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  • JButtons re-enable themselves after being disabled

    - by Anarchist
    I have an array of JButtons which form a keypad interface. After six numbers are entered I want to disable the keypad so that no further numbers can be entered by the user. I have written the code and the buttons do disable until the mouse hovers above any of them, then the buttons seem to re-enable themselves and run actionEvents added to them. The full code is available here. Possible things that I think are wrong. There is some sort of MouseListener which is ignoring when I set button.setEnabled(false); I haven't separated attributes from the buildGUI(); correctly, I only did this anyway so that the inner class could access them. Possibly something to do with the gridLayout as disabling the buttons seems to work for my services JPanel buttons.

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  • Why new String(bytes, enc).getBytes(enc) does not return the original byte array?

    - by Bozho
    I made the following "simulation": byte[] b = new byte[256]; for (int i = 0; i < 256; i ++) { b[i] = (byte) (i - 128); } byte[] transformed = new String(b, "cp1251").getBytes("cp1251"); for (int i = 0; i < b.length; i ++) { if (b[i] != transformed[i]) { System.out.println("Wrong : " + i); } } For cp1251 this outputs only one wrong byte - at position 23. For KOI8-R - all fine. For cp1252 - 4 or 5 differences. What is the reason for this and how can this be overcome? I know it is wrong to represent byte arrays as strings in whatever encoding, but it is a requirement of the protocol of a payment provider, so I don't have a choice. Update: representing it in ISO-8859-1 works, and I'll use it for the byte[] part, and cp1251 for the textual part, so the question remains only out of curiousity

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  • Character encoding issues?

    - by Santosh
    We had a a clob column in DB. Now when we extract this clob and try to display it (plain text not html), it prints junk some characters on html screen. The character when directly streamed to a file looks like ” (not the usual double quote on regular keyboard) One more observation: System.out.println("”".getBytes()[0]); prints -108. Why a character byte should be in negative range ? Is there any way to display it correctly on a html screen ?

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  • Best practice for passing configuration to each GUI object

    - by Laimoncijus
    Hi, I am writing an application, where I do have few different windows implemented, where each window is a separate class. Now I need somehow to pass a single configuration object to all of them. My GUI is designed in way, where I have one main window, which may create some child windows of its own, and these child windows can have their own childs (so there is no possibility to create all windows in initialization part and feed the config object to all of them from the very beginning)... What would be best practice for sharing this configuration object between them? Always passing via constructor or maybe making it somewhere as final public static and let each window object to access it when needed? Thanks

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  • Openid for google apps domain

    - by user268515
    Hi I'm new to openId concepts. I want to use my google apps domain's user-name & password in third party websites for that i followed this link http://jeremiahlee.com/blog/2009/09/28/how-to-setup-openid-with-google-apps/. But i got struck on second step i dont know where and how to create openId file in server.Please Help on this issue it will be very useful for me. Thanks, Sharun.

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  • Is there any point in using a volatile long?

    - by Adamski
    I occasionally use a volatile instance variable in cases where I have two threads reading from / writing to it and don't want the overhead (or potential deadlock risk) of taking out a lock; for example a timer thread periodically updating an int ID that is exposed as a getter on some class: public class MyClass { private volatile int id; public MyClass() { ScheduledExecutorService execService = Executors.newScheduledThreadPool(1); execService.scheduleAtFixedRate(new Runnable() { public void run() { ++id; } }, 0L, 30L, TimeUnit.SECONDS); } public int getId() { return id; } } My question: Given that the JLS only guarantees that 32-bit reads will be atomic is there any point in ever using a volatile long? (i.e. 64-bit). Caveat: Please do not reply saying that using volatile over synchronized is a case of pre-optimisation; I am well aware of how / when to use synchronized but there are cases where volatile is preferable. For example, when defining a Spring bean for use in a single-threaded application I tend to favour volatile instance variables, as there is no guarantee that the Spring context will initialise each bean's properties in the main thread.

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  • Ensuring all waiting threads complete

    - by Daniel
    I'm building a system where the progress of calling threads is dependent on the state of two variables. One variable is updated sporadically by an external source (separate from the client threads) and multiple client threads block on a condition of both variables. The system is something like this TypeB waitForB() { // Can be called by many threads. synchronized (B) { while (A <= B) { B.wait(); } A = B; return B; { } void updateB(TypeB newB) { // Called by one thread. synchronized (B) { B.update(newB); B.notifyAll(); // All blocked threads must receive new B. } } I need all the blocked threads to receive the new value of B once it has been updated. But the problem is once a single thread finishes and updates A, the waiting condition becomes true again so some of the other threads become blocked and don't receive the new value of B. Is there a way of ensuring that only the last thread that was blocked on B updates A, or another way of getting this behaviour?

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  • are there requirements for Struts setters beyond variable name matching?

    - by slk
    I have a model-driven Struts Web action: public class ModelDrivenAction<T extends Object> implements ModelDriven<T>, Preparable { protected Long id; protected T model; @Override public void prepare() {} public void setId(Long id) { this.id = id; } @Override public T getModel() { return model; } public void setModel(T model) { this.model = model; } } I have another action which is not currently model-driven: public class OtherAction implements Preparable { private ModelObj modelObj; private Long modelId; @Override public void prepare() { modelObj = repoService.retrieveModelById(modelId); } public void setModelId(Long modelId) { this.modelId = modelId; } } I wish to make it so, and would like to avoid having to track down all the instances in JavaScript where the action is passed a "modelId" parameter instead of "id" if at all possible. I thought this might work, so either modelId or id could be passed in: public class OtherAction extends ModelDrivenAction<ModelObj> { @Override public void prepare() { model = repoService.retrieveModelById(id); } public void setModelId(Long modelId) { this.id = modelId; } } However, server/path/to/other!method?modelId=123 is failing to set id. I thought so long as a setter matched a parameter name the Struts interceptor would call it on action invocation. Am I missing something here?

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  • can't understand the url function used in the google taskque api documentation

    - by Bunny Rabbit
    import com.google.appengine.api.labs.taskqueue.Queue; import com.google.appengine.api.labs.taskqueue.QueueFactory; import static com.google.appengine.api.labs.taskqueue.TaskOptions.Builder.*; // ... Queue queue = QueueFactory.getDefaultQueue(); queue.add(url("/worker").param("key", key)) in the code example given on the google task queue documentation page i can't understand the url("/worker") function they are calling in the queues.add() invocation .

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  • Implementing clone on a LinkedList

    - by devoured elysium
    I am trying to implement a clone() method on a DoubleLinkedList. Now, the problem is that implementing it by "the convention" is a lot more troublesome than just creating a new DoubleLinkedList and filling it with all the elements of my current DoubleLinkedList. Is there any inconvenient I am not seeing when doing that? Here is my current approach: @Override public DoubleLinkedList<T> clone() { DoubleLinkedList<T> dll = new DoubleLinkedList<T>(); for (T element : dll) { dll.add(element); } return dll; } Here is what it would be by the convention: @Override public DoubleLinkedList<T> clone() { try { DoubleLinkedList<T> dll = (DoubleLinkedList<T>)super.clone(); //kinda complex code to copy elements return dll; } catch (CloneNotSupportedException e) { throw new InternalError(e.toString()); } }

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  • Why is my quick sort so slow?

    - by user513075
    Hello, I am practicing writing sorting algorithms as part of some interview preparation, and I am wondering if anybody can help me spot why this quick sort is not very fast? It appears to have the correct runtime complexity, but it is slower than my merge sort by a constant factor of about 2. I would also appreciate any comments that would improve my code that don't necessarily answer the question. Thanks a lot for your help! Please don't hesitate to let me know if I have made any etiquette mistakes. This is my first question here. private class QuickSort implements Sort { @Override public int[] sortItems(int[] ts) { List<Integer> toSort = new ArrayList<Integer>(); for (int i : ts) { toSort.add(i); } toSort = partition(toSort); int[] ret = new int[ts.length]; for (int i = 0; i < toSort.size(); i++) { ret[i] = toSort.get(i); } return ret; } private List<Integer> partition(List<Integer> toSort) { if (toSort.size() <= 1) return toSort; int pivotIndex = myRandom.nextInt(toSort.size()); Integer pivot = toSort.get(pivotIndex); toSort.remove(pivotIndex); List<Integer> left = new ArrayList<Integer>(); List<Integer> right = new ArrayList<Integer>(); for (int i : toSort) { if (i > pivot) right.add(i); else left.add(i); } left = partition(left); right = partition(right); left.add(pivot); left.addAll(right); return left; } }

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  • JList strike through

    - by kap
    I have a list of data in a JList component in my GUI. I would like to know if there is a method that i can call on the list element(s) to strike through a particular element in the list. I would like to draw a line through the element to appear as if that element is canceled. I want a similar thing like the strike through functionality in Microsoft Word document whereby a line i drawn through the text. thanks for your help

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  • What to do when ServerSocket throws IOException

    - by s5804
    Basically I want to create a rock solid server. while (keepRunning.get()) { try { Socket clientSocket = serverSocket.accept(); ... spawn a new thread to handle the client ... } catch (IOException e) { e.printStackTrace(); // NOW WHAT? } } In the IOException block, what to do? Is the Server socket at fault so it need to be recreated? For example wait a few seconds and then serverSocket = ServerSocketFactory.getDefault().createServerSocket(MY_PORT); However if the server socket is still OK, then it is a pity to close it and kill all previously accepted connections that are still communicating.

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  • pattern to transfer search model to dao

    - by zeroed
    We have a dao as a project (jar file). Clients use its interfaces and factories to operate with database. Using standard CRUD operations, dao allows you to search an entity by some search criteria. What is the best way to represent this criteria? Is transfer object appropriate pattern in this situation? How should client create SearchModel instance? Please, share. Regards.

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  • Why is hibernate returning a proxy object?

    - by predhme
    I have a service method that returns an object from the database. This method is called from numerous parts of the system. However, one particular method is getting a return type of ObjectClass_$$_javassist_somenumber as the type. Which is throwing things off. I call the service method exactly the same as everywhere else, so why would hibernate return the proxy as opposed to the natural object? I know there are ways to expose the "proxied" object, but I don't feel like I should have to do that. The query is simply hibernateTemplate.find("from User u where u.username = ?", username)

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  • Has anyone tried the "objectify" library for Google App Engine?

    - by Spines
    I was using JDO for my google app engine project but got fed up with the additional 5 seconds it adds to my cold start time. I was planning on just writing stuff directly to the database with the low level datastore api, but then I came accross the objectify project ( http://code.google.com/p/objectify-appengine/ ). Apparently its a super light wrapper above the low level api. Does anyone have experiences with this library that they could share?

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  • Selecting multiple cached elements

    - by Globalz
    In jQuery you can select two elements by id like: $('#elem, #elem2'); BUT What if you have cached the elem and elem2, and what to apply the same method/function to them both? i.e. $elem = $('#elem'); $elem2 = $('#elem2'); This obviously wont work: $($elem, $elem2) Thanks!

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  • Loading data from file to Vector structure

    - by owca
    I'm trying to parse through fixed-width formatted file extracting x,y values of points from it, and then storing them in int[] array inside a Vector. Text file looks as follows : 0006 0015 0125 0047 0250 0131 That's the code : Vector<int[]> vc = new Vector<int[]>(); try { BufferedReader file = new BufferedReader(new FileReader("myfile.txt")); String s; int[] vec = new int[2]; while ((s = file.readLine()) != null) { vec[0] = Integer.parseInt(s.substring(0, 4).trim()); vec[1] = Integer.parseInt(s.substring(5, 8).trim()); vc.add(vec); } file.close(); } catch (IOException e) { } for(int i=0; i<vc.size(); i++){ for(int j=0; j<2; j++){ System.out.println(vc.elementAt(i)[j]); } } But the output shows only last line. 250 131 250 131 250 131 Should I somehow use Vector.nextElement() here to get all my data ?

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  • Auto injecting logger with guice

    - by koss
    With reference to Guice's custom injections article, its TypeListener performs a check for InjectLogger.class annotation - which can be optional. Removing that check will inject to all Logger.class types. class Log4JTypeListener implements TypeListener { public <T> void hear(TypeLiteral<T> typeLiteral, TypeEncounter<T> typeEncounter) { for (Field field : typeLiteral.getRawType().getDeclaredFields()) { if (field.getType() == Logger.class && field.isAnnotationPresent(InjectLogger.class)) { typeEncounter.register(new Log4JMembersInjector<T>(field)); } } } } I'm tempted to remove "&& field.isAnnotationPresent(InjectLogger.class)" from the listener. If we're using Guice to inject all instances of our Logger, is there any reason not to do it automatically (without need to annotate)?

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