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  • What are possible reasons for java.io.IOException: "The filename, directory name, or volume label sy

    - by Turismo
    I am trying to copy a file using the following code: File targetFile = new File(targetPath + File.separator + filename); ... targetFile.createNewFile(); fileInputStream = new FileInputStream(fileToCopy); fileOutputStream = new FileOutputStream(targetFile); byte[] buffer = new byte[64*1024]; int i = 0; while((i = fileInputStream.read(buffer)) != -1) { fileOutputStream.write(buffer, 0, i); } For some users the targetFile.createNewFile results in this exception: java.io.IOException: The filename, directory name, or volume label syntax is incorrect at java.io.WinNTFileSystem.createFileExclusively(Native Method) at java.io.File.createNewFile(File.java:850) Filename and directory name seem to be correct. The directory targetPath is even checked for existence before the copy code is executed and the filename looks like this: AB_timestamp.xml The user has write permissions to the targetPath and can copy the file without problems using the OS. As I don't have access to a machine this happens on yet and can't reproduce the problem on my own machine I turn to you for hints on the reason for this exception.

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  • Matrix multiplication in java (RE-POST)

    - by Chapax
    Apologies for the re-post; the earlier time I'd posted I did not have all the details. My colleague, who quit the firm was a C# programmer, was forced to write Java code that involved (large, dense) matrix multiplication. He's coded his own DataTable class in Java, in order to be able to a) create indexes to sort and join with other DataTables b) do matrix multiplication. The code in its current form is NOT maintainable/extensible. I want to clean up the code, and thought using something like R within Java will help me focus on business logic rather than sorting, joining, matrix multiplication, etc. Plus, I'm very new to the concept of DataTable; I just want to replace the DataTable with 2D arrays, and let R handle the rest. (I currently do not know how to join 2 large datasets in java very efficiently Please let me know what you think. Also, are there any simple examples that I can take a look at?

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  • Setting minimum size limit for a window in java swing

    - by shadyabhi
    I have a JFrame which has 3 JPanels in GridBagLayout.. Now, when I minimize a windows, after a certain limit, the third JPanel tends to disappear. I tried setting minimizing size of JFrame using setMinimumSize(new Dimension(int,int)) but no success. The windows can still be minimized. So, I actually want to make a threshhold, that my window cannot be minimized after a certain limit. How can I do so? Code:- import java.awt.Dimension; import javax.swing.JFrame; public class JFrameExample { public static void main(String[] args) { JFrame frame = new JFrame("Hello World"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setMinimumSize(new Dimension(400, 400)); frame.setVisible(true); } } Also: shadyabhi@shadyabhi-desktop:~/java$ java --showversion java version "1.5.0" gij (GNU libgcj) version 4.4.1 Copyright (C) 2007 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Usage: gij [OPTION] ... CLASS [ARGS] ... to invoke CLASS.main, or gij -jar [OPTION] ... JARFILE [ARGS] ... to execute a jar file Try `gij --help' for more information. shadyabhi@shadyabhi-desktop:~/java$ Gives me output like

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  • Generating ActionScript value objects from middle-tier Java classes

    - by eli
    In a Flex / Java app stack using remoting (via BlazeDS), classes to hold data passed back and forth between client and server need to be maintained in both the client (in ActionScript) and server (in Java). I want a way to maintain theses classes in Java only, and have the corresponding ActionScript value object classes generated by the build process.

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  • Java MouseEvents not working

    - by billynomates
    This may be a stupid question, but I have to ask! I have the following code snippets that are supposed to run their corresponding methods when the user interacts with objects. For some reason, "foo" is never printed, but "bar" is. myJSpinner1.addMouseListener(new java.awt.event.MouseAdapter() { public void mouseEntered(java.awt.event.MouseEvent evt() { System.out.println("foo"); //"foo" is not printed } }); myJSpinner2.addChangeListener(new java.awt.event.ChangeListener() { public void stateChanged(java.awt.event.ChangeEvent evt() { System.out.println("bar"); //"bar" is printed } }); I get no exceptions or stack trace. What am I missing in the MouseListener one? Thanks in advance.

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  • Modbus driver: C vs Java

    - by cpf
    Hi stackoverflow, I am soon going to start a project where I'm required to program a Modbus driver. My initial approach was to want to do it in Java, however my boss has had contact with a company that has experience in Modbus, and they said C is the better language to approach Modbus. So my boss pretty much demanded it to be in C. My C knowledge is not really big, so it would require me to learn enough to get the Modbus driver working in proper and stable order. So, my question to you stackoverflow people with some experience in Modbus: how important could the choice of C vs Java be? The modbus site seems to have Java libraries, if C was so superior to Java in every way, why would they have those libraries? Would it be useful to learn C properly for the advantages that might give?

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  • Memory-Mapped Files & Transparent Persistence of Java Objects

    - by geeko
    Greeting All, I want to achieve transparent persistence of Java objects through memory-mapped files (utilize the OS paging/swapping mechanism). My problem is: how can I move a Java object to my memory-mapped block ? Plus, how can I force a new object instance to reside in such blocks ? As you all know, a memory-mapped block can be seen as a byte array, and what I am really asking here is how to overlap the address space of Java objects with the one of such arrays ? If Java does not allow me for this, what cross-platform & garbage-collecting OO language would you advise me to use ? Thank you all in advance.

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  • How can I write System preferences with Java? Can I invoke UAC?

    - by Jonas
    How can I write system preferences with Java, using Preferences.systemRoot()? I tried with: Preferences preferences = Preferences.systemRoot(); preferences.put("/myapplication/databasepath", pathToDatabase); But I got this error message: 2010-maj-29 19:02:50 java.util.prefs.WindowsPreferences openKey VARNING: Could not open windows registry node Software\JavaSoft\Prefs at root 0x80000002. Windows RegOpenKey(...) returned error code 5. Exception in thread "AWT-EventQueue-0" java.lang.SecurityException: Could not open windows registry node Software\JavaSoft\Prefs at root 0x80000002: Access denied at java.util.prefs.WindowsPreferences.openKey(Unknown Source) at java.util.prefs.WindowsPreferences.openKey(Unknown Source) at java.util.prefs.WindowsPreferences.openKey(Unknown Source) at java.util.prefs.WindowsPreferences.putSpi(Unknown Source) at java.util.prefs.AbstractPreferences.put(Unknown Source) at biz.accountia.pos.install.Setup$2.actionPerformed(Setup.java:43) I would like to do this, because I want to install an embedded JavaDB database, and let multiple users on the computer to use the same database with the application. How to solve this? Can I invoke UAC and do this as Administrator from Java? And if I log in as Administrator when writing, can I read the values with my Java application if I'm logged in as a User?

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  • Java Socket fails to transmit data over the network

    - by Mark Griffin
    I'm experiencing a bizarre problem with sockets between a Java Knopflerfish client bundle and a PHP (CLI, not web) server. The client/server pair work fine when both are located on the localhost, and all data is transmitted successfully. However, when the Java client exists on a different machine, connections to the server are successful, but no data is received by the PHP script. Packet analysis confirms that the data sent by the Java client is received on by the server - PHP just seems to have problems getting its hands on it. As a further note, I've done some tests with telnet as the client. The PHP server script receives all data fine from any host. This leads me to believe that the problem has something to do with the way java is setting up the socket or that there is some networking issue that I'm not familiar with. Any thoughts would be appreciated. Can post code samples if desired.

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  • Embedding Lua functions as member variables in Java

    - by Zarion
    Although the program I'm working on is in Java, answering this from a C perspective is also fine, considering that most of this is either language-agnostic, or happens on the Lua side of things. In the outline I have for the architecture of a game I'm programming, individual types of game objects within a particular class (eg: creatures, items, spells, etc.) are loaded from a data file. Most of their properties are simple data types, but I'd like a few of these members to actually contain simple scripts that define, for example, what an item does when it's used. The scripts will be extremely simple, since all fundamental game actions will be exposed through an API from Java. The Lua is simply responsible for stringing a couple of these basic functions together, and setting arguments. The question is largely about the best way to store a reference to a specific Lua function as a member of a Java class. I understand that if I store the Lua code as a string and call lua_dostring, Lua will compile the code fresh every time it's called. So the function needs to be defined somehow, and a reference to this specific function wrapped in a Java function object. One possibility that I've considered is, during the data loading process, when the loader encounters a script definition in a data file, it extracts this string, decorates the function name using the associated object's unique ID, calls lua_dostring on the string containing a full function definition, and then wraps the generated function name in a Java function object. A function declared in script run with lua_dostring should still be added to the global function table, correct? I'm just wondering if there's a better way of going about this. I admit that my knowledge of Lua at this point is rather superficial and theoretical, so it's possible that I'm overlooking something obvious.

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  • java - codesprint2 programming contest answer

    - by arya
    I recently took part in Codesprint2. I was unable to submit the solution to the following question. http://www.spoj.pl/problems/COINTOSS/ ( I have posted the link to the problem statement at spoj because the codesprint link requires login ) I checked out one of the successful solutions, ( url : http://pastebin.com/uQhNh9Rc ) and the logic used is exactly the same as mine, yet I am still getting "Wrong Answer" I would be very thankful if someone could please tell me what error I have made, as I am unable to find it. Thank you. My code : import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.text.DecimalFormat; import java.util.StringTokenizer; public class Solution { static double solve( int n, int m ) { if( m==n ) return 0; if( m==0 ) return ( Math.pow( 2, n+1 ) - 2 ); else { double res = 1 + ( Double )( solve( n, m+1 ) + solve( n, 0 ))/2; return res; } } public static void main( String[] args ) throws IOException { BufferedReader br = new BufferedReader( new InputStreamReader( System.in )); int n, m; int t = Integer.parseInt( br.readLine() ); StringTokenizer tok; String s; for( int T=0; T<t; T++ ) { s = br.readLine(); tok = new StringTokenizer( s ); n = Integer.parseInt( tok.nextToken() ); m = Integer.parseInt( tok.nextToken() ); DecimalFormat df = new DecimalFormat(); df.setMaximumFractionDigits(2); df.setMinimumFractionDigits(2); System.out.println( df.format ( solve( n, m ) )); } } }

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  • Removing file locks in Windows and Java

    - by Jack
    I have a Java program that opens a file using the RandomAccessFile class. I'd like to be able to rename that file while it is opened by Java. In Unix, this isn't a problem. Does anyone know how I can do this in Windows? Should I set Java to open it a certain way? Thanks in advance.

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  • Available Coroutine Libraries in Java

    - by JUST MY correct OPINION
    I would like to do some stuff in Java that would be clearer if written using concurrent routines, but for which full-on threads are serious overkill. The answer, of course, is the use of coroutines, but there doesn't appear to be any coroutine support in the standard Java libraries and a quick Google on it brings up tantalising hints here or there, but nothing substantial. Here's what I've found so far: JSIM has a coroutine class, but it looks pretty heavyweight and conflates, seemingly, with threads at points. The point of this is to reduce the complexity of full-on threading, not to add to it. Further I'm not sure that the class can be extracted from the library and used independently. Xalan has a coroutine set class that does coroutine-like stuff, but again it's dubious if this can be meaningfully extracted from the overall library. It also looks like it's implemented as a tightly-controlled form of thread pool, not as actual coroutines. There's a Google Code project which looks like what I'm after, but if anything it looks more heavyweight than using threads would be. I'm basically nervous of something that requires software to dynamically change the JVM bytecode at runtime to do its work. This looks like overkill and like something that will cause more problems than coroutines would solve. Further it looks like it doesn't implement the whole coroutine concept. By my glance-over it gives a yield feature that just returns to the invoker. Proper coroutines allow yields to transfer control to any known coroutine directly. Basically this library, heavyweight and scary as it is, only gives you support for iterators, not fully-general coroutines. The promisingly-named Coroutine for Java fails because it's a platform-specific (obviously using JNI) solution. And that's about all I've found. I know about the native JVM support for coroutines in the Da Vinci Machine and I also know about the JNI continuations trick for doing this. These are not really good solutions for me, however, as I would not necessarily have control over which VM or platform my code would run on. (Indeed any bytecode manipulation system would suffer similar problems -- it would be best were this pure Java if possible. Runtime bytecode manipulation would restrict me from using this on Android, for example.) So does anybody have any pointers? Is this even possible? If not, will it be possible in Java 7? Edited to add: Just to ensure that confusion is contained, this is a related question to my other one, but not the same. This one is looking for an existing implementation in a bid to avoid reinventing the wheel unnecessarily. The other one is a question relating to how one would go about implementing coroutines in Java should this question prove unanswerable. The intent is to keep different questions on different threads.

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  • How to specify character encoding for Ant Task parameters in Java

    - by räph
    I'm writing an ANT task in Java. In my build.xml I specify parameters, which should be read from my java class. Problems occur, when I use special characters, like german umlauts (Ö,Ä,Ü) in these parameters. In my java task they appear as ?-characters (using System.out.print). All my files are encoded as UTF-8. and my build.xml has the corresponding declaration: <?xml version="1.0" encoding="UTF-8" ?> For the details of writing the task: I do it according to http://ant.apache.org/manual/develop.html (especially Point 5 nested elements). I have nested elements in my task like: <parameter name="test" value="ÖÄÜtest"/> and a java method: public void addConfiguredParameter(Parameter prop) { System.out.println(prop.getValue()); //prints ???test } to read the parameter values.

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  • Java based Atom/RSS Library that works in Google App Engine

    - by Littlejon
    I am trying to publish an Atom/RSS feed in my Java based Google App Engine code. I have tried using Rome and keep getting the following error (tried googling without success), also the code I am running that generates the error is the demo code (so I get the feeling Rome won't work with GAE) java.lang.NoClassDefFoundError: org/jdom/JDOMException at com.sun.syndication.io.SyndFeedOutput.<init>(SyndFeedOutput.java:44) What I am looking for is recommendations for a simple Java library to create and publish an Atom feed from within Google App Engine. Thanks.

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  • How does Java handle multithreading?

    - by badcodenotreat
    How does Java decide which core to assign a thread or a process? Is there any way to control that? to prevent two large threads from executing on the same core? Basically what I am asking is for further information on either how multi-threading works in Java, or how to control it within Java.

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  • Newb Question: passing objects in java?

    - by Adam Outler
    Hello, I am new at java. I am doing the following: Read from file, then put data into a variable. checkToken = lineToken.nextToken(); processlinetoken() } But then when I try to process it... public static void readFile(String fromFile) throws IOException { BufferedReader reader = new BufferedReader(new FileReader(fromFile)); String line = null; while ((line=reader.readLine()) != null ) { if (line.length() >= 2) { StringTokenizer lineToken = new StringTokenizer (line); checkToken = lineToken.nextToken(); processlinetoken() ...... But here's where I come into a problem. public static void processlinetoken() checkToken=lineToken.nextToken(); } it fails out. Exception in thread "main" java.lang.Error: Unresolved compilation problem: The method nextToken() is undefined for the type String at testread.getEngineLoad(testread.java:243) at testread.readFile(testread.java:149) at testread.main(testread.java:119) so how do I get this to work? It seems to pass the variable, but nothing after the . works.

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  • Problem when getting pageContent of an unavailable URL in Java

    - by tiendv
    I have a code for get pagecontent from a URL: import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.net.URL; import java.net.URLConnection; public class GetPageFromURLAction extends Thread { public String stringPageContent; public String targerURL; public String getPageContent(String targetURL) throws IOException { String returnString=""; URL urlString = new URL(targetURL); URLConnection openConnection = urlString.openConnection(); String temp; BufferedReader in = new BufferedReader( newInputStreamReader(openConnection.getInputStream())); while ((temp = in.readLine()) != null) { returnString += temp + "\n"; } in.close(); // String nohtml = sb.toString().replaceAll("\\<.*?>",""); return returnString; } public String getStringPageContent() { return stringPageContent; } public void setStringPageContent(String stringPageContent) { this.stringPageContent = stringPageContent; } public String getTargerURL() { return targerURL; } public void setTargerURL(String targerURL) { this.targerURL = targerURL; } @Override public void run() { try { this.stringPageContent=this.getPageContent(targerURL); } catch (IOException e) { e.printStackTrace(); } } } Sometimes I receive an HTTP error of 405 or 403 and result string is null. I have tried checking permission to connect to the URL with: URLConnection openConnection = urlString.openConnection(); openConnection.getPermission() but it usualy returns null. Does mean that i don't have permission to access the link? I have tried stripping off the query portion of the URL with: String nohtml = sb.toString().replaceAll("\\<.*?>",""); where sb is a Stringbulder, but it doesn't seem to strip off the whole query substring. In an unrelated question, I'd like to use threads here because I must retrieve many URLs; how can I create a multi-thread client to improve the speed?

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  • How to use my trackpad for horizontal mousewheel scrolling in a Java AWT ScrollPane

    - by blissapp
    Like many modern mice and trackpads, my laptop supports vertical and horizontal scrolling. It's an addictive feature once you get used to it. I simply want my Java apps to support horizontal scrolling via the trackpad/mousewheel, but everywhere I search it seems that this is not possible in Java. I really want someone to tell me that I'm somehow doing it wrong, this feature is already requested behaviour: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6440198 The inability to do this simple thing is actually a deal breaker for the app I'm working on. In fact, for any app I can envision! I've invested a bit of time in the Java backend, so I'd really like to find a solution for this seemingly simple thing. Question is what could I do to implement this behaviour? Are raw OS level events even exposed to java, would I then need to write this from scratch? import java.awt.*; public class ScrollExample extends Canvas { public void paint(Graphics g) { g.setColor(Color.green); g.fillOval(0,0,400, 400); } public static void main(String[] args) { ScrollExample b = new ScrollExample(); Frame f = new Frame ("Scroll Example"); ScrollPane scroller = new ScrollPane (ScrollPane.SCROLLBARS_ALWAYS); scroller.add(b,"Center"); f.setPreferredSize(new Dimension(500,500)); f.add ("Center",scroller); f.pack(); f.show(); } }

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  • Call Ruby class over java with jruby

    - by r2
    Hi all If I implement a class in ruby and compile it with jrubyc than it is not possible to call it from a java class directly if I start it with java. If I see this right I have to use org.jruby.embed... to implement a wrapper wich takes a class name and a metod to call my ruby class. Do I have to do this also if I start the application with jruby? In my current project I start java workflow engine completely with jruby. The workflow has to call a method in a ruby class which he cant find. Maybe easier to understand: [ruby_class] <-----has to call----. | jruby [ruby_start_script] --starts--> [java wfe]

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