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  • Java: ListA.addAll(ListB) fires NullPointerException?

    - by HH
    The err part is Capitalized in the code, it also comes in foreaching. Because of the abstract list, it cannot be initialized, declaration is in a static field. The lists have the same type. import java.util.*; public class Test { public static final List<String> highPrio = Arrays.asList("*","/"); public static List<String> ops; public static void main(String[] args) { //ERROR HERE, why do it throw nullPointer? ops.addAll(highPrio); for(String s : ops) { System.out.println(s); } } }

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  • Deploy Java application on MacOSX (from a Windows system)

    - by Matías
    Hello, Here's the deal. I'm just starting with Java programming, I've made a simple application that uses SWT graphic library and I want to deploy it on a Mac (running the latest version of MacOS X). I did all the programming in my Windows 7 machine, so here are my questions: Q1) Can I make an executable file for MacOS X from my Windows machine? How? (I saw that it's possible to create .exe files on Windows, instead of using .jar; I want to do the same for the Mac, of course it won't be an .exe) Q2) If I export my project in Eclipse and I choose Runnable JAR File and then on Library Handling I pick Extract required libraries into generated JAR or Package required libraries into generated JAR I end up with a huge .JAR (about 15MB of size, my application consist in just a button on a Window and a tiny method that doesn't do much). Is that considered normal? Here's the list of libraries that my project appears to be using: Thanks in advance.

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  • Making commercial Java software

    - by roddik
    Hi. I intend to make some software to be sold over internet. I've only created open-source before, so I have really no idea of how to protect it from being cracked and distributed as warez. Bearing in mind that I know like two programms that aren't either cracked or not really useful I decided that the only more or less reliable way may look like this: Connect to a server and provide licensing info and some sort of hardware summary info If everything is fine, the server returns some crucial missing parts of the program bound to that certain pc along with the usage limit of say 2 days That crucial stuff is not saved to hard drive, so it is downloaded every time the program starts, if the programm runs more than 2 days, data is downloaded again If the same info is used from different computers, suspend the customer account What do you think about this? It may seem a bit to restrictive, but I'd better make less sales at first then eventually see my precious killer app downloaded for free. Anyways, first I need some basic theory/tutorials/guides about how to ensure that user only uses a certain Java app if he has paid for it, so please suggest some. Thanks

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  • record mouse movements, clicks and keyboard input with Java or C++

    - by Joe
    I want to be able to record mouse movements, clicks and keyboard input from a user. It would be great if it was a cross platform solution. I'd like to get back something like this (pseudo code): mouse moved to 500, 500 mouse double clicked mouse moved to 800, 300 mouse left clicked keyboard typed "Hello World" Does either C++ or Java have any classes that can do this? If I was using C++, I would probably working with the QT framework. Edit: I should have said this originally, but I want to record the movements and clicks outside of the applications gui, so on the desktop too.

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  • How to pass sockets created to another Java Process

    - by whoi
    Hi; We have an application which creates many sockets which belongs to its thread, By design if this application somehow fails, all threads stop which is not wanted. So to overcome this issue, each thread must be separated from the main application, if one of the threads fails, the other ones should be running. One thing in our mind is to pass created socket to another java process, so what is the correct way? An other approach also is welcome? Waiting for your suggestions...

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  • Java: How to clear socket bindings

    - by Matt1776
    I am having a few issues with sockets within my Java SIP client. When I bind to an address and port, if something goes wrong I have to attempt to reconnect, usually after I've stopped and restarted the process. Problem with that is then the port is bound and I am forced to increment the local port. How can I remove the binding to the port I am targeting before binding to it? If that isnt possible, then how can I trap the process just before it ends so that I can locate the socket binding and close it manually?

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  • Java Trusting ssl CA

    - by LuigiEdlCarno
    I guess I am out of ideas here. I am trying to consume a web service in java which has an ssl certificate. I createt a a keystore file in which I have added the certificate. The file lies in my project folder. I imported it using: System.setProperty("javax.net.ssl.keyStore", "folder\\keystore.jks"); System.setProperty("javax.net.ssl.keyStorePassword", "SECRET"); Apparently, the web service call checks the keystore because when giving a wrong path to the file the application throws an exception when invoking the WS, not when setting the system property. Anyway, when giving the correct path to the keystore file, I still get AxisFault faultCode: {http://xml.apache.org/axis/}HTTP faultSubcode: faultString: (401)Authorization Required Someone told me I had to trust the CA, before any of this would work. How do I do this?

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  • Java input Letter

    - by xyvyre
    I'm doing an java activity that if Name start with letter A-G and Ends with Letter H-z the output is invalid heres my code: System.out.print("Enter your name: "); String str = in.readLine(); if(str.startsWith("a" )){ System.out.print("INVALID!"); } if(str.endsWith("h")){ System.out.print("INVALID!"); } This works but how can i implement letter a to g and h to z i already try this [a-g] and it not WORK!

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  • What Java tools/apis to use for decrypting/encrypting

    - by Java_bear
    I am trying to decrypt (and later encrypt) an email message (ebXML). The message contains a Signature element that contains child elements to specify the SignedInfo, SignatureValue and KeyInfo. Also, the message contains an encrypted attachment. Question: What Java tools/apis should be used for decrypting? I would like to find some tool/api that would (automagically) instantiate objects based on whatever is included with the Signature element, so that the data (message) could be easily validated. And the other way around: Creating objects (specifying methods, signature value and keyinfo) and then outputting the xml to go into the message.

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  • retrieving 'nulls' from website using Java URL input stream

    - by Roio
    hi all, i'm trying to read the text from a website using the Java URL input stream as follows - URL u = new URL(str); br3 = new BufferedReader(new InputStreamReader(u.openStream())); while(true) System.out.println(br3.readLine()); this seems to work fine for most websites, but for some url shortening services like linkbee, the object draws a blank. e.g. http://linkbee.com/FUAKF, i can view the source code using an explorer, however i repeatedly get nulls when i use the above code.

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  • find number range in java

    - by Gandalf StormCrow
    How to get number range in java? for instance how can verify is the number 2389 within 10 numbers from 2400. its not but 2389 is. Ok here is the rephrase : Number 1000 is the range number 990 is comming in the loop, I return true because the between 990 and 1000 is 10 numbers diference. In comes the next number 989 range is always 1000, I return false because the between 989 and 1000 is 11 numbers diference. In comes the next number 1013 range is always 1000, I return false because the between 1013 and 1000 is 13 numbers diference.

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  • Duel Masters game in Java

    - by Arun Ramasubramanian
    I was trying to make a Duel Masters card game in Java using BlueJ, and came up with a lot of ideas. However, I could not exactly figure out how to sort a deck on basis of the card names in the game. I have an array of Card objects(each has, as its instance variables: String name, int cost, int civ), and I want to sort them based on name. ie: if I have the cards "Pyrofighter Magnus", "Bazagazeal Dragon" and another "Pyrofighter Magnus" in the array, the cards should be sorted on basis of their names. I know that I could use compareTo(), but is there an easier method? Anyone? Remember, the method that sorts the cards should be a modifier.

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  • illigal start of type error (java).

    - by David
    here is the relevent code snippet: public static Rand searchCount (int[] x) { int a ; int b ; int c ; int d ; int f ; int g ; int h ; int i ; int j ; Rand countA = new Rand () ; for (int l= 0; l<x.length; l++) { if (x[l] = 0) a++ ; else if (x[l] = 1) b++ ; } } return countA ; } (Rand is the name of the class that this method is in) when compiling it get this error message: Rand.java:77: illegal start of type return countA ; ^ what's going wrong here? what does this error message mean?

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  • how to return value from groovy to java

    - by Sid
    Hi I am very new to groovy and having trouble with some parts. I have a jsp page tied to a servlet that runs groovy scripts. I am able to get to the groovy script from the servlet. But after the script runs how do I return the response from the groovy script back to the servlet to be displayed in the jsp page? My java servlet code is as follows: File file = new File("TestScript.groovy"); ClassLoader parent = getClass().getClassLoader(); GroovyClassLoader loader = new GroovyClassLoader(parent); Class groovyClass = loader.parseClass(file); Object[] args = {}; GroovyObject groovyObject = (GroovyObject) groovyClass.newInstance(); groovyObject.invokeMethod("runTest", args);

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  • How to draw a filled circle in Java?

    - by Roman
    I have a JPanel with a Grid Layout. In the "cells" of the grid I can put different elements (for example JButtons). There is no problems with that. But now I want to put a filled circle in some of the cells. I also would like to relate an ActionListener with these circles. In more details, if I click the circle it disappears from the current cell and appears in another one. How can I do it in Java? I am using Swing.

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  • Java ME Runnable object takes up memory although not made an instance yet

    - by user1646684
    I am facing a strange problem with memory in Java ME. here is a part of my code: int variable=1; while (true) { if (variable==2) { display = Display.getDisplay(this); MyCanvas mc = new MyCanvas(this); // MyCanvas is a runnable object mcT = new Thread(mc); // new thread for MyCanvas mc.repaint(); display.setCurrent(mc); mcT.start(); // run thread } if (variable==1) { // Do some other stuff } } The problem is that although still the variable is set to 1, so it does not come through the if (variable==2) condition the program consumes 300kB more memory than when I delete the code after condition if (variable==2). As far as I know the code should by executed and the objects shall be created only when I set variable to value 2. But it consumes the memory also when the code after condition "if (variable==2)" is not executed. Why does this happen?

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  • how to use ByteArrayOutputStream and DataOutputStream simultaneously (Java)

    - by Manuel
    Hi! I'm having quite a problem here, and I think it is because I don't understand very much how I should use the API provided by Java. I need to write an int and a byte[] into a byte[] I thought of using a DataOutputStream to solve the data writing with writeInt(int i) and write(byte[] b), and to be able to put that into a byte array, I should use ByteArrayOutputStream's method toByteArray(). I understand that this classes use the Wrapper pattern, so I had two options: DataOutputStream w = new DataOutputStream(new ByteArrayOutputStream()); or ByteArrayOutputStream w = new ByteArrayOutputStream(new DataOutputStream()); but in both cases, I "loose" a method. in the first case, I can't access the toByteArray method, and in the second, I can't access the writeInt method. How should I use this classes together?

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  • Cant communicate with server in java

    - by cerq
    i m trying to write server to client program but i cant communicate with server in java. Below there is code block in my main. InetAddress addr = InetAddress.getLocalHost(); ipAddress = "78.162.206.164"; ServerSocket serverSocket = new ServerSocket(0); String randomStringForPlayerName = RandomStringGenerator.generateRandomString(); baseForReqOpp += ipAddress + " " + serverSocket + " " + randomStringForPlayerName; Socket socket = new Socket(host,2050); socket.setSoTimeout(100); in = new BufferedReader(new InputStreamReader(socket.getInputStream())); out = new PrintWriter(socket.getOutputStream()); out.write(baseForReqOpp); out.flush(); System.out.println(in.read()); i know there is no problem in server code and all the ports in communication are ok. But i cant read anything from server. What can be the problem?

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  • how to compress a PNG image using Java

    - by 116213060698242344024
    Hi I would like to know if there is any way in Java to reduce the size of an image (use any kind of compression) that was loaded as a BufferedImage and is going to be saved as an PNG. Maybe some sort of png imagewriteparam? I didnt find anything helpful so im stuck. heres a sample how the image is loaded and saved public static BufferedImage load(String imageUrl) { Image image = new ImageIcon(imageUrl).getImage(); bufferedImage = new BufferedImage(image.getWidth(null), image.getHeight(null), BufferedImage.TYPE_INT_ARGB); Graphics2D g2D = bufferedImage.createGraphics(); g2D.drawImage(image, 0, 0, null); return bufferedImage; } public static void storeImageAsPng(BufferedImage image, String imageUrl) throws IOException { ImageIO.write(image, "png", new File(imageUrl)); }

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  • A strange error in java generic.

    - by ???
    This is ok: Class<? extends String> stringClass = "a".getClass(); But this gets error: <T> void f(T obj) { Class<? extends T> objClass = obj.getClass(); } I know I can cast it like: <T> void f(T obj) { @SuppressWarnings("unchecked") Class<? extends T> objClass = (Class<? extends T>) obj.getClass(); } But why the previous error? Will the next release of Java 7 will support such usage?

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  • RFC822 Timezone Parsing in Java

    - by Jamen
    Hi, I have a JS date that is being converted by Dojo into RFC822 format. The function call - dojo.date.toRfc3339(jsDate), generates the following date - 2007-02-26T20:15:00+02:00. I have an application that uses a Java date SimpleDateFormat to parse in the dates generated above. I am having problems parsing this date format due to the timezone. I have attempted to use yyyy-mm-DD'T'hh:mm:ssZ This fails as the 'Z' for timezone doesn't expect a ':' character. Does anyone know how I would specify a pattern to handle a RFC822 date with the ':'? Thanks Jamen

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  • Java: Can't implement runnable on a test case: void run() collides

    - by Zombies
    So I have a test case that I want to make into a thread. I cannot extend Thread nor can I implement runnable since TestCase already has a method void run(). The compilation error I am getting is Error(62,17): method run() in class com.util.SeleneseTestCase cannot override method run() in class junit.framework.TestCase with different return type, was class junit.framework.TestResult. What I am trying to do is to scale a Selenium testcase up to perform stress testing. I am not able to use selenium grid/pushtotest.com/amazon cloud at this time (installation issues/install time/resource issues). So this really is more of a Java language issue for me.

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  • Java: set-size List issue UnsupportedOperationException thrown

    - by tuckster
    I am having a problem changing a List that has a set-size in Java. I understand that I can't add or remove from this list but why can't I use set? When I use set the UnsupportedOperationException is thrown as well as when I use add and remove which is expected. set public Object set(int index, Object element) Replaces the element at the specified position in this list with the specified element (optional operation). I understand its an optional operation its just that want to replace that one element of the list with another element. Is there any way I can do this?

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  • Java concurrency - Should block or yield?

    - by teto
    Hi, I have multiple threads each one with its own private concurrent queue and all they do is run an infinite loop retrieving messages from it. It could happen that one of the queues doesn't receive messages for a period of time (maybe a couple seconds), and also they could come in big bursts and fast processing is necessary. I would like to know what would be the most appropriate to do in the first case: use a blocking queue and block the thread until I have more input or do a Thread.yield()? I want to have as much CPU resources available as possible at a given time, as the number of concurrent threads may increase with time, but also I don't want the message processing to fall behind, as there is no guarantee of when the thread will be reescheduled for execution when doing a yield(). I know that hardware, operating system and other factors play an important role here, but setting that aside and looking at it from a Java (JVM?) point of view, what would be the most optimal?

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  • Dealing with video (DVDs, .avi .mkv) in Java

    - by berry120
    After looking around for a decent library for playing videos in Java, I've come unstuck. Everyone around is screaming not to use JMF because it's outdated, old and requires the user to install it, other alternatives such as VLCJ seem good if they work but are still relatively unstable and rely on hefty amounts of native code, and as for dealing with DVDs, I haven't found a single option available! Weighing up my options at the moment, it seems like realistically it's either JMF (despite its disadvantages) or waiting until JavaFX 2.0 comes out and then using that. VLCJ just seems too unstable which isn't really something I can live with. Are there any sensible options other than the ones I've listed above, and what would you go for? I'm not against native code per-se, but it has to be reliable and work on Windows, Mac and Linux.

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