do not print null when no graph provided

buildNumber.properties

@@ -1,3 +1,3 @@
 #maven.buildNumber.plugin properties file
-#Fri Aug 17 13:40:48 CEST 2018
-buildNumber0=43
+#Mon Aug 27 13:58:09 CEST 2018
+buildNumber0=45

src/main/java/be/ugent/rml/Utils.java

@@ -3,7 +3,6 @@
 import be.ugent.rml.records.Record;
 import be.ugent.rml.store.Quad;
 import be.ugent.rml.store.QuadStore;
-import be.ugent.rml.store.TriplesQuads;
 import be.ugent.rml.store.RDF4JStore;
 import be.ugent.rml.term.Literal;
 import be.ugent.rml.term.NamedNode;
@@ -333,20 +332,6 @@ public static QuadStore readTurtle(File mappingFile) {
         return Utils.readTurtle(mappingFile, RDFFormat.TURTLE);
     }
 
-    public static boolean isBlankNode(String value) {
-        return value.startsWith("_:");
-    }
-
-    public static String toNTriples(List<Quad> quads) {
-        StringBuilder output = new StringBuilder();
-
-        for (Quad q : quads) {
-            output.append(Utils.getNTripleOfQuad(q) + "\n");
-        }
-
-        return output.toString();
-    }
-
     public static String toNQuads(List<Quad> quads) {
         StringBuilder output = new StringBuilder();
 
@@ -357,39 +342,22 @@ public static String toNQuads(List<Quad> quads) {
         return output.toString();
     }
 
-    public static void toNTriples(List<Quad> quads, Writer out) throws IOException {
-        for (Quad q : quads) {
-            out.write(Utils.getNTripleOfQuad(q) + "\n");
-        }
-    }
-
     public static void toNQuads(List<Quad> quads, Writer out) throws IOException {
         for (Quad q : quads) {
             out.write(Utils.getNQuadOfQuad(q) + "\n");
         }
     }
 
-    public static TriplesQuads getTriplesAndQuads(List<Quad> all) {
-        List<Quad> triples = new ArrayList<>();
-        List<Quad> quads = new ArrayList<>();
+    private static String getNQuadOfQuad(Quad q) {
+        String str = q.getSubject() + " " + q.getPredicate() + " " + q.getObject();
 
-        for (Quad q: all) {
-            if (q.getGraph() == null || q.getGraph().equals("")) {
-                triples.add(q);
-            } else {
-                quads.add(q);
-            }
+        if (q.getGraph() != null) {
+            str += " " + q.getGraph();
         }
 
-        return new TriplesQuads(triples, quads);
-    }
+        str += ".";
 
-    private static String getNTripleOfQuad(Quad q) {
-        return q.getSubject() + " " + q.getPredicate() + " " + q.getObject() + ".";
-    }
-
-    private static String getNQuadOfQuad(Quad q) {
-        return q.getSubject() + " " + q.getPredicate() + " " + q.getObject() + " " + q.getGraph() + ".";
+        return str;
     }
 
     public static String encodeURI(String url) {
@@ -448,8 +416,7 @@ public static int selectedColumnHash(String query) {
         throw new Error("Invalid query: " + query);
     }
 
-    public static String readFile(String path, Charset encoding) throws IOException
-    {
+    public static String readFile(String path, Charset encoding) throws IOException {
         if (encoding == null) {
             encoding = StandardCharsets.UTF_8;
         }

src/main/java/be/ugent/rml/cli/Main.java

@@ -6,7 +6,6 @@
 import be.ugent.rml.records.RecordsFactory;
 import be.ugent.rml.store.Quad;
 import be.ugent.rml.store.QuadStore;
-import be.ugent.rml.store.TriplesQuads;
 import be.ugent.rml.term.NamedNode;
 import be.ugent.rml.term.Term;
 import ch.qos.logback.classic.Level;
@@ -130,9 +129,11 @@ public static void main(String [] args) {
 
 
                 String outputFile = getPriorityOptionValue(outputfileOption, lineArgs, configFile);
-                if (!result.getQuads(null, null, null).isEmpty()) {
+                List<Quad> quads = result.getQuads(null, null, null);
+
+                if (!quads.isEmpty()) {
                     //write quads
-                    writeOutput("quad", result.getQuads(null, null, null, null), outputFile);
+                    writeOutput(quads, outputFile);
                 }
             }
         } catch( ParseException exp ) {
@@ -170,17 +171,17 @@ private static void setLoggerLevel(Level level) {
         ((ch.qos.logback.classic.Logger) root).setLevel(level);
     }
 
-    private static void writeOutput(String what, List<Quad> output, String outputFile) {
+    private static void writeOutput(List<Quad> output, String outputFile) {
         if (output.size() > 1) {
-            logger.info(output.size() + " " + what + "s were generated");
+            logger.info(output.size() + " quads were generated");
         } else {
-            logger.info(output.size() + " " + what + " was generated");
+            logger.info(output.size() + " quad was generated");
         }
 
         //if output file provided, write to triples output file
         if (outputFile != null) {
             File targetFile = new File(outputFile);
-            logger.info("Writing " + what + " to " + targetFile.getPath() + "...");
+            logger.info("Writing quads to " + targetFile.getPath() + "...");
 
             if (!targetFile.isAbsolute()) {
                 targetFile = new File(System.getProperty("user.dir") + "/" + outputFile);
@@ -189,23 +190,15 @@ private static void writeOutput(String what, List<Quad> output, String outputFil
             try {
                 BufferedWriter out = new BufferedWriter(new FileWriter(outputFile));
 
-                if (what.equals("triple")) {
-                    Utils.toNTriples(output, out);
-                } else {
-                    Utils.toNQuads(output, out);
-                }
+                Utils.toNQuads(output, out);
 
                 out.close();
                 logger.info("Writing to " + targetFile.getPath() + " is done.");
             } catch(IOException e) {
                 System.err.println( "Writing output to file failed. Reason: " + e.getMessage() );
             }
         } else {
-            if (what.equals("triple")) {
-                System.out.println(Utils.toNTriples(output));
-            } else {
-                System.out.println(Utils.toNQuads(output));
-            }
+            System.out.println(Utils.toNQuads(output));
         }
     }
 }