Fix the bug of NullPointerException.

src/main/java/edu/lu/uni/serval/FixPatternMiner/AkkaMiner.java

@@ -30,12 +30,13 @@ public class AkkaMiner {
 		
 		ActorSystem system = null;
 		ActorRef parsingActor = null;
-		final int numberOfWorkers = 100;
+		final int numberOfWorkers = 200;
+		final WorkMessage msg = new WorkMessage(0, msgFiles);
 		try {
 			log.info("Akka beings...");
 			system = ActorSystem.create("Mining-FixPattern-System");
 			parsingActor = system.actorOf(MineFixPatternActor.props(numberOfWorkers, editScriptsFilePath, patchesSourceCodeFilePath), "mine-fix-pattern-actor");
-			parsingActor.tell(msgFiles, ActorRef.noSender());
+			parsingActor.tell(msg, ActorRef.noSender());
 		} catch (Exception e) {
 			system.shutdown();
 			e.printStackTrace();

src/main/java/edu/lu/uni/serval/FixPatternMiner/MineFixPatternActor.java

@@ -43,8 +43,8 @@ public class MineFixPatternActor extends UntypedActor {
 	@SuppressWarnings("deprecation")
 	@Override
 	public void onReceive(Object message) throws Exception {
-		if (message instanceof List<?>) {
-			List<?> files = (List<?>) message;
+		if (message instanceof WorkMessage) {
+			List<MessageFile> files = ((WorkMessage) message).getMsgFiles();
 			int size = files.size();
 			int average = size / numberOfWorkers;
 			
@@ -55,9 +55,10 @@ public class MineFixPatternActor extends UntypedActor {
 					toIndex = size;
 				}
 				
-				List<Object> filesOfWorkers = new ArrayList<>();
+				List<MessageFile> filesOfWorkers = new ArrayList<>();
 				filesOfWorkers.addAll(files.subList(fromIndex, toIndex));
-				mineRouter.tell(filesOfWorkers, getSelf());
+				final WorkMessage workMsg = new WorkMessage(i + 1, filesOfWorkers);
+				mineRouter.tell(workMsg, getSelf());
 				logger.info("Assign a task to worker #" + (i + 1) + "...");
 			}
 		} else if ("STOP".equals(message.toString())) {

src/main/java/edu/lu/uni/serval/FixPatternMiner/MineFixPatternWorker.java

@@ -33,17 +33,17 @@ public class MineFixPatternWorker extends UntypedActor {
 
 	@Override
 	public void onReceive(Object message) throws Exception {
-		if (message instanceof List<?>) {
-			List<?> files = (List<?>) message;
+		if (message instanceof WorkMessage) {
+			WorkMessage msg = (WorkMessage) message;
+			List<MessageFile> files = msg.getMsgFiles();
 			StringBuilder editScripts = new StringBuilder();
 			StringBuilder patchesSourceCode = new StringBuilder();
-			for (Object obj : files) {
-				MessageFile msgFile = (MessageFile) obj;
+			for (MessageFile msgFile : files) {
 				File revFile = msgFile.getRevFile();
 				File prevFile = msgFile.getPrevFile();
 				File diffentryFile = msgFile.getDiffEntryFile();
 				if (!prevFile.exists()) {
-					System.out.println(prevFile.getPath());
+					System.out.println("Previous File:" + prevFile.getPath());
 					continue;
 				}
 				Miner miner = new Miner();
@@ -52,15 +52,13 @@ public class MineFixPatternWorker extends UntypedActor {
 					editScripts.append(miner.getAstEditScripts());
 					patchesSourceCode.append(miner.getPatchesSourceCode());
 				} catch (Exception e) {
-					System.out.println(revFile.getPath());
+					System.out.println("Revised File:" + revFile.getPath());
 					e.printStackTrace();
 				}
 			}
 			
-			List<File> subFiles1 = FileHelper.getAllFilesInCurrentDiectory(editScriptsFilePath, ".list");
-			List<File> subFiles2 = FileHelper.getAllFilesInCurrentDiectory(patchesSourceCodeFilePath, ".list");
-			FileHelper.outputToFile(editScriptsFilePath + "edistScripts" + subFiles1.size() + ".list", editScripts, false);
-			FileHelper.outputToFile(patchesSourceCodeFilePath + "patches" + subFiles2.size() + ".list", patchesSourceCode, false);
+			FileHelper.outputToFile(editScriptsFilePath + "edistScripts" + msg.getId() + ".list", editScripts, false);
+			FileHelper.outputToFile(patchesSourceCodeFilePath + "patches" + msg.getId() + ".list", patchesSourceCode, false);
 			
 			this.getSender().tell("STOP", getSelf());
 		} else {

src/main/java/edu/lu/uni/serval/FixPatternMiner/WorkMessage.java

@@ -0,0 +1,24 @@
+package edu.lu.uni.serval.FixPatternMiner;
+
+import java.util.List;
+
+public class WorkMessage {
+
+	private int id;
+	private List<MessageFile> msgFiles;
+	
+	public WorkMessage(int id, List<MessageFile> msgFiles) {
+		super();
+		this.id = id;
+		this.msgFiles = msgFiles;
+	}
+
+	public int getId() {
+		return id;
+	}
+
+	public List<MessageFile> getMsgFiles() {
+		return msgFiles;
+	}
+	
+}