Ordering schema test files lexikographically

ws/Unitmarking/src/main/java/de/hdm_stuttgart/mi/unitmarking/xsd/InstanceSetEvaluation.java

@@ -2,6 +2,7 @@ package de.hdm_stuttgart.mi.unitmarking.xsd;
 
 import java.io.File;
 import java.io.IOException;
+import java.util.Arrays;
 import java.util.List;
 import java.util.Vector;
 
@@ -56,14 +57,19 @@ public class InstanceSetEvaluation {
 	/**
 	 * 
 	 * @param xmlTestFileDir Directory containing XML instances to be processed.
+	 * @param xsdSchemaFilename Schema defining validation rules.
 	 */
 	public InstanceSetEvaluation(final String xmlTestFileDir, final String xsdSchemaFilename) {
 		this.xmlTestFileDir = xmlTestFileDir;
 
 		final File rootDirectory = new File(xmlTestFileDir);
 
-		for (final File f: rootDirectory.listFiles(
-				path -> path.getPath().endsWith(".xml"))) {
+		final File[] xmlFiles = rootDirectory.listFiles(
+            path -> path.getPath().endsWith(".xml"));
+		
+		Arrays.sort(xmlFiles);
+		
+		for (final File f: xmlFiles) {
 			readTestHeader(f, xsdSchemaFilename);
 		}