	private static Map<String, Resource> mondialGetEntitiesWithName(Model kg, String prefixedType)
-	{
-		Map<String, Resource> result = new HashMap<>();
-
-		String queryString = String.format("PREFIX m: <http://www.semwebtech.org/mondial/10/meta#> SELECT ?entity ?name WHERE { ?entity a m:%s ; m:name ?name. }", prefixedType);
-		try (QueryExecution execution = QueryExecutionFactory.create(queryString, kg))
-		{
-			final ResultSet resultSet = execution.execSelect();
-			while (resultSet.hasNext())
-			{
-				QuerySolution solution = resultSet.next();
-				Resource entity = solution.getResource("?entity");
-				String name = solution.getLiteral("?name").getString();
-				if (result.containsKey(name))
-				{
-					System.err.printf("Error: multiple entities with the name %s\n", name);
-					System.exit(1);
-				}
-				result.put(name, entity);
-			}
-		}
-		return result;
-	}
-}