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  • Parallel processing via multithreading in Java

    - by Robz
    There are certain algorithms whose running time can decrease significantly when one divides up a task and gets each part done in parallel. One of these algorithms is merge sort, where a list is divided into infinitesimally smaller parts and then recombined in a sorted order. I decided to do an experiment to test whether or not I could I increase the speed of this sort by using multiple threads. I am running the following functions in Java on a Quad-Core Dell with Windows Vista. One function (the control case) is simply recursive: // x is an array of N elements in random order public int[] mergeSort(int[] x) { if (x.length == 1) return x; // Dividing the array in half int[] a = new int[x.length/2]; int[] b = new int[x.length/2+((x.length%2 == 1)?1:0)]; for(int i = 0; i < x.length/2; i++) a[i] = x[i]; for(int i = 0; i < x.length/2+((x.length%2 == 1)?1:0); i++) b[i] = x[i+x.length/2]; // Sending them off to continue being divided mergeSort(a); mergeSort(b); // Recombining the two arrays int ia = 0, ib = 0, i = 0; while(ia != a.length || ib != b.length) { if (ia == a.length) { x[i] = b[ib]; ib++; } else if (ib == b.length) { x[i] = a[ia]; ia++; } else if (a[ia] < b[ib]) { x[i] = a[ia]; ia++; } else { x[i] = b[ib]; ib++; } i++; } return x; } The other is in the 'run' function of a class that extends thread, and recursively creates two new threads each time it is called: public class Merger extends Thread { int[] x; boolean finished; public Merger(int[] x) { this.x = x; } public void run() { if (x.length == 1) { finished = true; return; } // Divide the array in half int[] a = new int[x.length/2]; int[] b = new int[x.length/2+((x.length%2 == 1)?1:0)]; for(int i = 0; i < x.length/2; i++) a[i] = x[i]; for(int i = 0; i < x.length/2+((x.length%2 == 1)?1:0); i++) b[i] = x[i+x.length/2]; // Begin two threads to continue to divide the array Merger ma = new Merger(a); ma.run(); Merger mb = new Merger(b); mb.run(); // Wait for the two other threads to finish while(!ma.finished || !mb.finished) ; // Recombine the two arrays int ia = 0, ib = 0, i = 0; while(ia != a.length || ib != b.length) { if (ia == a.length) { x[i] = b[ib]; ib++; } else if (ib == b.length) { x[i] = a[ia]; ia++; } else if (a[ia] < b[ib]) { x[i] = a[ia]; ia++; } else { x[i] = b[ib]; ib++; } i++; } finished = true; } } It turns out that function that does not use multithreading actually runs faster. Why? Does the operating system and the java virtual machine not "communicate" effectively enough to place the different threads on different cores? Or am I missing something obvious?

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  • Java List to Excel Columns

    - by Nitin
    Correct me where I'm going wrong. I'm have written a program in Java which will get list of files from two different directories and make two (Java list) with the file names. I want to transfer the both the list (downloaded files list and Uploaded files list) to an excel. What the result i'm getting is those list are transferred row wise. I want them in column wise. Given below is the code: public class F { static List<String> downloadList = new ArrayList<>(); static List<String> dispatchList = new ArrayList<>(); public static class FileVisitor extends SimpleFileVisitor<Path> { @Override public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException { String name = file.toRealPath().getFileName().toString(); if (name.endsWith(".pdf") || name.endsWith(".zip")) { downloadList.add(name); } if (name.endsWith(".xml")) { dispatchList.add(name); } return FileVisitResult.CONTINUE; } } public static void main(String[] args) throws IOException { try { Path downloadPath = Paths.get("E:\\report\\02_Download\\10252013"); Path dispatchPath = Paths.get("E:\\report\\01_Dispatch\\10252013"); FileVisitor visitor = new FileVisitor(); Files.walkFileTree(downloadPath, visitor); Files.walkFileTree(downloadPath, EnumSet.of(FileVisitOption.FOLLOW_LINKS), 1, visitor); Files.walkFileTree(dispatchPath, visitor); Files.walkFileTree(dispatchPath, EnumSet.of(FileVisitOption.FOLLOW_LINKS), 1, visitor); System.out.println("Download File List" + downloadList); System.out.println("Dispatch File List" + dispatchList); F f = new F(); f.UpDown(downloadList, dispatchList); } catch (Exception ex) { Logger.getLogger(F.class.getName()).log(Level.SEVERE, null, ex); } } int rownum = 0; int colnum = 0; HSSFSheet firstSheet; Collection<File> files; HSSFWorkbook workbook; File exactFile; { workbook = new HSSFWorkbook(); firstSheet = workbook.createSheet("10252013"); Row headerRow = firstSheet.createRow(rownum); headerRow.setHeightInPoints(40); } public void UpDown(List<String> download, List<String> upload) throws Exception { List<String> headerRow = new ArrayList<>(); headerRow.add("Downloaded"); headerRow.add("Uploaded"); List<List> recordToAdd = new ArrayList<>(); recordToAdd.add(headerRow); recordToAdd.add(download); recordToAdd.add(upload); F f = new F(); f.CreateExcelFile(recordToAdd); f.createExcelFile(); } void createExcelFile() { FileOutputStream fos = null; try { fos = new FileOutputStream(new File("E:\\report\\Download&Upload.xls")); HSSFCellStyle hsfstyle = workbook.createCellStyle(); hsfstyle.setBorderBottom((short) 1); hsfstyle.setFillBackgroundColor((short) 245); workbook.write(fos); } catch (Exception e) { } } public void CreateExcelFile(List<List> l1) throws Exception { try { for (int j = 0; j < l1.size(); j++) { Row row = firstSheet.createRow(rownum); List<String> l2 = l1.get(j); for (int k = 0; k < l2.size(); k++) { Cell cell = row.createCell(k); cell.setCellValue(l2.get(k)); } rownum++; } } catch (Exception e) { } finally { } } } (The purpose is to verify the files Downloaded and Uploaded for the given date) Thanks.

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  • Java client listening to WebSphere MQ Server?

    - by user595234
    I need to write a Java client listening to WebSphere MQ Server. Message is put into a queue in the server. I developed this code, but am not sure it is correct or not. If correct, then how can I test it? This is a standalone Java project, no application server support. Which jars I should put into classpath? I have the MQ settings, where I should put into my codes? Standard JMS can skip these settings? confusing .... import javax.jms.Destination; import javax.jms.Message; import javax.jms.MessageConsumer; import javax.jms.MessageListener; import javax.jms.Queue; import javax.jms.QueueConnection; import javax.jms.QueueConnectionFactory; import javax.jms.QueueReceiver; import javax.jms.QueueSession; import javax.jms.Session; import javax.naming.Context; import javax.naming.InitialContext; import javax.naming.NamingException; public class Main { Context jndiContext = null; QueueConnectionFactory queueConnectionFactory = null; QueueConnection queueConnection = null; QueueSession queueSession = null; Queue controlQueue = null; QueueReceiver queueReceiver = null; private String queueSubject = ""; private void start() { try { queueConnection.start(); queueSession = queueConnection.createQueueSession(false, Session.AUTO_ACKNOWLEDGE); Destination destination = queueSession.createQueue(queueSubject); MessageConsumer consumer = queueSession.createConsumer(destination); consumer.setMessageListener(new MyListener()); } catch (Exception e) { e.printStackTrace(); } } private void close() { try { queueSession.close(); queueConnection.close(); } catch (Exception e) { e.printStackTrace(); } } private void init() { try { jndiContext = new InitialContext(); queueConnectionFactory = (QueueConnectionFactory) this.jndiLookup("QueueConnectionFactory"); queueConnection = queueConnectionFactory.createQueueConnection(); queueConnection.start(); } catch (Exception e) { System.err.println("Could not create JNDI API " + "context: " + e.toString()); System.exit(1); } } private class MyListener implements MessageListener { @Override public void onMessage(Message message) { System.out.println("get message:" + message); } } private Object jndiLookup(String name) throws NamingException { Object obj = null; if (jndiContext == null) { try { jndiContext = new InitialContext(); } catch (NamingException e) { System.err.println("Could not create JNDI API " + "context: " + e.toString()); throw e; } } try { obj = jndiContext.lookup(name); } catch (NamingException e) { System.err.println("JNDI API lookup failed: " + e.toString()); throw e; } return obj; } public Main() { } public static void main(String[] args) { new Main(); } } MQ Queue setting <queue-manager> <name>AAA</name> <port>1423</port> <hostname>ddd</hostname> <clientChannel>EEE.CLIENTS.00</clientChannel> <securityClass>PKIJCExit</securityClass> <transportType>1</transportType> <targetClientMatching>1</targetClientMatching> </queue-manager> <queues> <queue-details id="queue-1"> <name>GGGG.NY.00</name> <transacted>false</transacted> <acknowledgeMode>1</acknowledgeMode> <targetClient>1</targetClient> </queue-details> </queues>

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  • sort surname in alphabet from file to file JAVA

    - by user577939
    hello all. I need some help. I have wrote this code and dont now how to sort surnames in alphabet from my file to other file. import java.io.; import java.util.; class Asmuo { String pavarde; String vardas; long buvLaikas; int atv1; int atv2; int atv3; } class Irasas { Asmuo duom; Irasas kitas; } class Sarasas { private Irasas p; Sarasas() { p = null; } Irasas itrauktiElementa(String pv, String v, long laikas, int d0, int d1, int d2) { String pvrd, vrd; int data0; int data1; int data2; long lks; lks = laikas; pvrd = pv; vrd = v; data0 = d0; data1 = d1; data2 = d2; Irasas r = new Irasas(); r.duom = new Asmuo(); uzpildymasDuomenimis(r, pvrd, vrd, lks, d0, d1, d2); r.kitas = p; p = r; return r; } void uzpildymasDuomenimis(Irasas r, String pv, String v, long laik, int d0, int d1, int d2) { r.duom.pavarde = pv; r.duom.vardas = v; r.duom.atv1 = d0; r.duom.buvLaikas = laik; r.duom.atv2 = d1; r.duom.atv3 = d2; } void spausdinti() { Irasas d = p; int i = 0; try { FileWriter fstream = new FileWriter("rez.txt"); BufferedWriter rez = new BufferedWriter(fstream); while (d != null) { System.out.println(d.duom.pavarde + " " + d.duom.vardas + " " + d.duom.buvLaikas + " " + d.duom.atv1 + " " + d.duom.atv2 + " " + d.duom.atv3); rez.write(d.duom.pavarde + " " + d.duom.vardas + " " + d.duom.buvLaikas + " " + d.duom.atv1 + " " + d.duom.atv2 + " " + d.duom.atv3 + "\n"); d = d.kitas; i++; } rez.close(); } catch (Exception e) { System.err.println("Error: " + e.getMessage()); } } } public class Gyventojai { public static void main(String args[]) { Sarasas sar = new Sarasas(); Calendar atv = Calendar.getInstance(); Calendar isv = Calendar.getInstance(); try { FileInputStream fstream = new FileInputStream("duom.txt"); DataInputStream in = new DataInputStream(fstream); BufferedReader br = new BufferedReader(new InputStreamReader(in)); String eil; while ((eil = br.readLine()) != null) { String[] cells = eil.split(" "); String pvrd = cells[0]; String vrd = cells[1]; atv.set(Integer.parseInt(cells[2]), Integer.parseInt(cells[3]), Integer.parseInt(cells[4])); isv.set(Integer.parseInt(cells[5]), Integer.parseInt(cells[6]), Integer.parseInt(cells[7])); long laik = (isv.getTimeInMillis() - atv.getTimeInMillis()) / (24 * 60 * 60 * 1000); int d0 = Integer.parseInt(cells[2]); int d1 = Integer.parseInt(cells[3]); int d2 = Integer.parseInt(cells[4]); sar.itrauktiElementa(pvrd, vrd, laik, d0, d1, d2); } in.close(); } catch (Exception e) { System.err.println("Error: " + e.getMessage()); } sar.spausdinti(); } }

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  • Problem with sending out variable to serial port using api JAVA

    - by sjaakensjon
    We are developing a java program for school. But we are experiencing problems with sending out a variable created by 3 sliders. The idea is that we have 3 sliders. One slider for every color. Red green and blue. The variable has to have a value between 0 and 255. Everytime the value of the slider changes is has to send a variable for the channel, that value is 1, 2 ,3. And after that it has to send the value of the slider through the serial port. Could you please help us out by creating an example program? Below is our code so far. Thanks in advance. Sjaak package main; import javax.swing.*; import javax.swing.event.*; import java.awt.*; import app.Com; import app.Parameters; public class menu{ JSlider sliderblauw; JLabel hoeveelblauw; JLabel blauw; JLabel rood; JSlider sliderrood; JLabel hoeveelrood; JLabel groen; JLabel hoeveelgroen; JSlider slidergroen; public menu(){ Frame venster = new JFrame("Color control"); JPanel blauwinstel = new JPanel(); ((JFrame) venster).setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); venster.setSize(500, 500); venster.setVisible(true); sliderblauw = new JSlider(JSlider.VERTICAL, 0, 255, 0); sliderblauw.addChangeListener(new veranderingblauw()); hoeveelblauw = new JLabel ("0"); blauwinstel.add(sliderblauw); blauwinstel.add(hoeveelblauw); venster.add(blauwinstel, BorderLayout.WEST); sliderblauw.setMajorTickSpacing(10); sliderblauw.setPaintTicks(true); JPanel roodinstel = new JPanel(); sliderrood = new JSlider(JSlider.VERTICAL, 0, 255, 0); sliderrood.addChangeListener(new veranderingrood()); hoeveelrood = new JLabel ("0"); roodinstel.add(sliderrood); roodinstel.add(hoeveelrood); venster.add(roodinstel, BorderLayout.EAST); sliderrood.setMajorTickSpacing(10); sliderrood.setPaintTicks(true); JPanel groeninstel = new JPanel(); slidergroen = new JSlider(JSlider.VERTICAL, 0, 255, 0); slidergroen.addChangeListener(new veranderinggroen()); hoeveelgroen = new JLabel ("0"); groeninstel.add(slidergroen); groeninstel.add(hoeveelgroen); venster.add(groeninstel, BorderLayout.CENTER); slidergroen.setMajorTickSpacing(10); slidergroen.setPaintTicks(true); } public class veranderingblauw implements ChangeListener{ public void stateChanged(ChangeEvent ce){ int value = sliderblauw.getValue(); String waarde_blauw = Integer.toString(value); hoeveelblauw.setText(waarde_blauw); }} public class veranderingrood implements ChangeListener{ public void stateChanged(ChangeEvent ce){ int value = sliderrood.getValue(); String waarde_rood = Integer.toString(value); hoeveelrood.setText(waarde_rood); }} public class veranderinggroen implements ChangeListener{ public void stateChanged(ChangeEvent ce){ int value = slidergroen.getValue(); String waarde_groen = Integer.toString(value); hoeveelgroen.setText(waarde_groen); }} public static void main( String[] args) { new menu(); } }

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  • retrieving value from database in java

    - by Akcire Atienza
    I am making AGAIN another program that retrieves the inputted data/values of fields from the database I created. but this time, my inputted value will be coming from the JtextField I created. I wonder what's wrong in here bec when I'm running it the output is always null. in this program i will convert the inputted value of my JTextField into int. here it is: public class ButtonHandler implements ActionListener { public void actionPerformed(ActionEvent e) { if(e.getSource() == extendB) { ExtensionForm extend = new ExtensionForm(); extend.setVisible(true); } else if(e.getSource()== searchB) { //get text from the textField String guest = guestIDTF.getText(); //parse the string to integer for retrieving of data int id = Integer.parseInt(guest); GuestsInfo guestInfo = new GuestsInfo(id); Room roomInfo = new Room(id); String labels[] = {guestInfo.getFirstName()+" "+guestInfo.getLastName(),""+roomInfo.getRoomNo(),roomInfo.getRoomType(),guestInfo.getTime(),"11:00"}; for(int z = 0; z<labels.length; z++) { labelDisplay[z].setText(labels[z]); } in my second class it retrieves the inputted values of fields from the database I created here's the code: import java.sql.*; public class Room { private String roomType; private int guestID, roomNo; private Connection con; private PreparedStatement statement; public Room(){ try { Class.forName("com.mysql.jdbc.Driver"); con = DriverManager.getConnection( "jdbc:mysql://localhost:3306/3moronsdb","root",""); } catch (Exception e) { e.printStackTrace(); } } public Room(int guestsID) { this(); try{ statement = con.prepareStatement("SELECT * FROM guest WHERE guestID=?"); statement.setInt(1, guestID); ResultSet rs = statement.executeQuery(); while(rs.next()){ this.guestID = rs.getInt(1); this.roomType = rs.getString(2); this.roomNo = rs.getInt(3); } }catch(Exception e){ System.out.print(e); } } //Constructor for setting rate public Room(String roomType, int roomNo) { this(); try { statement = con.prepareStatement("Insert into room(roomType, roomNo) values(?,?)"); statement.setString(1, roomType); statement.setInt(2, roomNo); statement.executeUpdate(); } catch(Exception e) { e.printStackTrace(); return; } } //getting roomType public String getRoomType(){ return roomType; } //getting roomNo public int getRoomNo(){ return roomNo; } //getting guestID public int getGuestId(){ return guestID; } } i already insert some values in my 3moronsdb which are ( 1, Classic , 103). here's my TEST main class: public class TestMain { public static void main(String [] a){ GuestsInfo guest = new GuestsInfo(1); //note that this instantiation is the other class which i just ask the other day.. (http://stackoverflow.com/questions/12762835/retrieving-values-from-database-in-java) Room rum = new Room(1); System.out.print(rum.getRoomType()+" "+ guest.getFirstName()); } } when i'm running it it only gives me null output for the Room class but i am getting the output of the GuestsInfo class which is 'Ericka'. Can you help me guys? I know I ask this kind of problem yesterday but i really don't know what's wrong in here now..

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  • TCP client in C and server in Java

    - by faldren
    I would like to communicate with 2 applications : a client in C which send a message to the server in TCP and the server in Java which receive it and send an acknowledgement. Here is the client (the code is a thread) : static void *tcp_client(void *p_data) { if (p_data != NULL) { char const *message = p_data; int sockfd, n; struct sockaddr_in serv_addr; struct hostent *server; char buffer[256]; sockfd = socket(AF_INET, SOCK_STREAM, 0); if (sockfd < 0) { error("ERROR opening socket"); } server = gethostbyname(ALARM_PC_IP); if (server == NULL) { fprintf(stderr,"ERROR, no such host\n"); exit(0); } bzero((char *) &serv_addr, sizeof(serv_addr)); serv_addr.sin_family = AF_INET; bcopy((char *)server->h_addr, (char *)&serv_addr.sin_addr.s_addr, server->h_length); serv_addr.sin_port = htons(TCP_PORT); if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0) { error("ERROR connecting"); } n = write(sockfd,message,strlen(message)); if (n < 0) { error("ERROR writing to socket"); } bzero(buffer,256); n = read(sockfd,buffer,255); if (n < 0) { error("ERROR reading from socket"); } printf("Message from the server : %s\n",buffer); close(sockfd); } return 0; } And the java server : try { int port = 9015; ServerSocket server=new ServerSocket(port); System.out.println("Server binded at "+((server.getInetAddress()).getLocalHost()).getHostAddress()+":"+port); System.out.println("Run the Client"); while (true) { Socket socket=server.accept(); BufferedReader in= new BufferedReader(new InputStreamReader(socket.getInputStream())); System.out.println(in.readLine()); PrintStream out=new PrintStream(socket.getOutputStream()); out.print("Welcome by server\n"); out.flush(); out.close(); in.close(); System.out.println("finished"); } } catch(Exception err) { System.err.println("* err"+err); } With n = read(sockfd,buffer,255); the client is waiting a response and for the server, the message is never ended so it doesn't send a response with PrintStream. If I remove these lines : bzero(buffer,256); n = read(sockfd,buffer,255); if (n < 0) { error("ERROR reading from socket"); } printf("Message from the server : %s\n",buffer); The server knows that the message is finished but the client can't receive the response. How solve that ? Thank you

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  • Java File I/O problems

    - by dwwilson66
    This is my first time working with file i/o in java, and it's not working. The section of the program where I parse individual lines and output a semicolon delimited line works like a charm when I hardcode a file and display on screen. Whne I try to write to a file public static OutputStream... errors out as an illegal start to expression, and I've been unable to get the program to step through an entire directory of files instead of one at a time. Where I'm not clear: I'm note setting an output filename anywhere...whare am I supposed to do that? The path variable won't pass. What's the proper format for a path? Can anyone see what I need to debug here? import java.io.*; public class FileRead { public static void main(String args[]) { try { // Open the file(s) // single file works OK FileInputStream fstream = new FileInputStream("testfile.txt"); Path startingDir = R:\Data\cs\RoboHelp\CorrLib\Output\Production\WebHelp; PrintFiles pf = new PrintFiles(); Files.walkFileTree(startingDir, pf); // Get the object of DataInputStream DataInputStream in = new DataInputStream(fstream); BufferedReader br = new BufferedReader(new InputStreamReader(in)); String inputLine; String desc = ""; String docNo = ""; String replLtr = ""; String specCond = ""; String states = ""; String howGen = ""; String whenGen = ""; String owner = ""; String lastChange = ""; //Read File Line By Line while ((inputLine = br.readLine()) != null) { int testVal=0; int stringMax = inputLine.length(); // if(inputLine.startsWith("Description")) {desc = inputLine.substring(13,inputLine.length());} else if(inputLine.startsWith("Reference Number")) {docNo = inputLine.substring(20,inputLine.length());} else if(inputLine.startsWith("Replaces Letter")) {replLtr = inputLine.substring(17,inputLine.length());} else if(inputLine.startsWith("Special Conditions")) {specCond = inputLine.substring(21,inputLine.length());} else if(inputLine.startsWith("States Applicable")) {states = inputLine.substring(19,inputLine.length());} else if(inputLine.startsWith("How Generated")) {howGen = inputLine.substring(15,inputLine.length());} else if(inputLine.startsWith("When Generated")) {whenGen = inputLine.substring(16,inputLine.length());} else if(inputLine.startsWith("Owner")) {owner = inputLine.substring(7,inputLine.length());} else if(inputLine.startsWith("Last Change Date")) {lastChange = inputLine.substring(17,inputLine.length());} } //close while loop // Print the content on the console String outStr1 = (desc + ";" + docNo + ";" + replLtr + ";" + specCond + ";" + states); String outStr2 = (";" + howGen + ";" + whenGen + ";" + owner + ";" + lastChange); String outString = (outStr1 + outStr2); System.out.print(inputLine + "\n" + outString); String lineItem = (outStr1+outStr2); // try (OutputStream out = new BufferedOutputStream (logfile.newOutputStream(CREATE, APPEND))) { out.write(lineItem, 0, lineItem.length); } catch (IOException x) { System.err.println(x); } public static OutputStream newOutputStream() throws IOException { // append to an existing file, create file if it doesn't initially exist out = Files.newOutputStream(c:, CREATE, APPEND); } //Close the input stream in.close(); } catch (Exception e) { //Catch exception if any System.err.println("Error: " + e.getMessage()); } } }

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  • How to generalize a method call in Java (to avoid code duplication)

    - by dln385
    I have a process that needs to call a method and return its value. However, there are several different methods that this process may need to call, depending on the situation. If I could pass the method and its arguments to the process (like in Python), then this would be no problem. However, I don't know of any way to do this in Java. Here's a concrete example. (This example uses Apache ZooKeeper, but you don't need to know anything about ZooKeeper to understand the example.) The ZooKeeper object has several methods that will fail if the network goes down. In this case, I always want to retry the method. To make this easy, I made a "BetterZooKeeper" class that inherits the ZooKeeper class, and all of its methods automatically retry on failure. This is what the code looked like: public class BetterZooKeeper extends ZooKeeper { private void waitForReconnect() { // logic } @Override public Stat exists(String path, Watcher watcher) { while (true) { try { return super.exists(path, watcher); } catch (KeeperException e) { // We will retry. } waitForReconnect(); } } @Override public byte[] getData(String path, boolean watch, Stat stat) { while (true) { try { return super.getData(path, watch, stat); } catch (KeeperException e) { // We will retry. } waitForReconnect(); } } @Override public void delete(String path, int version) { while (true) { try { super.delete(path, version); return; } catch (KeeperException e) { // We will retry. } waitForReconnect(); } } } (In the actual program there is much more logic and many more methods that I took out of the example for simplicity.) We can see that I'm using the same retry logic, but the arguments, method call, and return type are all different for each of the methods. Here's what I did to eliminate the duplication of code: public class BetterZooKeeper extends ZooKeeper { private void waitForReconnect() { // logic } @Override public Stat exists(final String path, final Watcher watcher) { return new RetryableZooKeeperAction<Stat>() { @Override public Stat action() { return BetterZooKeeper.super.exists(path, watcher); } }.run(); } @Override public byte[] getData(final String path, final boolean watch, final Stat stat) { return new RetryableZooKeeperAction<byte[]>() { @Override public byte[] action() { return BetterZooKeeper.super.getData(path, watch, stat); } }.run(); } @Override public void delete(final String path, final int version) { new RetryableZooKeeperAction<Object>() { @Override public Object action() { BetterZooKeeper.super.delete(path, version); return null; } }.run(); return; } private abstract class RetryableZooKeeperAction<T> { public abstract T action(); public final T run() { while (true) { try { return action(); } catch (KeeperException e) { // We will retry. } waitForReconnect(); } } } } The RetryableZooKeeperAction is parameterized with the return type of the function. The run() method holds the retry logic, and the action() method is a placeholder for whichever ZooKeeper method needs to be run. Each of the public methods of BetterZooKeeper instantiates an anonymous inner class that is a subclass of the RetryableZooKeeperAction inner class, and it overrides the action() method. The local variables are (strangely enough) implicitly passed to the action() method, which is possible because they are final. In the end, this approach does work and it does eliminate the duplication of the retry logic. However, it has two major drawbacks: (1) it creates a new object every time a method is called, and (2) it's ugly and hardly readable. Also I had to workaround the 'delete' method which has a void return value. So, here is my question: is there a better way to do this in Java? This can't be a totally uncommon task, and other languages (like Python) make it easier by allowing methods to be passed. I suspect there might be a way to do this through reflection, but I haven't been able to wrap my head around it.

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  • Problems with instantiating in JAVA

    - by PUPIALEX
    When running, below programme cannot reach the end of the main function.. I am new to JAVA, and cannot find its defections.. I need your help. Thanks. import java.util.*; class Schedule { public String day; private int startTime, endTime; public Schedule(String input_day, int input_start, int input_end) { day = input_day; startTime = input_start; endTime = input_end; } /* clashWith: to check whether this schedule clash with a Schedule called otherSchedule * PRE-Condition : input must be of Schedule type * POST-Condition : return true if two Schedule clash, return false if not. */ public boolean clashWith(Schedule otherSchedule) { if(this.day != otherSchedule.day || this.endTime <= otherSchedule.startTime || this.startTime >= otherSchedule.endTime) return false; return true; } } class Module { String code; Schedule lecture, tutorial, lab; public Module(String input_code, Schedule input_lecture, Schedule input_tutorial, Schedule input_lab) { code = input_code; lecture = input_lecture; tutorial = input_tutorial; lab = input_lab; } /* count: to count number of classes(lecture, tutorial, and lab of only this Module) on day. * For example: when day = "Monday", lecture is on Monday, tutorial is on Monday * but lab is on Tuesday, then return 2. (lecture and tutorial are on Monday). * PRE-Condition : * POST-Condition : */ public int count(String day) { int num = 0; if(lecture.day == day) num++; if(tutorial.day == day) num++; if(lab.day == day) num++; return num; } /* clashWith: to check whether this module clash with a Module called otherModule * PRE-Condition : * POST-Condition : */ public boolean clashWith(Module otherModule) { if(lecture.clashWith(otherModule.lecture) || lecture.clashWith(otherModule.tutorial) || lecture.clashWith(otherModule.lab) ) return true; if(tutorial.clashWith(otherModule.lecture) || tutorial.clashWith(otherModule.tutorial) || tutorial.clashWith(otherModule.lab)) return true; if(lab.clashWith(otherModule.lecture) || lab.clashWith(otherModule.tutorial) || lab.clashWith(otherModule.lab)) return true; return false; } } class Timetable { Vector<Module> listOfModule; public Timetable() { } /* checkClash: to check whether otherModule clash with one of * the modules in our timetable list. * PRE-Condition : * POST-Condition : */ public boolean checkClash(Module otherModule) { for(Module c: listOfModule) if(c.clashWith(otherModule)) return true; return false; } /* add: to add a new module to the timetable list. * PRE-Condition : * POST-Condition : */ public void add(Module module) { listOfModule.add(module); } /* count: to count number of classes on day. * PRE-Condition : * POST-Condition : */ public int count(String day) { int count_day=0; for(Module c: listOfModule) count_day += c.count(day); return count_day; } } public class Main { public static void main(String[] args) { Scanner input = new Scanner(System.in); int num_operation; String code ; Timetable userTimetable = new Timetable(); num_operation = input.nextInt(); for(int i=0;i<num_operation;i++) { if(input.next() == "MODULE") { code = input.next(); String day; int start, end; Schedule getLecSche = new Schedule(input.next(),input.nextInt(),input.nextInt()); Schedule getTutSche = new Schedule(input.next(),input.nextInt(),input.nextInt()); Schedule getLabSche = new Schedule(input.next(),input.nextInt(),input.nextInt()); Module userModule = new Module(code, getLecSche, getTutSche, getLabSche); System.out.println("Reached line 162"); if(!userTimetable.checkClash(userModule)) { userTimetable.add(userModule); System.out.println("Added"); } else System.out.println("Clashed"); } else if(input.next() == "COUNT"){ code = input.next(); System.out.println(userTimetable.count(code)); } } } }

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  • Need help in creating test application in Java and passing parameters into a new designed Java API.

    - by Christophe
    Need help, Please!!! By following the protocol, the Request should be built in 5 byte length, including 1 byte for changing Braud rate (Speed), and send request to a RS-232 port. Protocol: Request for the command processing, with optional extra byte for changing Baud Rate: LGT : length message ( LGT = 5 ) TYPE : 0x06 TO(time out): 0x0000 CMD : (1 byte) 0x02 application update Baud Rate : (1 byte) 0xNN (optional parameter to change baud rate of the Mnt App) where NN can be: 0x00 = No Baud Rate Change (similar to 4-byte command above) 0x09 = Change to 9600 Baud for Application Update speed 0x0A = Change to 19200 Baud for Application Update speed 0x0E = Change to 115200 Baud for Application Update speed All other bytes are not accepted and will result in a status of 0x01. I'm trying to test if my code works or not by creating another class (TestApplication.java) and pass the "3 differenr Baut rate" to this CPXAppliaction. the 3 Baud Rate is supposed to input by reading a file.txt. Question: How do you think these code (first half)? please don't warry about the details about the "sending part". I mean, do I need setter/getter for the "speed" parameter pass? I created the demo test class DemoApp.java (input speed by reading a txt file, and pass into CPXAppliaction). how do you think about that code? Many thanks to you guys!! public class CPXApplication extends CPXCommand { private int speed; . public CPXApplication() { speed = 9600; } public CPXApplication(int speedinit) { speed = speedinit; // TODO: where to get the speed? } protected void buildRequest() throws ElitePortException { String trans = ""; // build the full-qualified message following the protocol trans = addToRequest(trans, (char) 0); trans = addToRequest(trans, (char) 5); trans = addToRequest(trans, (char) 6); trans = addToRequest(trans, (char) 0); trans = addToRequest(trans, (char) 0); trans = addToRequest(trans, (char) 2); switch (speed) { case 9600: trans = addToRequest(trans, (char) 0x09); break; case 19200: trans = addToRequest(trans, (char) 0x0A); break; case 115200: trans = addToRequest(trans, (char) 0x0E); break; default: // TODO: unexpected baud rate. throw(); break; } trans = EncryptBinary(trans); trans = "F0." + trans; wrapRequest(trans); } protected String addToRequest(String req, char c) { return req + c; } protected String addToRequest(String req, String s) { return req + s; } protected String addToRequest(String req) { return req; } public void analyzeResponse() { //.............. } } Here is the demo test code: class Run { public static void run() { CPXAppliaction input = new CpXApplication(); int lineno = 0; try { FileReader fr = new FileReader("baudRateSpeed.txt"); BufferedReader reader = new BufferedReader(fr); String line = reader.readLine(); Scanner scan = null; while (line != null) { scan = new Scanner(line); String speed; speed = scan.next(); if (lineno == 0) { input.speed = speed; lineno++; } else { input = cpxapplication(speed, input); } line = reader.readLine(); } reader.close(); } catch (FileNotFoundException e) { System.out.println("Could not find the file"); } catch (IOException e) { System.out.println("Had a problem reading from file"); } } } public class DemoApp{ public void main(String args[]) { run(); }

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  • javaws not found

    - by Hunt
    I have a server which has centos installed in it. Recently I have installed jdk 1.6 into it. When I try to run java command from shell it's working perfectly fine. Java is stored into /usr/java/jdk1.6.0_25 and path is set to /usr/bin/ when I type which java. When I tried running javaws (which comes with the jdk 1.6 only) it is showing me following error: Java Web Start splash screen process exiting ... Bad installation: JAVAWS_HOME not set: No such file or directory Executing env command prints following details: HOSTNAME=XX-XXX-XXX-XX TERM=xterm SHELL=/bin/bash HISTSIZE=1000 OLDPWD=/usr/java SSH_TTY=/dev/pts/1 USER=root LS_COLORS=no=00:fi=00:di=00;34:ln=00;36:pi=40;33:so=00;35:bd=40;33;01:cd=40;33;01:or=01;05;37;41:mi=01;05;37;41:ex=00;32:*.cmd=00;32:*.exe=00;32:*.com=00;32:*.btm=00;32:*.bat=00;32:*.sh=00;32:*.csh=00;32:*.tar=00;31:*.tgz=00;31:*.arj=00;31:*.taz=00;31:*.lzh=00;31:*.zip=00;31:*.z=00;31:*.Z=00;31:*.gz=00;31:*.bz2=00;31:*.bz=00;31:*.tz=00;31:*.rpm=00;31:*.cpio=00;31:*.jpg=00;35:*.gif=00;35:*.bmp=00;35:*.xbm=00;35:*.xpm=00;35:*.png=00;35:*.tif=00;35: JAVA_PATH=/usr/java/jre1.6.0_24/jre/bin MAIL=/var/spool/mail/root PATH=/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin:/usr/java/jre1.6.0_24/jre/bin INPUTRC=/etc/inputrc PWD=/usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin JAVA_HOME=/usr/java/jre1.6.0_24/jre/bin LANG=en_US.UTF-8 SSH_ASKPASS=/usr/libexec/openssh/gnome-ssh-askpass SHLVL=1 HOME=/root LOGNAME=root JAVAWS_HOME=/usr/java/jre1.6.0_24/bin SSH_CONNECTION=175.100.170.26 3387 64.150.190.94 22 LESSOPEN=|/usr/bin/lesspipe.sh %s G_BROKEN_FILENAMES=1 _=/bin/env

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  • Problem with tomcat and getLocalHost exception

    - by xain
    I'm running a Linux server named S1 in a "cloud" server, and when tomcat 6.0.24 starts, I get the exception: org.apache.catalina.connector.Connector pause SEVERE: Protocol handler pause failed java.net.UnknownHostException: S1: S1 at java.net.InetAddress.getLocalHost(InetAddress.java:1353) at org.apache.jk.common.ChannelSocket.unLockSocket(ChannelSocket.java:485) Which then leads to: ERROR ehcache.Cache - Unable to set localhost. This prevents creation of a GUID. Cause was: Sjira1: S1 java.net.UnknownHostException: S1: S1 at java.net.InetAddress.getLocalHost(InetAddress.java:1353) at net.sf.ehcache.Cache.<clinit>(Cache.java:143) My hosts file is: 127.0.0.1 localhost localhost.localdomain (valid-ip-address) S1 S1.(valid domain name) ping S1 and S1.(valid domain name) return valid ip address nslookup S1.(valid domain name) returns valid ip address nslookup S1 throws ** server can't find S1: NXDOMAIN Any ideas about how to fix this ? Thanks

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  • Problem with tomcat and getLocalHost exception

    - by xain
    I'm running a Linux server named S1 in a "cloud" server, and when tomcat 6.0.24 starts, I get the exception: org.apache.catalina.connector.Connector pause SEVERE: Protocol handler pause failed java.net.UnknownHostException: S1: S1 at java.net.InetAddress.getLocalHost(InetAddress.java:1353) at org.apache.jk.common.ChannelSocket.unLockSocket(ChannelSocket.java:485) Which then leads to: ERROR ehcache.Cache - Unable to set localhost. This prevents creation of a GUID. Cause was: Sjira1: S1 java.net.UnknownHostException: S1: S1 at java.net.InetAddress.getLocalHost(InetAddress.java:1353) at net.sf.ehcache.Cache.<clinit>(Cache.java:143) My hosts file is: 127.0.0.1 localhost localhost.localdomain (valid-ip-address) S1 S1.(valid domain name) ping S1 and S1.(valid domain name) return valid ip address nslookup S1.(valid domain name) returns valid ip address nslookup S1 throws ** server can't find S1: NXDOMAIN Any ideas about how to fix this ? Thanks

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  • Playing an Online mp3

    - by Mohsen
    I have a problem with playing online mp3s. I'm using latest version of javazoom's jlayer and basicplayer. Here is the exception: Caused by: javazoom.jlgui.basicplayer.BasicPlayerException: java.io.EOFException at javazoom.jlgui.basicplayer.BasicPlayer.initAudioInputStream(Unknown Source) at javazoom.jlgui.basicplayer.BasicPlayer.open(Unknown Source) ... 12 more Caused by: java.io.EOFException at java.io.DataInputStream.readInt(DataInputStream.java:375) at com.sun.media.sound.WaveFileReader.getFMT(WaveFileReader.java:244) at com.sun.media.sound.WaveFileReader.getAudioFileFormat(WaveFileReader.java:85) at javax.sound.sampled.AudioSystem.getAudioFileFormat(AudioSystem.java:985) at javazoom.jlgui.basicplayer.BasicPlayer.initAudioInputStream(Unknown Source) ... 15 more My java is 1.6.0_16. Certain files cannot be player through the Internet. I have a set of mp3s, playing one after the other. Randomly one mp3 doesn't work throwing above exception. Some mp3s can be played by calling again play() method if javazoom's basicplayer, but others can never be played online. I was able to find this post but I doubt if this really relates to my directx version or something. Mohsen

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  • deploying war on tomcat fails to start

    - by Asghar
    i have a java application which uses JAX_WS when i deployed on my tomcat5 server . it is deployed successfully. but it fails to start SEVERE: WSSERVLET11: failed to parse runtime descriptor: java.lang.IllegalArgumentException: prefix cannot be "null" when creating a QName java.lang.IllegalArgumentException: prefix cannot be "null" when creating a QName at javax.xml.namespace.QName.<init>(xml-commons-apis-1.3.02.jar.so) at gnu.xml.stream.XMLParser.getAttributeName(libgcj.so.7rh) at com.sun.xml.ws.util.xml.XMLStreamReaderFilter.getAttributeName(XMLStreamReaderFilter.java:228) at com.sun.xml.ws.streaming.XMLStreamReaderUtil$AttributesImpl.<init>(XMLStreamReaderUtil.java:355) at com.sun.xml.ws.streaming.XMLStreamReaderUtil.getAttributes(XMLStreamReaderUtil.java:198) at com.sun.xml.ws.transport.http.DeploymentDescriptorParser.parseAdapters(DeploymentDescriptorParser.java:204) at com.sun.xml.ws.transport.http.DeploymentDescriptorParser.parse(DeploymentDescriptorParser.java:147) at com.sun.xml.ws.transport.http.servlet.WSServletContextListener.contextInitialized(WSServletContextListener.java:124) at org.apache.catalina.core.StandardContext.listenerStart(catalina-5.5.23.jar.so) at org.apache.catalina.core.StandardContext.start(catalina-5.5.23.jar.so) at org.apache.catalina.manager.ManagerServlet.start(catalina-manager-5.5.23.jar.so) at org.apache.catalina.manager.HTMLManagerServlet.start(catalina-manager-5.5.23.jar.so) at org.apache.catalina.manager.HTMLManagerServlet.doGet(catalina-manager-5.5.23.jar.so) at javax.servlet.http.HttpServlet.service(tomcat5-servlet-2.4-api-5.5.23.jar.so) at javax.servlet.http.HttpServlet.service(tomcat5-servlet-2.4-api-5.5.23.jar.so) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(catalina-5.5.23.jar.so) at org.apache.catalina.core.ApplicationFilterChain.doFilter(catalina-5.5.23.jar.so) at org.apache.catalina.core.StandardWrapperValve.invoke(catalina-5.5.23.jar.so) at org.apache.catalina.core.StandardContextValve.invoke(catalina-5.5.23.jar.so) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(catalina-5.5.23.jar.so) at org.apache.catalina.core.StandardHostValve.invoke(catalina-5.5.23.jar.so) at org.apache.catalina.valves.ErrorReportValve.invoke(catalina-5.5.23.jar.so) at org.apache.catalina.core.StandardEngineValve.invoke(catalina-5.5.23.jar.so) at org.apache.catalina.connector.CoyoteAdapter.service(catalina-5.5.23.jar.so) at org.apache.coyote.http11.Http11Processor.process(tomcat-http-5.5.23.jar.so) at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(tomcat-http-5.5.23.jar.so) at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(tomcat-util-5.5.23.jar.so) at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(tomcat-util-5.5.23.jar.so) at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(tomcat-util-5.5.23.jar.so) at java.lang.Thread.run(libgcj.so.7rh)

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  • Mouse wheel not scrolling in JDialog but working in JFrame

    - by Iulian Serbanoiu
    Hello, I'm facing a frustrating issue. I have an application where the scroll wheel doesn't work in a JDialog window (but works in a JFrame). Here's the code: import javax.swing.*; import java.awt.event.*; public class Failtest extends JFrame { public static void main(String[] args) { new Failtest(); } public Failtest() { super(); setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); setTitle("FRAME"); JScrollPane sp1 = new JScrollPane(getNewList()); add(sp1); setSize(150, 150); setVisible(true); JDialog d = new JDialog(this, false);// NOT WORKING //JDialog d = new JDialog((JFrame)null, false); // NOT WORKING //JDialog d = new JDialog((JDialog)null, false);// WORKING - WHY? d.setTitle("DIALOG"); d.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE); JScrollPane sp = new JScrollPane(getNewList()); d.add(sp); d.setSize(150, 150); d.setVisible(true); } public JList getNewList() { String objs[] = new String[30]; for(int i=0; i<objs.length; i++) { objs[i] = "Item "+i; } JList l = new JList(objs); return l; } } I found a solution which is present as a comment in the java code - the constructor receiving a (JDialog)null parameter. Can someone enlighten me? My opinion is that this is a java bug. Tested on Windows XP-SP3 with 1 JDK and 2 JREs: D:\Program Files\Java\jdk1.6.0_17\bin>javac -version javac 1.6.0_17 D:\Program Files\Java\jdk1.6.0_17\bin>java -version java version "1.6.0_17" Java(TM) SE Runtime Environment (build 1.6.0_17-b04) Java HotSpot(TM) Client VM (build 14.3-b01, mixed mode, sharing) D:\Program Files\Java\jdk1.6.0_17\bin>cd .. D:\Program Files\Java\jdk1.6.0_17>java -version java version "1.6.0_18" Java(TM) SE Runtime Environment (build 1.6.0_18-b07) Java HotSpot(TM) Client VM (build 16.0-b13, mixed mode, sharing) Thank you in advance, Iulian Serbanoiu PS: The problem is not new - the code is taken from a forum (here) where this problem was also mentioned - but no solutions to it (yet) LATER EDIT: The problem persists with jre/jdk_1.6.0_10, 1.6.0_16 also LATER EDIT 2: Back home, tested on linux (Ubuntu - lucid/lynx) - both with openjdk and sun-java from distribution repo and it works (I used the .class file compiled on Windows) !!! - so I believe I'm facing a JRE bug that happens on some Windows configurations.

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  • Error when compiling code with the Protege API

    - by Anto
    I am new to Protege API and I have just created on Eclipse a small application which uses an external OWL file. Also I did import all the necessary libraries. import java.util.Collection; import java.util.Iterator; import edu.stanford.smi.protege.exception.OntologyLoadException; import edu.stanford.smi.protegex.owl.ProtegeOWL; import edu.stanford.smi.protegex.owl.model.*; public class Trial { public static void main(String[] args) throws OntologyLoadException{ String uri = "C:/Documents and Settings/Anto/Desktop/travel.owl"; OWLModel owlModel = ProtegeOWL.createJenaOWLModelFromURI(uri); Collection classes = owlModel.getUserDefinedOWLNamedClasses(); for(Iterator it = classes.iterator(); it.hasNext();){ OWLNamedClass cls = (OWLNamedClass) it.next(); Collection instances = cls.getInstances(false); System.out.println("Class " + cls.getBrowserText()+ " (" + instances.size()+")"); for(Iterator jt = instances.iterator(); jt.hasNext();){ OWLIndividual individual = (OWLIndividual) jt.next(); System.out.println(" - "+ individual.getBrowserText()); } } } } When I do compile however I get the following errors: WARNING: [Local Folder Repository] The specified file must be a directory. (C:\Documents and Settings\Anto\My Documents\Eclipse Workspace\ProtegeTrial\plugins\edu.stanford.smi.protegex.owl) LocalFolderRepository.update() SEVERE: Exception caught -- java.net.URISyntaxException: Illegal character in path at index 12: C:/Documents and Settings/CiuffreA/Desktop/travel.owl at java.net.URI$Parser.fail(URI.java:2809) at java.net.URI$Parser.checkChars(URI.java:2982) at java.net.URI$Parser.parseHierarchical(URI.java:3066) at java.net.URI$Parser.parse(URI.java:3014) at java.net.URI.<init>(URI.java:578) at edu.stanford.smi.protegex.owl.jena.JenaKnowledgeBaseFactory.getFileURI(Unknown Source) at edu.stanford.smi.protegex.owl.jena.JenaKnowledgeBaseFactory.loadKnowledgeBase(Unknown Source) at edu.stanford.smi.protege.model.Project.loadDomainKB(Unknown Source) at edu.stanford.smi.protege.model.Project.createDomainKnowledgeBase(Unknown Source) at edu.stanford.smi.protegex.owl.jena.creator.OwlProjectFromUriCreator.create(Unknown Source) at edu.stanford.smi.protegex.owl.ProtegeOWL.createJenaOWLModelFromURI(Unknown Source) at Trial.main(Trial.java:14) Exception in thread "main" java.lang.NullPointerException at edu.stanford.smi.protegex.owl.jena.JenaKnowledgeBaseFactory.loadKnowledgeBase(Unknown Source) at edu.stanford.smi.protege.model.Project.loadDomainKB(Unknown Source) at edu.stanford.smi.protege.model.Project.createDomainKnowledgeBase(Unknown Source) at edu.stanford.smi.protegex.owl.jena.creator.OwlProjectFromUriCreator.create(Unknown Source) at edu.stanford.smi.protegex.owl.ProtegeOWL.createJenaOWLModelFromURI(Unknown Source) at Trial.main(Trial.java:14) Does anyone have an idea on where the problem should be?

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  • Android Uncaught Exception

    - by Agrim Asthana
    09-30 02:32:31.474: D/ddm-heap(214): Got feature list request 09-30 02:32:31.634: D/AndroidRuntime(214): Shutting down VM 09-30 02:32:31.634: W/dalvikvm(214): threadid=3: thread exiting with uncaught exception (group=0x4001b188) 09-30 02:32:31.634: E/AndroidRuntime(214): Uncaught handler: thread main exiting due to uncaught exception 09-30 02:32:31.654: E/AndroidRuntime(214): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.mjcet.mjcet/com.mjcet.mjcet.MJCET}: java.lang.ClassNotFoundException: com.mjcet.mjcet.MJCET in loader dalvik.system.PathClassLoader@44e8c820 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2417) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread.access$2200(ActivityThread.java:119) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.os.Handler.dispatchMessage(Handler.java:99) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.os.Looper.loop(Looper.java:123) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread.main(ActivityThread.java:4363) 09-30 02:32:31.654: E/AndroidRuntime(214): at java.lang.reflect.Method.invokeNative(Native Method) 09-30 02:32:31.654: E/AndroidRuntime(214): at java.lang.reflect.Method.invoke(Method.java:521) 09-30 02:32:31.654: E/AndroidRuntime(214): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 09-30 02:32:31.654: E/AndroidRuntime(214): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 09-30 02:32:31.654: E/AndroidRuntime(214): at dalvik.system.NativeStart.main(Native Method) 09-30 02:32:31.654: E/AndroidRuntime(214): Caused by: java.lang.ClassNotFoundException: com.mjcet.mjcet.MJCET in loader dalvik.system.PathClassLoader@44e8c820 09-30 02:32:31.654: E/AndroidRuntime(214): at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:243) 09-30 02:32:31.654: E/AndroidRuntime(214): at java.lang.ClassLoader.loadClass(ClassLoader.java:573) 09-30 02:32:31.654: E/AndroidRuntime(214): at java.lang.ClassLoader.loadClass(ClassLoader.java:532) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.Instrumentation.newActivity(Instrumentation.java:1021) 09-30 02:32:31.654: E/AndroidRuntime(214): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2409) 09-30 02:32:31.654: E/AndroidRuntime(214): ... 11 more 09-30 02:32:31.684: I/dalvikvm(214): threadid=7: reacting to signal 3 09-30 02:32:31.684: E/dalvikvm(214): Unable to open stack trace file '/data/anr/traces.txt': Permission denied the above is my debugging output for the below activities LOGINACTIVITY.java package com.agrim.mjcet; import com.agrim.mjcet.R; import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.view.View; //import android.widget.TextView; import android.widget.Button; import android.widget.EditText; import android.view.View.OnClickListener; public class LoginActivity extends Activity { EditText txtUserName; EditText txtPassword; Button btnLogin; Button btnCancel; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // setting default screen to login.xml setContentView(R.layout.main); txtUserName=(EditText)this.findViewById(R.id.txtUname); txtPassword=(EditText)this.findViewById(R.id.txtPwd); btnLogin=(Button)this.findViewById(R.id.btnLogin); btnLogin=(Button)this.findViewById(R.id.btnLogin); btnLogin.setOnClickListener(new OnClickListener() { public void onClick(View v) { // Switching to Register screen if((txtUserName.getText().toString()).equals(txtPassword.getText().toString())) { Intent myIntent = new Intent(getApplicationContext(),SampleActivity.class); startActivityForResult(myIntent, 0); } } } ); } } SAMPLE ACTIVITY.java package com.agrim.mjcet; import com.agrim.mjcet.R; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.widget.TextView; public class SampleActivity extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Set View to register.xml setContentView(R.layout.lol); TextView HomeScreen = (TextView) findViewById(R.id.back); HomeScreen.setOnClickListener(new View.OnClickListener() { public void onClick(View arg0) { // Closing registration screen // Switching to Login Screen/closing register screen finish(); } }); } } and here are my 2 layouts MAIN.XML <TableLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:background="#000000" android:stretchColumns="1"> <TableRow> <TextView android:text="@string/user_name" android:textColor="#347235" android:id="@+id/TextView01" android:layout_width="wrap_content" android:layout_marginLeft="25dip" android:layout_height="wrap_content"> </TextView> <EditText android:text="" android:inputType="text" android:id="@+id/txtUname" android:layout_weight="0.75" android:layout_width="wrap_content" android:layout_marginRight="10dip" android:layout_marginBottom="5dip" android:background="#FFFFFF" android:layout_height="wrap_content"> </EditText> </TableRow> <TableRow> <TextView android:text="@string/password" android:textColor="#347235" android:id="@+id/TextView02" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="25dip"> </TextView> <EditText android:text="" android:inputType="textPassword" android:id="@+id/txtPwd" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginRight="10dip" android:layout_weight="1" android:background="#FFFFFF" android:gravity="center"> </EditText> </TableRow> <TableRow> <Button android:id="@+id/btnLogin" android:layout_width="fill_parent" android:layout_height="wrap_content" android:background="#FFFFFF" android:layout_marginTop="25dip" android:layout_marginLeft="50dip" android:onClick="onClickMyButton" android:text="@string/login" /> <Button android:id="@+id/btnCancel" android:layout_width="fill_parent" android:layout_height="wrap_content" android:background="#FFFFFF" android:layout_marginTop="25dip" android:layout_marginLeft="100dip" android:layout_marginRight="50dip" android:text="@string/cancel" /> </TableRow> <FrameLayout android:layout_width="wrap_content" android:layout_height="match_parent" > <ImageView android:layout_width="fill_parent" android:layout_height="match_parent" android:scaleType="centerInside" android:src="@drawable/logo_invert" android:contentDescription="@drawable/logo_invert"/> </FrameLayout> </TableLayout> and finally LOL.xml <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:background="#000000" android:layout_height="fill_parent" > <ImageView android:layout_width="fill_parent" android:id="@+id/back" android:layout_height="match_parent" android:scaleType="centerInside" android:src="@drawable/lol" android:contentDescription="@drawable/lol"> </ImageView> <RelativeLayout android:layout_width="match_parent" android:layout_height="138dp" android:orientation="vertical" android:gravity="bottom" > <TextView android:id="@+id/TextView02" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:layout_centerHorizontal="true" android:text="@string/coming_soon" android:textColor="#347235" /> </RelativeLayout> </FrameLayout> I get a force close upon initialization.. and yes this is my first android app :)

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  • NullPointerException using datanucleus-json with S3

    - by Matt
    I'm using datanucleus 3.2.7 from Maven, trying to use the Amazon S3 JPA provider. I can successfully write data into S3, but querying either by using "SELECT u FROM User u" or "SELECT u FROM User u WHERE id = :id" causes a NullPointerException to be thrown. Using the RDBMS provider, everything works perfectly. Is there something I'm doing wrong? Main.java EntityManagerFactory factory = Persistence.createEntityManagerFactory("MyUnit"); EntityManager entityManager = factory.createEntityManager(); Query query = entityManager.createQuery("SELECT u FROM User u", User.class); List<User> users = query.getResultList(); // Null pointer exception here for(User u:users) System.out.println(u); User.java package test; import javax.persistence.*; @Entity @Table(name = "User") public class User { @Id public String id; public String name; public User(String id, String name) { this.id = id; this.name = name; } public String toString() { return id+" : "+name; } } persistence.xml <?xml version="1.0" encoding="UTF-8" ?> <persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" version="1.0"> <persistence-unit name="MyUnit"> <class>test.User</class> <exclude-unlisted-classes /> <properties> <properties> <property name="datanucleus.ConnectionURL" value="amazons3:http://s3.amazonaws.com/" /> <property name="datanucleus.ConnectionUserName" value="xxxxx" /> <property name="datanucleus.ConnectionPassword" value="xxxxx" /> <property name="datanucleus.cloud.storage.bucket" value="my-bucket" /> </properties> <property name="datanucleus.autoCreateSchema" value="true" /> </properties> </persistence-unit> </persistence> Exception java.lang.NullPointerException at org.datanucleus.NucleusContext.isClassWithIdentityCacheable(NucleusContext.java:1840) at org.datanucleus.ExecutionContextImpl.getObjectFromLevel2Cache(ExecutionContextImpl.java:5287) at org.datanucleus.ExecutionContextImpl.getObjectFromCache(ExecutionContextImpl.java:5191) at org.datanucleus.ExecutionContextImpl.findObject(ExecutionContextImpl.java:3137) at org.datanucleus.store.json.CloudStoragePersistenceHandler.getObjectsOfCandidateType(CloudStoragePersistenceHandler.java:367) at org.datanucleus.store.json.query.JPQLQuery.performExecute(JPQLQuery.java:94) at org.datanucleus.store.query.Query.executeQuery(Query.java:1786) at org.datanucleus.store.query.Query.executeWithMap(Query.java:1690) at org.datanucleus.api.jpa.JPAQuery.getResultList(JPAQuery.java:194) at test.Main.main(Main.java:16)

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  • How to create Executable Jar

    - by Siddharth
    When I try to create a jar file i found the following error, so please someone help me to out of this. Exception in thread "LWJGL Application" com.badlogic.gdx.utils.GdxRuntimeException: Couldn't load file: img/black_ring.png at com.badlogic.gdx.graphics.Pixmap.(Pixmap.java:137) at com.badlogic.gdx.graphics.glutils.FileTextureData.prepare(FileTextureData.java:55) at com.badlogic.gdx.graphics.Texture.load(Texture.java:175) at com.badlogic.gdx.graphics.Texture.create(Texture.java:159) at com.badlogic.gdx.graphics.Texture.(Texture.java:133) at com.badlogic.gdx.graphics.Texture.(Texture.java:122) at com.badlogic.runningball.UserBall.(UserBall.java:19) at com.badlogic.runningball.GameScreen.(GameScreen.java:25) at com.badlogic.runningball.RunningBall.create(RunningBall.java:12) at com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop(LwjglApplication.java:126) at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:113) Caused by: com.badlogic.gdx.utils.GdxRuntimeException: File not found: img/black_ring.png (Internal) at com.badlogic.gdx.files.FileHandle.read(FileHandle.java:108) at com.badlogic.gdx.files.FileHandle.length(FileHandle.java:364) at com.badlogic.gdx.files.FileHandle.readBytes(FileHandle.java:156) at com.badlogic.gdx.graphics.Pixmap.(Pixmap.java:134) ... 10 more

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  • Java Developers: Is Ant still in the "main stream" for builds? Do we push new developers to learn it?

    - by Sam Goldberg
    We have been slowly replacing batch command files (windows .bat) which were simply jarring up the classes compiled in the developers IDE, with more comprehensive Ant builds (i.e. get from CVS, clean compile, jar, archive, email, etc.) I've spent a lot of time learning (and debugging issues) with Ant, so I'm most comfortable using it for these tasks. But I wonder if Ant is still in as wide usage as it was when I first started learning, or whether "the world has moved on" to something newer (and maybe slicker). (I've started to see more Maven build stuff distributed, which I've never used, for example.) The practical import of this question, is whether I push new developers to learn Ant, or whether they should be learning something else for builds? I'm never too on top of the trends, so it would be great to hear from other Java developers what they think is the best build tool, and what they think new developers should be learning.

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  • Wide gap in my resume as a Java developer. What are must-have skills required to get hired those days? [closed]

    - by OnlineAlien
    For some legal reasons I haven't worked for anybody for the last 12 years. I am a java web developer or at least I am thinking so. For this period I have been working on my project- some sort of business network - and I did few small jobs, so right now I feel I am far behind in terms of my skills and the skills needed today. I lingered too long on Struts and Hibernate and thought that could the job for my project. I need to get a job, right now, so I am spending most of my time brushing my skills. My question is: What are the current necessary skills that could convince employers to hire me regardless of my past employment or the lack of it. Right now I am on AspectJ, IoC and Spring Thanks

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  • JPA 2?EJB 3.1?JSF 2????????! WebLogic Server 12c?????????Java EE 6??????|WebLogic Channel|??????

    - by ???02
    ????????????????????????????????????????·???????????Java EE 6???????????????·????WebLogic Server 12c?(???)?????????Oracle Enterprise Pack for Eclipse 12c?????Java EE 6??????3???????????????????????JSF 2.0?????????????????????????JAX-RS????RESTful?Web???????????????(???)?????????????JSF 2.0???????????????? Java EE 6??????????????????????????????????????JSF(JavaServer Faces) 2.0??????????Java EE?????????????????????????????????Struts????????????????????????????????JSF 2.0?Java EE 6??????????????????????????????????????????????????JSP(JavaServer Pages)?JSF???????????????????????·???????????????????????Web???????????????????????????????????????????????????????????????????????????????? ???????????????????????????????EJB??????????????EMPLOYEES??????????????????????XHTML????????????????????????????????????????????????????????????ManagedBean????????????JSF 2.0????????????????????? ?????????Oracle Enterprise Pack for Eclipse(OEPE)?????????????????Eclipse(OEPE)???????·?????OOW?????????????????·???????????Properties?????????????????·???·????????????????????????????Project Facets????????????JavaServer Faces?????????????Apply?????????OK???????????? ???JSF????????????????????????????ManagedBean???IndexBean?????????????OOW??????????????????·???????????????NEW?-?Class??????New Java Class??????????????????????Package????managed???Name????IndexBean???????Finish???????????? ?????IndexBean??????·????????????????????????????????????????????IndexBean(IndexBean.java)?package managed;import java.util.ArrayList;import java.util.List;import javax.ejb.EJB;import javax.faces.bean.ManagedBean;import ejb.EmpLogic;import model.Employee;@ManagedBeanpublic class IndexBean {  @EJB  private EmpLogic empLogic;  private String keyword;  private List<Employee> results = new ArrayList<Employee>();  public String getKeyword() {    return keyword;  }  public void setKeyword(String keyword) {    this.keyword = keyword;  }  public List getResults() {    return results;  }  public void actionSearch() {    results.clear();    results.addAll(empLogic.getEmp(keyword));  }} ????????????????keyword?results??????????????????????????????Session Bean???EmpLogic?????????????????@EJB?????????????????????????????????????????????????????????????????????actionSearch??????????????EmpLogic?????????·????????????????????result???????? ???ManagedBean?????????????????????????????????????????·??????OOW??????????????WebContent???????index.xhtml????? ???????????index.xhtml????????????????????????????????????????????????(Index.xhtml)?<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"  xmlns:ui="http://java.sun.com/jsf/facelets"  xmlns:h="http://java.sun.com/jsf/html"  xmlns:f="http://java.sun.com/jsf/core"><h:head>  <title>Employee??????</title></h:head><h:body>  <h:form>    <h:inputText value="#{indexBean.keyword}" />    <h:commandButton action="#{indexBean.actionSearch}" value="??" />    <h:dataTable value="#{indexBean.results}" var="emp" border="1">      <h:column>        <f:facet name="header">          <h:outputText value="employeeId" />        </f:facet>        <h:outputText value="#{emp.employeeId}" />      </h:column>      <h:column>        <f:facet name="header">          <h:outputText value="firstName" />        </f:facet>        <h:outputText value="#{emp.firstName}" />      </h:column>      <h:column>        <f:facet name="header">          <h:outputText value="lastName" />        </f:facet>        <h:outputText value="#{emp.lastName}" />      </h:column>      <h:column>        <f:facet name="header">          <h:outputText value="salary" />        </f:facet>        <h:outputText value="#{emp.salary}" />      </h:column>    </h:dataTable>  </h:form></h:body></html> index.xhtml???????????????????ManagedBean???IndexBean??????????????????????????????IndexBean?????actionSearch??????????h:commandButton???????????????????????????????????????? ???Web???????????????(web.xml)??????web.xml???????·?????OOW???????????WebContent?-?WEB-INF?????? ?????????????web-app??????????????welcome-file-list(????)?????????????Web???????????????(web.xml)?<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:javaee="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="3.0">  <javaee:display-name>OOW</javaee:display-name>  <servlet>    <servlet-name>Faces Servlet</servlet-name>    <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>    <load-on-startup>1</load-on-startup>  </servlet>  <servlet-mapping>    <servlet-name>Faces Servlet</servlet-name>    <url-pattern>/faces/*</url-pattern>  </servlet-mapping>  <welcome-file-list>    <welcome-file>/faces/index.xhtml</welcome-file>  </welcome-file-list></web-app> ???JSF????????????????????????????? ??????Java EE 6?JPA 2.0?EJB 3.1?JSF 2.0????????????????????????????????????????????????????????????????·?????OOW???????????·???????????????Run As?-?Run on Server??????????????????????????????????????????????????????????Oracle WebLogic Server 12c(12.1.1)??????Next??????????????? ?????????????????????Domain Directory??????Browse????????????????????????C:\Oracle\Middleware\user_projects\domains\base_domain??????Finish???????????? ?????WebLogic Server?????????????????????????????????????????????????????????????????????OEPE??Servers???????Oracle WebLogic Server 12c???????????·???????????????Properties??????????????????????????????WebLogic?-?Publishing????????????Publish as an exploded archive??????????????????OK???????????? ???????????????????????????????????????????·?????OOW???????????·???????????????Run As?-?Run on Server??????????????????Finish???????????? ???????????????????????????????????????????????·??????????????????????????????????????????firstName?????????????????JAX-RS???RESTful?Web??????? ?????????JAX-RS????RESTful?Web??????????????? Java EE??????????Java EE 5???SOAP????Web??????????JAX-WS??????????Java EE 6????????JAX-RS?????????????RESTful?Web????????????·????????????????????????JAX-RS????????Session Bean??????·?????????Web???????????????????????????????????????????????JAX-RS?????????? ?????????????????????????????JAX-RS???RESTful Web??????????????????????????·?????OOW???????????·???????????????Properties???????????????????????????Project Facets?????????????JAX-RS(Rest Web Services)???????????Further configuration required?????????????Modify Faceted Project???????????????JAX-RS??????·?????????????????JAX-RS Implementation Library??????Manage libraries????(???????????)?????????????? ??????Preference(Filtered)???????????????New????????????????New User Library????????????????User library name????JAX-RS???????OK???????????????????Preference(Filtered)?????????????Add JARs????????????????????????C:\Oracle\Middleware\modules \com.sun.jersey.core_1.1.0.0_1-9.jar??????OK???????????? ???Modify Faceted Project??????????JAX-RS Implementation Library????JAX-RS????????????????????JAX-RS servlet class name????com.sun.jersey.spi.container.servlet.ServletContainer???????OK?????????????Project Facets???????????????????OK?????????????????? ???RESTful Web??????????????????????????????????(???????EmpLogic?????????????)??RESTful Web?????????????EmpLogic(EmpLogic.java)?package ejb; import java.util.List; import javax.ejb.LocalBean; import javax.ejb.Stateless; import javax.persistence.EntityManager; import javax.persistence.PersistenceContext; import javax.ws.rs.GET;import javax.ws.rs.Path;import javax.ws.rs.PathParam;import javax.ws.rs.Produces;import model.Employee; @Stateless @LocalBean @Path("/emprest")public class EmpLogic {     @PersistenceContext(unitName = "OOW")     private EntityManager em;     public EmpLogic() {     }  @GET  @Path("/getname/{empno}")  // ?  @Produces("text/plain")  // ?  public String getEmpName(@PathParam("empno") long empno) {    Employee e = em.find(Employee.class, empno);    if (e == null) {      return "no data.";    } else {      return e.getFirstName();    }  }} ?????????????????????@Path("/emprest ")????????????RESTful Web????????????HTTP??????????????JAX-RS????????????????????????RESTful Web?????Web??????????????????@Produces???????(?)??????????????????????????text/plain????????????????????????????application/xml?????????XML???????????application/json?????JSON?????????????????? ???????????????Web???????????????????????????????????????·?????OOW???????????·???????????????Run As?-?Run on Server??????????????????Finish???????????????????Web??????http://localhost:7001/OOW/jaxrs/emprest/getname/186????????????????URL?????????(186)?employeeId?????????????firstName????????????????*    *    * ????????3??????WebLogic Server 12c?OEPE????Java EE 6?????????????????Java EE 6????????????????·????????????????????????????Java EE?????????????????????????????????????????????????????????????????????????????????

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  • Java Plist XML Parsing

    - by Jannis
    Hello everyone, I'm parsing a (not well formed) Apple Plist File with java. My Code looks like this: InputStream in = new FileInputStream( "foo" ); XMLInputFactory factory = XMLInputFactory.newInstance(); XMLEventReader parser = factory.createXMLEventReader( in ); while (parser.hasNext()){ XMLEvent event = parser.nextEvent(); //code to navigate the nodes } The parts I"m parsing are looking like this: <dict> <key>foo</key><integer>123</integer> <key>bar</key><string>Boom &amp; Shroom</string> </dict> My problem is now, that nodes containing a ampersand are not parsed like they should because the ampersand is representing a entity. What can i do to get the value of the node as a complete String, instead of broken parts? Thank you in advance.

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