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  • Trying to write a loop that uses an OutputStream to write to a text file.

    - by Steve McLain
    I'm not a java programmer, I'm a VB programmer. I am doing this as part of an assignment, however, I'm not asking for help on something assignment related. I'd like to figure out how to get the OutputStreamWriter to work properly in this instance. I just want to capture the values I'm generating and place them into a text document. The file is generated, but only one entry exists, not the 40 I'm expecting. I could do this in a heartbeat with VB, but java feels very strange to me right now. Your help is appreciated. Thanks, Steve Here's the code: public static void main(String[] args){ long start, end; double result,difference; try {//OutputStream code assistance from http://tutorials.jenkov.com/java-io/outputstreamwriter.html OutputStream outputStream = new FileOutputStream("c:\\Temp\\output1.txt"); Writer out = new OutputStreamWriter(outputStream); for(int n=1; n<=20; n++){ //Calculate the Time for n^2. start = System.nanoTime(); //Add code to call method to calculate n^2 result = mN2(n); end = System.nanoTime(); difference = (end - start); //Output results to a file out.write("N^2 End time: " + end + " Difference: " + difference + "\n"); out.close(); } } catch (IOException e){ } try { OutputStream outputStream = new FileOutputStream("c:\\Temp\\output1.txt"); Writer out = new OutputStreamWriter(outputStream); for(int n=1; n<=20; n++){ //Calculate the Time for 2^n. start = System.nanoTime(); //Add code to call method to calculate 2^n result = m2N(n); end = System.nanoTime(); difference = (end - start); //Output results to a file out.write("N^2 End time: " + end + " Difference: " + difference + "\n"); out.close(); } } catch (IOException e){ } } //Calculate N^2 public static double mN2(double n) { n = n*n; return n; } //Calculate 2N public static double m2N (double n) { n = 2*n; return n; }

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  • Synchronizing thread communication?

    - by Roger Alsing
    Just for the heck of it I'm trying to emulate how JRuby generators work using threads in C#. Also, I'm fully aware that C# haas built in support for yield return, I'm just toying around a bit. I guess it's some sort of poor mans coroutines by keeping multiple callstacks alive using threads. (even though none of the callstacks should execute at the same time) The idea is like this: The consumer thread requests a value The worker thread provides a value and yields back to the consumer thread Repeat untill worker thread is done So, what would be the correct way of doing the following? //example class Program { static void Main(string[] args) { ThreadedEnumerator<string> enumerator = new ThreadedEnumerator<string>(); enumerator.Init(() => { for (int i = 1; i < 100; i++) { enumerator.Yield(i.ToString()); } }); foreach (var item in enumerator) { Console.WriteLine(item); }; Console.ReadLine(); } } //naive threaded enumerator public class ThreadedEnumerator<T> : IEnumerator<T>, IEnumerable<T> { private Thread enumeratorThread; private T current; private bool hasMore = true; private bool isStarted = false; AutoResetEvent enumeratorEvent = new AutoResetEvent(false); AutoResetEvent consumerEvent = new AutoResetEvent(false); public void Yield(T item) { //wait for consumer to request a value consumerEvent.WaitOne(); //assign the value current = item; //signal that we have yielded the requested enumeratorEvent.Set(); } public void Init(Action userAction) { Action WrappedAction = () => { userAction(); consumerEvent.WaitOne(); enumeratorEvent.Set(); hasMore = false; }; ThreadStart ts = new ThreadStart(WrappedAction); enumeratorThread = new Thread(ts); enumeratorThread.IsBackground = true; isStarted = false; } public T Current { get { return current; } } public void Dispose() { enumeratorThread.Abort(); } object System.Collections.IEnumerator.Current { get { return Current; } } public bool MoveNext() { if (!isStarted) { isStarted = true; enumeratorThread.Start(); } //signal that we are ready to receive a value consumerEvent.Set(); //wait for the enumerator to yield enumeratorEvent.WaitOne(); return hasMore; } public void Reset() { throw new NotImplementedException(); } public IEnumerator<T> GetEnumerator() { return this; } System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { return this; } } Ideas?

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  • Output on namespaced xpath in java

    - by user347928
    I have the following code and have had some trouble with a specific field and it's output. The namespace is connected but doesn't seem to be outputting on the required field. Any info on this would be great. import org.w3c.dom.Document; import org.xml.sax.SAXException; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.ParserConfigurationException; import javax.xml.xpath.XPathFactory; import javax.xml.xpath.XPath; import javax.xml.xpath.XPathExpressionException; import java.io.ByteArrayInputStream; import java.io.IOException; public class test { public static void main(String args[]) { String xmlStr = "<aws:UrlInfoResponse xmlns:aws=\"http://alexa.amazonaws.com/doc/2005-10-05/\">\n" + " <aws:Response xmlns:aws=\"http://awis.amazonaws.com/doc/2005-07-11\">\n" + " <aws:OperationRequest>\n" + " <aws:RequestId>blah</aws:RequestId>\n" + " </aws:OperationRequest>\n" + " <aws:UrlInfoResult>\n" + " <aws:Alexa>\n" + " <aws:TrafficData>\n" + " <aws:DataUrl type=\"canonical\">harvard.edu/</aws:DataUrl>\n" + " <aws:Rank>1635</aws:Rank>\n" + " </aws:TrafficData>\n" + " </aws:Alexa>\n" + " </aws:UrlInfoResult>\n" + " <aws:ResponseStatus xmlns:aws=\"http://alexa.amazonaws.com/doc/2005-10-05/\">\n" + " <aws:StatusCode>Success</aws:StatusCode>\n" + " </aws:ResponseStatus>\n" + " </aws:Response>\n" + "</aws:UrlInfoResponse>"; DocumentBuilderFactory xmlFact = DocumentBuilderFactory.newInstance(); xmlFact.setNamespaceAware(true); DocumentBuilder builder = null; try { builder = xmlFact.newDocumentBuilder(); } catch (ParserConfigurationException e) { e.printStackTrace(); } Document doc = null; try { doc = builder.parse( new ByteArrayInputStream( xmlStr.getBytes())); } catch (SAXException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } System.out.println(doc.getDocumentElement().getNamespaceURI()); System.out.println(xmlFact.isNamespaceAware()); String xpathStr = "//aws:OperationRequest"; XPathFactory xpathFact = XPathFactory.newInstance(); XPath xpath = xpathFact.newXPath(); String result = null; try { result = xpath.evaluate(xpathStr, doc); } catch (XPathExpressionException e) { e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates. } System.out.println("XPath result is \"" + result + "\""); } }

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  • How to extract the word and line wrapping information from JTextArea for text with given font

    - by Gábor Lipták
    I have to convert styled text to wrapped simple text (for SVG word wrapping). I cannot beleive that the word wrapping information (how many lines are there, where are the line breaks) cannot be extracted from the JTextArea. So I created a small frame program: package bla; import java.awt.BorderLayout; import java.awt.Color; import java.awt.Font; import java.awt.Frame; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import java.util.ArrayList; import java.util.List; import javax.swing.JTextArea; public class Example1 extends WindowAdapter { private static String content = "01234567890123456789\n" + "0123456 0123456 01234567 01234567"; JTextArea text; public Example1() { Frame f = new Frame("TextArea Example"); f.setLayout(new BorderLayout()); Font font = new Font("Serif", Font.ITALIC, 20); text = new JTextArea(); text.setFont(font); text.setForeground(Color.blue); text.setLineWrap(true); text.setWrapStyleWord(true); f.add(text, BorderLayout.CENTER); text.setText(content); // Listen for the user to click the frame's close box f.addWindowListener(this); f.setSize(100, 511); f.show(); } public static List<String> getLines( JTextArea text ) { //WHAT SHOULD I WRITE HERE return new ArrayList<String>(); } public void windowClosing(WindowEvent evt) { List<String> lines = getLines(text); System.out.println( "Number of lines:" + lines.size()); for (String line : lines) { System.out.println( line ); } System.exit(0); } public static void main(String[] args) { Example1 instance = new Example1(); } } If you run it you will see this: And what I expect as output: Number of lines:6 0123456789 0123456789 0123456 0123456 01234567 01234567 What should I write in place of the comment?

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  • Can output from OutputDebugString be viewed in VisualStudio's output window

    - by wageoghe
    I am using C# and VS2010. When I use OutputDebugString to write debug information, should it show up in the output window? I can see the output from OutputDebugString in DebugView, but I thought I would see it in Visual Studio's Output window. I have looked under Tools-Options-Debugging-General and the output is NOT being redirected to the Immediate window. I have also looked under Tools-Options-Debugging-Output Window and all General Output Settings are set to "On". Finally, I have used the drop-down list in the Output window to specify that Debug messages should appear. If I change Tools-Options-Debugging-General to redirect the output to the Immediate window, the OutputDebugString messages do not appear in the immediate window. Here is my entire test program: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Runtime.InteropServices; using System.Diagnostics; namespace OutputDebugString { class Program { [DllImport("kernel32.dll", CharSet = CharSet.Auto)] public static extern void OutputDebugString(string message); static void Main(string[] args) { Console.WriteLine("Main - Enter - Console.WriteLine"); Debug.WriteLine("Main - Enter - Debug.WriteLine"); OutputDebugString("Main - Enter - OutputDebugString"); OutputDebugString("Main - Exit - OutputDebugString"); Debug.WriteLine("Main - Exit - Debug.WriteLine"); Console.WriteLine("Main - Exit - Console.WriteLine"); } } } If I run within the debugger, the Debug.WriteLine output does show up in the output window, but the OutputDebugString output does not. If I run from a console window, both Debug.WriteLine and OutputDebugString show up in DebugView. Why doesn't the OutputDebugString output ever show up in the output window? Ultimately, my intent is not to write a lot of debug output with OutputDebugString, rather I will use System.Diagnostics or NLog or something similar. I am just trying to find out, if I configure a logging platform to write to OutputDebugString, will the output be visible from within the debugger. Edit: I went back to my original program (not the simple test above) which uses TraceSources and TraceListeners configured via the app.config file. If I configure the trace sources to write to the System.Diagnostics.DefaultTraceListener (which is documented as writing to OutputDebugString), then the trace source output DOES go to the debug window. However, lines that write directly with OutputDebugString (such as in my simple example) DO NOT go to the debug window. Also, if I use a different TraceListener that writes to OutputDebugString (I got one from Ukadc.Diagnostics at codeplex), that output DOES NOT go to the debug window. Note that I have seen these questions but they did not provide a working solution: here and here

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  • mulformed Farsi characters on AWT

    - by jlover2010
    Hi As i started programming by jdk6, i had no problem in text components neither in awt nor in swing. But for labels or titles of awt components, yes : I couldn't have Farsi characters displayable on AWTs just as simple as Swing by typing them into the source code. lets check this SSCCE : import javax.swing.*; import java.awt.*; import java.io.*; import java.util.Properties; public class EmptyFarsiCharsOnAWT extends JFrame{ public EmptyFarsiCharsOnAWT() { super("????"); setDefaultCloseOperation(3); setVisible(rootPaneCheckingEnabled); } public static void main(String[] args) throws AWTException, IOException { JFrame jFrame = new EmptyFarsiCharsOnAWT(); MenuItem show ; // approach 1 = HardCoding : /* show = new MenuItem("\u0646\u0645\u0627\u06cc\u0634"); * */ // approach 2 = using simple utf-8 saved text file : /* BufferedReader in = new BufferedReader(new FileReader("farsiLabels.txt")); String showLabel = in.readLine(); in.close(); show = new MenuItem(showLabel); * */ // approach 3 = using properties file : FileReader in = new FileReader("farsiLabels.properties"); Properties farsiLabels = new Properties(); farsiLabels.load(in); show = new MenuItem(farsiLabels.getProperty("tray.show")); PopupMenu popUp = new PopupMenu(); popUp.add(show); // creating Tray object Image iconIamge = Toolkit.getDefaultToolkit().getImage("greenIcon.png"); TrayIcon trayIcon = new TrayIcon(iconIamge, null, popUp); SystemTray tray = SystemTray.getSystemTray(); tray.add(trayIcon); jFrame.setIconImage(iconIamge); } } Yes, i know each of three approaches in source code does right when you may test it from IDE , but if you make a JAR contains just this class (and its resources) by means of NetBeans project clean&build ,you won't see the expected characters and will just get EMPTY/BLANK SQUARES ! Unfortunately, opposed to other situations i encountered before, here there is no way to avoid using awt and make use of Swing in this case. And this was just an SSCCE i made to show the problem and my recent (also first) application suffers from this subject. And i think should have to let you know I posted this question a while ago in SDN and "the Java Ranch" forums and other native forums and still I'm watching... By the way i am using latest version of Netbeans IDE... I will be so grateful if anybody has a solution to this damn AWT components never rendered any Farsi character for me... Thanks in advance

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  • Decrypting data from a secure socket

    - by Ronald
    I'm working on a server application in Java. I've successfully got past the handshake portion of the communication process, but how do I go about decrypting my input stream? Here is how I set up my server: import java.io.IOException; import java.net.ServerSocket; import java.net.Socket; import java.util.ArrayList; import java.util.HashMap; import javax.net.ServerSocketFactory; import javax.net.ssl.SSLServerSocket; import javax.net.ssl.SSLServerSocketFactory; import org.json.me.JSONException; import dictionary.Dictionary; public class Server { private static int port = 1234; public static void main(String[] args) throws JSONException { System.setProperty("javax.net.ssl.keyStore", "src/my.keystore"); System.setProperty("javax.net.ssl.keyStorePassword", "test123"); System.out.println("Starting server on port: " + port); HashMap<String, Game> games = new HashMap<String, Game>(); final String[] enabledCipherSuites = { "SSL_RSA_WITH_RC4_128_SHA" }; try{ SSLServerSocketFactory socketFactory = (SSLServerSocketFactory) SSLServerSocketFactory.getDefault(); SSLServerSocket listener = (SSLServerSocket) socketFactory.createServerSocket(port); listener.setEnabledCipherSuites(enabledCipherSuites); Socket server; Dictionary dict = new Dictionary(); Game game = new Game(dict); //for testing, creates 1 global game. while(true){ server = listener.accept(); ClientConnection conn = new ClientConnection(server, game, "User"); Thread t = new Thread(conn); t.start(); } } catch(IOException e){ System.out.println("Failed setting up on port: " + port); e.printStackTrace(); } } } I used a BufferedReader to get the data send from the client: BufferedReader d = new BufferedReader(new InputStreamReader(socket.getInputStream())); After the handshake is complete it appears like I'm getting encrypted data. I did some research online and it seems like I might need to use a Cipher, but I'm not sure. Any ideas?

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  • How the simples GUI countdown is supposed to work?

    - by Roman
    I am trying to write the simples GUI countdown. I found in Internet some code but it is already too fancy for me. I am trying to keep it as simple as possible. So, I just want to have a window saying "You have 10 second left". The number of second should decrease every second from 10 to 0. I wrote a code. And I think I am close to the working solution. But I still missing something. Could you pleas help me to find out what is wrong? Here is my code: import javax.swing.*; public class Countdown { static JLabel label; // Method which defines the appearance of the window. private static void showGUI() { JFrame frame = new JFrame("Simple Countdown"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JLabel label = new JLabel("Some Text"); frame.add(label); frame.pack(); frame.setVisible(true); } // Define a new thread in which the countdown is counting down. static Thread counter = new Thread() { public void run() { for (int i=10; i>0; i=i-1) { updateGUI(i,label); try {Thread.sleep(1000);} catch(InterruptedException e) {}; } } }; // A method which updates GUI (sets a new value of JLabel). private static void updateGUI(final int i, final JLabel label) { SwingUtilities.invokeLater(new Runnable(i,label) { public Runnable(int i, JLabel label) { this.i = i; this.label = label; } public void run() { label.setText("You have " + i + " seconds."); } }); } // The main method (entry point). public static void main(String[] args) { javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { showGUI(); //counter.start(); } }); //counter.start(); } } And I have several concrete question about this code: Where should I place the counter.start();? (In my code I put it on 2 places. Which one is correct?) Why compiler complains about the constructor for Runnable? It says that I have an invalid method declaration and I need to specify the returned type. ADDED: I made the suggested corrections. And then I execute the code and get: Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at Worker.run(Worker.java:12) In the Worker.java in the line 12 I have: label.setText("You have " + i + " seconds.");.

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  • Constructor or Explicit cast

    - by Felan
    In working with Linq to Sql I create a seperate class to ferry data to a web page. To simplify creating these ferry objects I either use a specialized constructor or an explicit conversion operator. I have two questions. First which approach is better from a readibility perspective? Second while the clr code that is generated appeared to be the same to me, are there situations where one would be treated different than the other by the compiler (in lambda's or such). Example code (DatabaseFoo uses specialized constructor and BusinessFoo uses explicit operator): public class DatabaseFoo { private static int idCounter; // just to help with generating data public int Id { get; set; } public string Name { get; set; } public DatabaseFoo() { Id = idCounter++; Name = string.Format("Test{0}", Id); } public DatabaseFoo(BusinessFoo foo) { this.Id = foo.Id; this.Name = foo.Name; } } public class BusinessFoo { public int Id { get; set; } public string Name { get; set; } public static explicit operator BusinessFoo(DatabaseFoo foo) { return FromDatabaseFoo(foo); } public static BusinessFoo FromDatabaseFoo(DatabaseFoo foo) { return new BusinessFoo {Id = foo.Id, Name = foo.Name}; } } public class Program { static void Main(string[] args) { Console.WriteLine("Creating the initial list of DatabaseFoo"); IEnumerable<DatabaseFoo> dafoos = new List<DatabaseFoo>() { new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo(), new DatabaseFoo()}; foreach(DatabaseFoo dafoo in dafoos) Console.WriteLine(string.Format("{0}\t{1}", dafoo.Id, dafoo.Name)); Console.WriteLine("Casting the list of DatabaseFoo to a list of BusinessFoo"); IEnumerable<BusinessFoo> bufoos = from x in dafoos select (BusinessFoo) x; foreach (BusinessFoo bufoo in bufoos) Console.WriteLine(string.Format("{0}\t{1}", bufoo.Id, bufoo.Name)); Console.WriteLine("Creating a new list of DatabaseFoo by calling the constructor taking BusinessFoo"); IEnumerable<DatabaseFoo> fufoos = from x in bufoos select new DatabaseFoo(x); foreach(DatabaseFoo fufoo in fufoos) Console.WriteLine(string.Format("{0}\t{1}", fufoo.Id, fufoo.Name)); } }

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  • JPanel components paint-time problem

    - by Tom Brito
    I'm having a problem that when my frame is shown (after a login dialog) the buttons are not on correct position, then in some miliseconds they go to the right position (the center of the panel with border layout). When I make a SSCCE, it works correct, but when I run my whole code I have this fast-miliseconds delay to the buttons to go to the correct place. Unfortunately, I can't post the whole code, but the method that shows the frame is: public void login(JComponent userView) { centerPanel.removeAll(); centerPanel.add(userView); centerPanel.revalidate(); centerPanel.repaint(); frame.setVisible(true); } What would cause this delay to the panel layout? (I'm running everything in the EDT) -- update In my machine, this SSCCE shows the layout problem in 2 of 10 times I run it: import java.awt.BorderLayout; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.SwingUtilities; public class TEST { public static void main(String[] args) throws Exception { SwingUtilities.invokeAndWait(new Runnable() { @Override public void run() { System.out.println("Debug test..."); JPanel btnPnl = new JPanel(); btnPnl.add(new JButton("TEST")); JFrame f = new JFrame("TEST"); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.getContentPane().setLayout(new BorderLayout()); f.getContentPane().add(btnPnl); f.pack(); f.setSize(800, 600); f.setVisible(true); System.out.println("End debug test!"); } }); } } The button first appers in the up-left, and then it goes to the center. Please, note that I'm understand, not just correct. Is it a java bug? --update OK, so the SSCCE don't show the problem with you that tried till now. Maybe it's my computer performance problem. But this don't answer the question, I still think Java Swing is creating new threads for make the layout behind the scenes.

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  • How to pass parameters to Apache Pivot's wtkx:include tag?

    - by Andrew Swan
    I need to create a reusable UI component that accepts a number of parameters (e.g. an image URL and some label text), similar to how JSP tags can accept parameters. The Pivot docs for the "wtkx:include" tag say: The tag allows a WTKX file to embed content defined in an external WTKX file as if it was defined in the source file itself. This is useful for ... defining reusable content templates I was hoping that I could define my component in a WTKX file using standard Pivot components (e.g. a TextInput) and pass it one or more parameters; for example my reusable template called "row.wtkx" might contain a row with an image and a text field, like this (where the ${xxx} bits are the parameters): <TablePane.Row xmlns="org.apache.pivot.wtk"> <ImageView image="@images/${image_url}" /> <TextInput text="${title}" /> </TablePane.Row> I could then reuse this component within a TablePane as follows: <rows> <TablePane.Row> <Label text="Painting"/> <Label text="Title"/> </TablePane.Row> <wtkx:include src="row.wtkx" image_url="mona_lisa.jpg" title="Mona Lisa"/> <wtkx:include src="row.wtkx" image_url="pearl_earring.jpg" title="Girl with a Pearl Earring"/> <wtkx:include src="row.wtkx" image_url="melting_clocks.jpg" title="Melting Clocks"/> </rows> I've made up the ${...} syntax myself just to show what I'm trying to do. Also, there could be other ways to pass the parameter values other than using attributes of the "wtkx:include" tag itself, e.g. pass a JSON-style map called say "args". The ability to pass parameters like this would make the include tag much more powerful, e.g. in my case allow me to eliminate a lot of duplication between the table row declarations. Or is "wtkx:include" not the right way to be doing this?

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  • Exception when indexing text documents with Lucene, using SnowballAnalyzer for cleaning up

    - by Julia
    Hello!!! I am indexing the documents with Lucene and am trying to apply the SnowballAnalyzer for punctuation and stopword removal from text .. I keep getting the following error :( IllegalAccessError: tried to access method org.apache.lucene.analysis.Tokenizer.(Ljava/io/Reader;)V from class org.apache.lucene.analysis.snowball.SnowballAnalyzer Here is the code, I would very much appreciate help!!!! I am new with this.. public class Indexer { private Indexer(){}; private String[] stopWords = {....}; private String indexName; private IndexWriter iWriter; private static String FILES_TO_INDEX = "/Users/ssi/forindexing"; public static void main(String[] args) throws Exception { Indexer m = new Indexer(); m.index("./newindex"); } public void index(String indexName) throws Exception { this.indexName = indexName; final File docDir = new File(FILES_TO_INDEX); if(!docDir.exists() || !docDir.canRead()){ System.err.println("Something wrong... " + docDir.getPath()); System.exit(1); } Date start = new Date(); PerFieldAnalyzerWrapper analyzers = new PerFieldAnalyzerWrapper(new SimpleAnalyzer()); analyzers.addAnalyzer("text", new SnowballAnalyzer("English", stopWords)); Directory directory = FSDirectory.open(new File(this.indexName)); IndexWriter.MaxFieldLength maxLength = IndexWriter.MaxFieldLength.UNLIMITED; iWriter = new IndexWriter(directory, analyzers, true, maxLength); System.out.println("Indexing to dir..........." + indexName); if(docDir.isDirectory()){ File[] files = docDir.listFiles(); if(files != null){ for (int i = 0; i < files.length; i++) { try { indexDocument(files[i]); }catch (FileNotFoundException fnfe){ fnfe.printStackTrace(); } } } } System.out.println("Optimizing...... "); iWriter.optimize(); iWriter.close(); Date end = new Date(); System.out.println("Time to index was" + (end.getTime()-start.getTime()) + "miliseconds"); } private void indexDocument(File someDoc) throws IOException { Document doc = new Document(); Field name = new Field("name", someDoc.getName(), Field.Store.YES, Field.Index.ANALYZED); Field text = new Field("text", new FileReader(someDoc), Field.TermVector.WITH_POSITIONS_OFFSETS); doc.add(name); doc.add(text); iWriter.addDocument(doc); } }

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  • Parallel For Loop - Problems when adding to a List - Possible .Net Bugs

    - by Kevin Crowell
    I am having some issues involving Parallel for loops and adding to a List. The problem is, the same code may generate different output at different times. I have set up some test code below. In this code, I create a List of 10,000 int values. 1/10th of the values will be 0, 1/10th of the values will be 1, all the way up to 1/10th of the values being 9. After setting up this List, I setup a Parallel for loop that iterates through the list. If the current number is 0, I add a value to a new List. After the Parallel for loop completes, I output the size of the list. The size should always be 1,000. Most of the time, the correct answer is given. However, I have seen 3 possible incorrect outcomes occur: The size of the list is less than 1,000 An IndexOutOfRangeException occurs @ doubleList.Add(0.0); An ArgumentException occurs @ doubleList.Add(0.0); The message for the ArgumentException given was: Destination array was not long enough. Check destIndex and length, and the array's lower bounds. What could be causing the errors? Is this a .Net bug? Is there something I can do to prevent this from happening? Please try the code for yourself. If you do not get an error, try it a few times. Please also note that you probably will not see any errors using a single-core machine. using System; using System.Collections.Generic; using System.Threading.Tasks; namespace ParallelTest { class Program { static void Main(string[] args) { List<int> intList = new List<int>(); List<double> doubleList = new List<double>(); for (int i = 0; i < 250; i++) { intList.Clear(); doubleList.Clear(); for (int j = 0; j < 10000; j++) { intList.Add(j % 10); } Parallel.For(0, intList.Count, j => { if (intList[j] == 0) { doubleList.Add(0.0); } }); if (doubleList.Count != 1000) { Console.WriteLine("On iteration " + i + ": List size = " + doubleList.Count); } } Console.WriteLine("\nPress any key to exit."); Console.ReadKey(); } } }

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  • Unselecting RadioButtons in Java Swing

    - by Thomas
    When displaying a group of JRadioButtons, initially none of them is selected (unless you programmatically enforce that). I would like to be able to put buttons back into that state even after the user already selected one, i.e., none of the buttons should be selected. However, using the usual suspects doesn't deliver the required effect: calling 'setSelected(false)' on each button doesn't work. Interestingly, it does work when the buttons are not put into a ButtonGroup - unfortunately, the latter is required for JRadioButtons to be mutually exclusive. Also, using the setSelected(ButtonModel, boolean) - method of javax.swing.ButtonGroup doesn't do what I want. I've put together a small program to demonstrate the effect: two radio buttons and a JButton. Clicking the JButton should unselect the radio buttons so that the window looks exactly as it does when it first pops up. import java.awt.Container; import java.awt.GridLayout; import java.awt.event.*; import javax.swing.*; /** * This class creates two radio buttons and a JButton. Initially, none * of the radio buttons is selected. Clicking on the JButton should * always return the radio buttons into that initial state, i.e., * should disable both radio buttons. */ public class RadioTest implements ActionListener { /* create two radio buttons and a group */ private JRadioButton button1 = new JRadioButton("button1"); private JRadioButton button2 = new JRadioButton("button2"); private ButtonGroup group = new ButtonGroup(); /* clicking this button should unselect both button1 and button2 */ private JButton unselectRadio = new JButton("Unselect radio buttons."); /* In the constructor, set up the group and event listening */ public RadioTest() { /* put the radio buttons in a group so they become mutually * exclusive -- without this, unselecting actually works! */ group.add(button1); group.add(button2); /* listen to clicks on 'unselectRadio' button */ unselectRadio.addActionListener(this); } /* called when 'unselectRadio' is clicked */ public void actionPerformed(ActionEvent e) { /* variant1: disable both buttons directly. * ...doesn't work */ button1.setSelected(false); button2.setSelected(false); /* variant2: disable the selection via the button group. * ...doesn't work either */ group.setSelected(group.getSelection(), false); } /* Test: create a JFrame which displays the two radio buttons and * the unselect-button */ public static void main(String[] args) { JFrame frame = new JFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); RadioTest test = new RadioTest(); Container contentPane = frame.getContentPane(); contentPane.setLayout(new GridLayout(3,1)); contentPane.add(test.button1); contentPane.add(test.button2); contentPane.add(test.unselectRadio); frame.setSize(400, 400); frame.setVisible(true); } } Any ideas anyone? Thanks!

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  • Time required for a process to complete

    - by yelkawar
    I am new to C# world. I am attempting to calculate time taken by a algorithum for the purpose of comparison. Following code measures the elapsed time from when a subroutine is called until the subroutine returns to the main program.This example is taken from "Data structures through C#" by Michael McMillan. After running this program the output is Time=0, which is incorrect. The program appears to be logically correct. Can anybody help me. Following is the code using System.Collections.Generic; using System.Collections; using System.Linq; using System.Text; namespace Chap1 { class Program { static void Main(string[] args) { int num1 = 100; int num2 = 200; Console.WriteLine("num1: " + num1); Console.WriteLine("num2: " + num2); Swap<int>(ref num1, ref num2); Console.WriteLine("num1: " + num1); Console.WriteLine("num2: " + num2); string str1 = "Sam"; string str2 = "Tom"; Console.WriteLine("String 1: " + str1); Console.WriteLine("String 2: " + str2); Swap<string>(ref str1, ref str2); Console.WriteLine("String 1: " + str1); Console.WriteLine("String 2: " + str2); Console.ReadKey(); } static void Swap<T>(ref T val1, ref T val2) { T temp; temp = val1; val1 = val2; val2 = temp; } } class Timing { TimeSpan StartTiming; TimeSpan duration; public Timing() { StartTiming = new TimeSpan(0); duration = new TimeSpan(0); } public TimeSpan startTime() { GC.Collect(); GC.WaitForPendingFinalizers(); StartTiming = Process.GetCurrentProcess().Threads[0].UserProcessorTime; return StartTiming; } public void stopTime() { duration = Process.GetCurrentProcess().Threads[0].UserProcessorTime.Subtract(StartTiming); } public TimeSpan result() { return duration; } } }

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  • SWIG & Java Use of carrays.i and array_functions for C Array of Strings

    - by c12
    I have the below configuration where I'm trying to create a test C function that returns a pointer to an Array of Strings and then wrap that using SWIG's carrays.i and array_functions so that I can access the Array elements in Java. Uncertainties: %array_functions(char, SWIGArrayUtility); - not sure if char is correct inline char *getCharArray() - not sure if C function signature is correct String result = getCharArray(); - String return seems odd, but that's what is generated by SWIG SWIG.i: %module Test %{ #include "test.h" %} %include <carrays.i> %array_functions(char, SWIGArrayUtility); %include "test.h" %pragma(java) modulecode=%{ public static char[] getCharArrayImpl() { final int num = numFoo(); char ret[] = new char[num]; String result = getCharArray(); for (int i = 0; i < num; ++i) { ret[i] = SWIGArrayUtility_getitem(result, i); } return ret; } %} Inline Header C Function: #ifndef TEST_H #define TEST_H inline static unsigned short numFoo() { return 3; } inline char *getCharArray(){ static char* foo[3]; foo[0]="ABC"; foo[1]="5CDE"; foo[2]="EEE6"; return foo; } #endif Java Main Tester: public class TestMain { public static void main(String[] args) { System.loadLibrary("TestJni"); char[] test = Test.getCharArrayImpl(); System.out.println("length=" + test.length); for(int i=0; i < test.length; i++){ System.out.println(test[i]); } } } Java Main Tester Output: length=3 ? ? , SWIG Generated Java APIs: public class Test { public static String new_SWIGArrayUtility(int nelements) { return TestJNI.new_SWIGArrayUtility(nelements); } public static void delete_SWIGArrayUtility(String ary) { TestJNI.delete_SWIGArrayUtility(ary); } public static char SWIGArrayUtility_getitem(String ary, int index) { return TestJNI.SWIGArrayUtility_getitem(ary, index); } public static void SWIGArrayUtility_setitem(String ary, int index, char value) { TestJNI.SWIGArrayUtility_setitem(ary, index, value); } public static int numFoo() { return TestJNI.numFoo(); } public static String getCharArray() { return TestJNI.getCharArray(); } public static char[] getCharArrayImpl() { final int num = numFoo(); char ret[] = new char[num]; String result = getCharArray(); System.out.println("result=" + result); for (int i = 0; i < num; ++i) { ret[i] = SWIGArrayUtility_getitem(result, i); System.out.println("ret[" + i + "]=" + ret[i]); } return ret; } }

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  • What's a clean way to break up a DataTable into chunks of a fixed size with Linq?

    - by Michael Haren
    Update: Here's a similar question Suppose I have a DataTable with a few thousand DataRows in it. I'd like to break up the table into chunks of smaller rows for processing. I thought C#3's improved ability to work with data might help. This is the skeleton I have so far: DataTable Table = GetTonsOfData(); // Chunks should be any IEnumerable<Chunk> type var Chunks = ChunkifyTableIntoSmallerChunksSomehow; // ** help here! ** foreach(var Chunk in Chunks) { // Chunk should be any IEnumerable<DataRow> type ProcessChunk(Chunk); } Any suggestions on what should replace ChunkifyTableIntoSmallerChunksSomehow? I'm really interested in how someone would do this with access C#3 tools. If attempting to apply these tools is inappropriate, please explain! Update 3 (revised chunking as I really want tables, not ienumerables; going with an extension method--thanks Jacob): Final implementation: Extension method to handle the chunking: public static class HarenExtensions { public static IEnumerable<DataTable> Chunkify(this DataTable table, int chunkSize) { for (int i = 0; i < table.Rows.Count; i += chunkSize) { DataTable Chunk = table.Clone(); foreach (DataRow Row in table.Select().Skip(i).Take(chunkSize)) { Chunk.ImportRow(Row); } yield return Chunk; } } } Example consumer of that extension method, with sample output from an ad hoc test: class Program { static void Main(string[] args) { DataTable Table = GetTonsOfData(); foreach (DataTable Chunk in Table.Chunkify(100)) { Console.WriteLine("{0} - {1}", Chunk.Rows[0][0], Chunk.Rows[Chunk.Rows.Count - 1][0]); } Console.ReadLine(); } static DataTable GetTonsOfData() { DataTable Table = new DataTable(); Table.Columns.Add(new DataColumn()); for (int i = 0; i < 1000; i++) { DataRow Row = Table.NewRow(); Row[0] = i; Table.Rows.Add(Row); } return Table; } }

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  • What Regex can strip e.g. "note:" and "firstName: " from the left of a string?

    - by Edward Tanguay
    I need to strip the "label" off the front of strings, e.g. note: this is a note needs to return: note and this is a note I've produced the following code example but am having trouble with the regexes. What code do I need in the two ???????? areas below so that I get the desired results shown in the comments? using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Text.RegularExpressions; namespace TestRegex8822 { class Program { static void Main(string[] args) { List<string> lines = new List<string>(); lines.Add("note: this is a note"); lines.Add("test: just a test"); lines.Add("test:\t\t\tjust a test"); lines.Add("firstName: Jim"); //"firstName" IS a label because it does NOT contain a space lines.Add("She said this to him: follow me."); //this is NOT a label since there is a space before the colon lines.Add("description: this is the first description"); lines.Add("description:this is the second description"); //no space after colon lines.Add("this is a line with no label"); foreach (var line in lines) { Console.WriteLine(StringHelpers.GetLabelFromLine(line)); Console.WriteLine(StringHelpers.StripLabelFromLine(line)); Console.WriteLine("--"); //note //this is a note //-- //test //just a test //-- //test //just a test //-- //firstName //Jim //-- // //She said this to him: follow me. //-- //description //this is the first description //-- //description //this is the first description //-- // //this is a line with no label //-- } Console.ReadLine(); } } public static class StringHelpers { public static string GetLabelFromLine(this string line) { string label = line.GetMatch(@"^?:(\s)"); //??????????????? if (!label.IsNullOrEmpty()) return label; else return ""; } public static string StripLabelFromLine(this string line) { return ...//??????????????? } public static bool IsNullOrEmpty(this string line) { return String.IsNullOrEmpty(line); } } public static class RegexHelpers { public static string GetMatch(this string text, string regex) { Match match = Regex.Match(text, regex); if (match.Success) { string theMatch = match.Groups[0].Value; return theMatch; } else { return null; } } } }

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  • java timer on current instance

    - by hspim
    import java.util.Scanner; import java.util.Timer; import java.util.TimerTask; public class Boggle { Board board; Player player; Timer timer; boolean active; static Scanner in = new Scanner(System.in); public Boggle() { board = new Board(4); timer = new Timer(); } public void newGame() { System.out.println("Please enter your name: "); String line = in.nextLine(); player = new Player(line); active = true; board.shuffle(); System.out.println(board); timer.schedule(new timesUP(), 20000); while(active) { String temp = in.nextLine(); player.addGuess(temp); } } public void endGame() { active = false; int score = Scoring.calculate(player, board); System.out.println(score); } class timesUP extends TimerTask { public void run() { endGame(); } } public static void main(String[] args) { Boggle boggle = new Boggle(); boggle.newGame(); } } I have the above class which should perform a loop for a given length of time and afterwards invoke an instance method. Essentially I need the loop in newGame() to run for a minute or so before endGame() is invoked on the current instance. However, using the Timer class I'm not sure how I would invoke the method I need on the current instance since I can't pass any parameters to the timertasks run method? Is there an easy way to do this or am I going about this the wrong way? (note: this is a console project only, no GUI) ========== code edited I've changed the code to the above following the recommendations, and it works almost as I expect however the thread still doesnt seem to end properly. I was the while loop would die and control would eventually come back to the main method. Any ideas?

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  • How to implement code for multiple buttons using c++ in Silverlight for Windows Embedded

    - by Abhi
    Dear all I have referred the following link: Silverlight for Windows Embedded By referring this link i created a demo application which consist of two buttons created using Microsoft expression blend 2 tools. And then written a code referring the above site. Now my button names are "Browser Button" and "Media Button". On click of any one of the button i should able to launch the respective application. I was able to do for "Browser Button" but not for "Media Button" and if i do for "Media Button" then i am not able to do for "Browser Button".. I mean to say that how should i create event handler for both the buttons. This is the code in c++ which i should modify class BtnEventHandler { public: HRESULT OnClick(IXRDependencyObject* source,XRMouseButtonEventArgs* args) { RETAILMSG(1,(L"Browser event")); Execute(L"\\Windows\\iesample.exe",L""); return S_OK; } }; // entry point for the application. INT WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance, LPWSTR lpCmdLine,int nCmdShow) { PrintMessage(); int exitCode = -1; HRESULT hr = S_OK; if (!XamlRuntimeInitialize()) return -1; HRESULT retcode; IXRApplicationPtr app; if (FAILED(retcode=GetXRApplicationInstance(&app))) return -1; if (FAILED(retcode=app->AddResourceModule(hInstance))) return -1; XRWindowCreateParams wp; ZeroMemory(&wp, sizeof(XRWindowCreateParams)); wp.Style = WS_OVERLAPPED; wp.pTitle = L"Bounce Test"; wp.Left = 0; wp.Top = 0; XRXamlSource xamlsrc; xamlsrc.SetResource(hInstance,TEXT("XAML"),MAKEINTRESOURCE(IDR_XAML1)); IXRVisualHostPtr vhost; if (FAILED(retcode=app->CreateHostFromXaml(&xamlsrc, &wp, &vhost))) return -1; IXRFrameworkElementPtr root; if (FAILED(retcode=vhost->GetRootElement(&root))) return -1; IXRButtonBasePtr btn; if (FAILED(retcode=root->FindName(TEXT("BrowserButton"), &btn))) return -1; IXRDelegate<XRMouseButtonEventArgs>* clickdelegate; BtnEventHandler handler; if(FAILED(retcode=CreateDelegate (&handler,&BtnEventHandler::OnClick,&clickdelegate))) return -1; if (FAILED(retcode=btn->AddClickEventHandler(clickdelegate))) return -1; UINT exitcode; if (FAILED(retcode=vhost->StartDialog(&exitcode))) return -1; return exitCode; } I have to add event handler for both the button so that on emulator whenever i click on any one of the button i should be able to launch the respective applications. Thanks in advance

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  • Saving image to database as varbinary, arraylength (part 2)

    - by Thomas Schoof
    This is a followup to my previous question, which got solved (thank you for that) but now I am stuck at another error. I'm trying to save an image in my database (called 'Afbeelding'), for that I made a table which excists of: id: int souce: varbinary(max) I then created a wcf service to save an 'Afbeelding' to the database. private static DataClassesDataContext dc = new DataClassesDataContext(); [OperationContract] public void setAfbeelding(Afbeelding a) { //Afbeelding a = new Afbeelding(); //a.id = 1; //a.source = new Binary(bytes); dc.Afbeeldings.InsertOnSubmit(a); dc.SubmitChanges(); } I then put a reference to the service in my project and when I press the button I try to save it to the datbase. private void btnUpload_Click(object sender, RoutedEventArgs e) { Afbeelding a = new Afbeelding(); OpenFileDialog openFileDialog = new OpenFileDialog(); openFileDialog.Filter = "JPEG files|*.jpg"; if (openFileDialog.ShowDialog() == true) { //string imagePath = openFileDialog.File.Name; //FileStream fileStream = new FileStream(imagePath, FileMode.Open, FileAccess.Read); //byte[] buffer = new byte[fileStream.Length]; //fileStream.Read(buffer, 0, (int)fileStream.Length); //fileStream.Close(); Stream stream = (Stream)openFileDialog.File.OpenRead(); Byte[] bytes = new Byte[stream.Length]; stream.Read(bytes, 0, (int)stream.Length); string fileName = openFileDialog.File.Name; a.id = 1; a.source = new Binary { Bytes = bytes }; } EditAfbeeldingServiceClient client = new EditAfbeeldingServiceClient(); client.setAfbeeldingCompleted +=new EventHandler<System.ComponentModel.AsyncCompletedEventArgs>(client_setAfbeeldingCompleted); client.setAfbeeldingAsync(a); } void client_setAfbeeldingCompleted(object sender, System.ComponentModel.AsyncCompletedEventArgs e) { if (e.Error != null) txtEmail.Text = e.Error.ToString(); else MessageBox.Show("WIN"); } However, when I do this, I get the following error: System.ServiceModel.FaultException: The formatter threw an exception while trying to deserialize the message: There was an error while trying to deserialize parameter :a. The InnerException message was 'There was an error deserializing the object of type OndernemersAward.Web.Afbeelding. The maximum array length quota (16384) has been exceeded while reading XML data. This quota may be increased by changing the MaxArrayLength property on the XmlDictionaryReaderQuotas object used when creating the XML reader.'. Please see InnerException for more details. at System.ServiceModel.Channels.ServiceChannel.HandleReply(ProxyOperationRuntime operation, ProxyRpc& rpc) at System.ServiceModel.Channels.ServiceChannel.EndCall(String action, Object[] outs, IAsyncResult result) at System.ServiceModel.ClientBase`1.ChannelBase`1.EndInvoke(String methodName, Object[] args, IAsyncResult result) atOndernemersAward.EditAfbeeldingServiceReference.EditAfbeeldingServiceClient.EditAfbeeldingServiceClientChannel.EndsetAfbeelding(IAsyncResult result) at OndernemersAward.EditAfbeeldingServiceReference.EditAfbeeldingServiceClient.OndernemersAward.EditAfbeeldingServiceReference.EditAfbeeldingService.EndsetAfbeelding(IAsyncResult result) at OndernemersAward.EditAfbeeldingServiceReference.EditAfbeeldingServiceClient.OnEndsetAfbeelding(IAsyncResult result) at System.ServiceModel.ClientBase`1.OnAsyncCallCompleted(IAsyncResult result) I'm not sure what's causing this but I think it has something to do with the way I write the image to the database? (The array length is too big big, I don't really know how to change it) Thank you for your help, Thomas

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  • Problem to focus JTextField

    - by Tom Brito
    I have used the approach of the ComponentListener to call focus in JTextField within a dialog, but for this case is just not working, I don't know why. It shows the focus in the text field and fast change to the button. Run and see: import java.awt.Component; import java.awt.GridLayout; import java.awt.event.ComponentEvent; import java.awt.event.ComponentListener; import javax.swing.JDialog; import javax.swing.JLabel; import javax.swing.JOptionPane; import javax.swing.JPanel; import javax.swing.JPasswordField; import javax.swing.JTextField; public class User { private String username = ""; private String password = ""; public User() { // default constructor } public User(String username, String password) { this.username = username; this.password = password; } /** Create a panel containing the componet and tha label. */ public JPanel createLabeledComponent(JLabel label, Component comp) { GridLayout layout = new GridLayout(2, 1); JPanel panel = new JPanel(layout); panel.add(label); panel.add(comp); label.setLabelFor(comp); return panel; } public void showEditDialog() { JLabel usernameLbl = new JLabel(username); final JTextField usernameField = new JTextField(); usernameField.setText(username); JPanel usernamePnl = createLabeledComponent(usernameLbl, usernameField); JLabel passwordLbl = new JLabel(password); JPasswordField passwordField = new JPasswordField(password); JPanel passwordPnl = createLabeledComponent(passwordLbl, passwordField); Object[] fields = { "User:", usernamePnl, "Password:", passwordPnl }; JOptionPane optionPane = new JOptionPane(fields, JOptionPane.PLAIN_MESSAGE, JOptionPane.OK_CANCEL_OPTION, null, null); JDialog dialog = optionPane.createDialog("User Data"); dialog.addComponentListener(new ComponentListener() { public void componentShown(ComponentEvent e) { usernameField.requestFocusInWindow(); } public void componentResized(ComponentEvent e) {} public void componentMoved(ComponentEvent e) {} public void componentHidden(ComponentEvent e) {} }); dialog.setVisible(true); } public static void main(String[] args) { new User().showEditDialog(); } } Any idea how to solve this?

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  • log4net initialisation

    - by Ruben Bartelink
    I've looked hard for duplicates but have to ask the following, no matter how basic it may seem, to get it clear once and for all! In a fresh Console app using log4net version 1.2.10.0 on VS28KSP1 on 64 bit W7, I have the following code:- using log4net; using log4net.Config; namespace ConsoleApplication1 { class Program { static readonly ILog _log = LogManager.GetLogger(typeof(Program)); static void Main(string[] args) { _log.Info("Ran"); } } } In my app.config, I have: <?xml version="1.0" encoding="utf-8" ?> <configuration> <configSections> <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" /> </configSections> <log4net> <appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender"> <file value="Program.log" /> <lockingModel type="log4net.Appender.FileAppender+MinimalLock" /> <appendToFile value="true" /> <rollingStyle value="Size" /> <maxSizeRollBackups value="10" /> <maximumFileSize value="1MB" /> <staticLogFileName value="true" /> <layout type="log4net.Layout.PatternLayout"> <conversionPattern value="[%username] %date [%thread] %-5level %logger [%property{NDC}] - %message%newline" /> </layout> </appender> <root> <level value="DEBUG" /> <appender-ref ref="RollingFileAppender" /> </root> </log4net> </configuration> This doesnt write anything, unless I either add an attribute: [ assembly:XmlConfigurator ] Or explicitly initialise it in Main(): _log.Info("This will not go to the log"); XmlConfigurator.Configure(); _log.Info("Ran"); This raises the following questions: I'm almost certain I've seen it working somewhere on some version of log4net without the addition of the assembly attribute or call in Main. Can someone assure me I'm not imagining that? Can someone please point me to where in the doc it explicitly states that both the config section and the initialisation hook are required - hopefully with an explanation of when this changed, if it did? I can easily imagine why this might be the policy -- having the initialisation step explicit to avoid surprises etc., it's just that I seem to recall this not always being the case... (And normally I have the config in a separate file, which generally takes configsections out of the picture)

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  • C++ vs. C++/CLI: Const qualification of virtual function parameters

    - by James McNellis
    [All of the following was tested using Visual Studio 2008 SP1] In C++, const qualification of parameter types does not affect the type of a function (8.3.5/3: "Any cv-qualifier modifying a parameter type is deleted") So, for example, in the following class hierarchy, Derived::Foo overrides Base::Foo: struct Base { virtual void Foo(const int i) { } }; struct Derived : Base { virtual void Foo(int i) { } }; Consider a similar hierarchy in C++/CLI: ref class Base abstract { public: virtual void Foo(const int) = 0; }; ref class Derived : public Base { public: virtual void Foo(int i) override { } }; If I then create an instance of Derived: int main(array<System::String ^> ^args) { Derived^ d = gcnew Derived; } it compiles without errors or warnings. When I run it, it throws the following exception and then terminates: An unhandled exception of type 'System.TypeLoadException' occurred in ClrVirtualTest.exe Additional information: Method 'Foo' in type 'Derived'...does not have an implementation. That exception seems to indicate that the const qualification of the parameter does affect the type of the function in C++/CLI (or, at least it affects overriding in some way). However, if I comment out the line containing the definition of Derived::Foo, the compiler reports the following error (on the line in main where the instance of Derived is instantiated): error C2259: 'Derived': cannot instantiate abstract class If I add the const qualifier to the parameter of Derived::Foo or remove the const qualifier from the parameter of Base::Foo, it compiles and runs with no errors. I would think that if the const qualification of the parameter affects the type of the function, I should get this error if the const qualification of the parameter in the derived class virtual function does not match the const qualification of the parameter in the base class virtual function. If I change the type of Derived::Foo's parameter from an int to a double, I get the following warning (in addition to the aforementioned error, C2259): warning C4490: 'override': incorrect use of override specifier; 'Derived::Foo' does not match a base ref class method So, my question is, effectively, does the const qualification of function parameters affect the type of the function in C++/CLI? If so, why does this compile and why are there no errors or warnings? If not, why is an exception thrown?

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  • Connect to SQLite Database using Eclipse (Java)

    - by bnabilos
    Hello, I'm trying to connect to SQLite database with Ecplise but I have some errors. This is my Java code and the errors that I get on output. Please see if you can help me. Thank you in advance. package jdb; import java.sql.*; public class Test { public static void main(String[] args) throws Exception { Class.forName("org.sqlite.JDBC"); Connection conn = DriverManager.getConnection("jdbc:sqlite:/Applications/MAMP/db/sqlite/test.sqlite"); Statement stat = conn.createStatement(); stat.executeUpdate("drop table if exists people;"); stat.executeUpdate("create table people (name, occupation);"); PreparedStatement prep = conn.prepareStatement( "insert into people values (?, ?);"); prep.setString(1, "Gandhi"); prep.setString(2, "politics"); prep.addBatch(); prep.setString(1, "Turing"); prep.setString(2, "computers"); prep.addBatch(); prep.setString(1, "Wittgenstein"); prep.setString(2, "smartypants"); prep.addBatch(); conn.setAutoCommit(false); prep.executeBatch(); conn.setAutoCommit(true); ResultSet rs = stat.executeQuery("select * from people;"); while (rs.next()) { System.out.println("name = " + rs.getString("name")); System.out.println("job = " + rs.getString("occupation")); } rs.close(); conn.close(); } } ans that what I get in Ecplise : Exception in thread "main" java.lang.ClassNotFoundException: org.sqlite.JDBC at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at java.lang.ClassLoader.loadClass(ClassLoader.java:315) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:330) at java.lang.ClassLoader.loadClass(ClassLoader.java:250) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:398) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:169) at jdb.Test.main(Test.java:7) Thank you

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