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  • Why do transfer objects need to implement Serializable?

    - by smaye81
    I realized today that I have blindly just followed this requirement for years without ever really asking why. Today, I ran across a NotSerializableException with a model object I created from scratch and I realized enough is enough. I was told this was because of session replication between load-balanced servers, but I know I've seen other objects at session scope that do not implement Serializable. Is this the real reason?

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  • problem while rerendering the form in jsf1.1?

    - by Hari
    In my application I have to show a panel on same page after click of a button. For that I am passing my form id on rerender attribute of the button. the funtionalty is working fine but the problem is the whole form get resized and all component come close to each other. the same page i refresh the same page, then it look's fine, or if i redirect the same page again from my bean it stays fine. but i should not follow this appoach.

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  • Representing game states in Tic Tac Toe

    - by dacman
    The goal of the assignment that I'm currently working on for my Data Structures class is to create a of Quantum Tic Tac Toe with an AI that plays to win. Currently, I'm having a bit of trouble finding the most efficient way to represent states. Overview of current Structure: AbstractGame Has and manages AbstractPlayers (game.nextPlayer() returns next player by int ID) Has and intializes AbstractBoard at the beginning of the game Has a GameTree (Complete if called in initialization, incomplete otherwise) AbstractBoard Has a State, a Dimension, and a Parent Game Is a mediator between Player and State, (Translates States from collections of rows to a Point representation Is a StateConsumer AbstractPlayer Is a State Producer Has a ConcreteEvaluationStrategy to evaluate the current board StateTransveralPool Precomputes possible transversals of "3-states". Stores them in a HashMap, where the Set contains nextStates for a given "3-state" State Contains 3 Sets -- a Set of X-Moves, O-Moves, and the Board Each Integer in the set is a Row. These Integer values can be used to get the next row-state from the StateTransversalPool SO, the principle is Each row can be represented by the binary numbers 000-111, where 0 implies an open space and 1 implies a closed space. So, for an incomplete TTT board: From the Set<Integer> board perspective: X_X R1 might be: 101 OO_ R2 might be: 110 X_X R3 might be: 101, where 1 is an open space, and 0 is a closed space From the Set<Integer> xMoves perspective: X_X R1 might be: 101 OO_ R2 might be: 000 X_X R3 might be: 101, where 1 is an X and 0 is not From the Set<Integer> oMoves perspective: X_X R1 might be: 000 OO_ R2 might be: 110 X_X R3 might be: 000, where 1 is an O and 0 is not Then we see that x{R1,R2,R3} & o{R1,R2,R3} = board{R1,R2,R3} The problem is quickly generating next states for the GameTree. If I have player Max (x) with board{R1,R2,R3}, then getting the next row-states for R1, R2, and R3 is simple.. Set<Integer> R1nextStates = StateTransversalPool.get(R1); The problem is that I have to combine each one of those states with R1 and R2. Is there a better data structure besides Set that I could use? Is there a more efficient approach in general? I've also found Point<-State mediation cumbersome. Is there another approach that I could try there? Thanks! Here is the code for my ConcretePlayer class. It might help explain how players produce new states via moves, using the StateProducer (which might need to become StateFactory or StateBuilder). public class ConcretePlayerGeneric extends AbstractPlayer { @Override public BinaryState makeMove() { // Given a move and the current state, produce a new state Point playerMove = super.strategy.evaluate(this); BinaryState currentState = super.getInGame().getBoard().getState(); return StateProducer.getState(this, playerMove, currentState); } } EDIT: I'm starting with normal TTT and moving to Quantum TTT. Given the framework, it should be as simple as creating several new Concrete classes and tweaking some things.

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  • How to get IzPack tocheck for an existing version of the software?

    - by bguiz
    Hi, I have an application for which we use IzPack to create the installer. The installer is working fine in its current state, however, I need to add functionality that enables it to check whether an existing version of the software has been installed. I understand IzPack supports this out of the box using its CheckedHelloPanel, unfortunately that only works for Windows, as it appears to depend on the windows registry. Is there a way to configure IzPack such that it is able to detect existing installations? I need to be able to detect whether there is one and merely display a message notifying the user... Bonus points for how to give the user the option to trigger the uninstaller of the existing installation. Assume that the software will only be installed using the new installer IzPack only: please do not suggest alternatives, as we cannot change that now If you suggest using <validator>, please include a code sample of the validator class, because I have considered this, but don't know where to start

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  • Python code translation to JVM

    - by jldupont
    Is there such a thing as a "translator" (for lack of a better word in my mind now) that translates Python code directly to JVM / Dalvik bytecode? Would be great for writing Android applications in Python! NOTE: I know about the scripting capabilities of the Android platform but I am looking for something that would generate a '.apk' without having to install the 'scripting' package... annoying for end-users.

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  • Creating queries using Criteria API (JPA 2.0)

    - by Pym
    Hello there ! I'm trying to create a query with the Criteria API from JPA 2.0, but I can't make it work. The problem is with the "between" conditionnal method. I read some documentation to know how I have to do it, but since I'm discovering JPA, I don't understand why it does not work. First, I can't see "creationDate" which should appear when I write "Transaction_." I thought it was maybe normal, since I read the metamodel was generated at runtime, so I tried to use 'Foo_.getDeclaredSingularAttribute("value")' instead of 'Foo_.value', but it still doesn't work at all. Here is my code : public List<Transaction> getTransactions(Date startDate, Date endDate) { EntityManager em = getEntityManager(); try { CriteriaBuilder cb = em.getCriteriaBuilder(); CriteriaQuery<Transaction> cq = cb.createQuery(Transaction.class); Metamodel m = em.getMetamodel(); EntityType<Transaction> Transaction_ = m.entity(Transaction.class); Root<Transaction> transaction = cq.from(Transaction.class); // Error here. cannot find symbol. symbol: variable creationDate cq.where(cb.between(transaction.get(Transaction_.creationDate), startDate, endDate)); // I also tried this: // cq.where(cb.between(Transaction_.getDeclaredSingularAttribute("creationDate"), startDate, endDate)); List<Transaction> result = em.createQuery(cq).getResultList(); return result; } finally { em.close(); } } Can someone help me to figure this out? Thanks.

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  • Testing JavaMail Related Modules

    - by Hamza Yerlikaya
    Part of my application depends on JavaMail, moving arranging messages etc. Is it possible to test this module without firing a IMAP server to run the tests on? I am always stuck when it comes to testing stuff that depends on external servers or modules.

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  • May the FileInputStream.available foolish me?

    - by Tom Brito
    This FileInputStream.available() javadoc says: Returns an estimate of the number of remaining bytes that can be read (or skipped over) from this input stream without blocking by the next invocation of a method for this input stream. The next invocation might be the same thread or another thread. A single read or skip of this many bytes will not block, but may read or skip fewer bytes. In some cases, a non-blocking read (or skip) may appear to be blocked when it is merely slow, for example when reading large files over slow networks. I'm not sure if in this check: if (new FileInputStream(xmlFile).available() == 0) can I rely that empty files will always return zero?

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  • Textbox height in a small browser window

    - by Fritz H
    Hi folks, I have here a peculiar problem. We have a RAP application intended for use on a PDA/phone, but when it is displayed in a small browser window, all the textboxes on the form(s) are too tall (around twice the height they should be). I've stepped through the code (The form is using GridLayout, number of columns=1, make columns equal=false) and have found that the TextSizeDetermination.getCharHeight() method returns an incorrect font size if the browser window is too small - 13px if the window is large, 26px (exactly double) if the window is too small. Interestingly enough, it seems that if the window is too small, probeStore.containsProbeResult(font) in that method returns true and uses probeStore.getProbeResult(...).getSize().y for the font size. Otherwise, if the window is larger, it returns false and uses TextSizeEstimation.getCharHeight(...). Does anyone have a pointer or two for getting around this? Dialog with a properly-sized window: Dialog with a small window:

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  • Spring WS & Validator interceptor

    - by mada
    I have a endpoint mapping a webservice which is used to insert in the dabatabase some keywords: @Transactional(readOnly = false,isolation= Isolation.SERIALIZABLE) public Source saveKW(...). The input is a request. I would like to add an interceptor on the method in order to validate the parameters. this one will read some values from the DB. i would like that this interceptor is EMBED in the transaction declared for the endpoint (or this opposite). In other words, i want them to be in the same transaction. Ideally im looking for something like this with annotation: @Transactional(readOnly = false,isolation= Isolation.SERIALIZABLE) @validator("KeyWordValidaor.class") public Source saveKW(...) where KeyWordValidaor will be class validating the parameters. Have you any idea or short examples to implements this like this way or in a other real way?

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  • Spring validation errors not displayed

    - by Art Vandelay
    I have the following situation. I have a validator to validate my command object and set the errors on a Errors object to be displayed in my form. The validator is invoked as expected and works okay, but the errors i set on the Errors objects are not displayed, when i am sent back to my form because of the validation errors. Validator: public void validate(Object obj, Errors err) { MyCommand myCommand = (MyCommand) obj; int index = 0; for (Field field : myCommand.getFields()) { if (field.isChecked()) { if ((field.getValue() == null) || (field.getValue().equals(""))) { err.rejectValue("fields[" + index + "].value", "errors.missing"); } } index++; } if (myCommand.getLimit() < 0) { err.rejectValue("limit", "errors.invalid"); } } Command: public class MyCommand { private List<Field> fields; private int limit; //getters and setters } public class Field { private boolean checked; private String name; private String value; //getters and setters } Form: <form:form id="myForm" method="POST" action="${url}" commandName="myCommand"> <c:forEach items="${myCommand.fields}" var="field" varStatus="status"> <form:checkbox path="fields[${status.index}].checked" value="${field.checked}" /> <c:out value="${field.name}" /> <form:input path="fields[${status.index}].value" /> <form:errors path="fields[${status.index}].value" cssClass="error" /></td> <form:hidden path="fields[${status.index}].name" /> </c:forEach> <fmt:message key="label.limit" /> <form:input path="limit" /> <form:errors path="limit" cssClass="error" /> </form:form> Controller: @RequestMapping(value = REQ_MAPPING, method = RequestMethod.POST) public String onSubmit(Model model, MyCommand myCommand, BindingResult result) { // validate myCommandValidator.validate(myCommand, result); if (result.hasErrors()) { model.addAttribute("myCommand", myCommand); return VIEW; } // form is okay, do stuff and redirect } Could it be that the paths i give in the validator and tag are not correct? The validator validates a command object containing a list of objects, so that's why i give a index on the list in the command object when registering an error message (for example: "fields["+index+"]".value). Or is it that the Errors object containing the errors is not available to my view? Any help is welcome and appreciated, it might give me a hint or point me in right direction.

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  • Space-based architecture?

    - by rcampbell
    One chapter in Pragmatic Programmer recommends looking at a blackboard/space-based architecture + a rules engine as a more flexible alternative to a traditional workflow system. The project I'm working on currently uses a workflow engine, but I'd like to evaluate alternatives. I really feel like a SBA would be a better solution to our business problems, but I'm worried about a total lack of community support/user base/venders/options. JavaSpaces is dead, and the JINI spin-off Apache River seems to be on life support. SemiSpace looks perfect, but it's a one-man show. The only viable solution seems to be GigaSpaces. I'd like to hear your thoughts on space based architecture and any experiences you've had with real world implementations.

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  • How do I determine if a JDialog has children?

    - by Morinar
    I've got a custom window class that is a couple levels down extending a JDialog. We have windows that we create and sometimes we create new windows as children of existing windows using the constructor that takes a parent argument. I need to put some code somewhere in our custom class that does something different depending on whether not the window has children. I know of getParent(), etc, and I can see that I can loop through the components of the window, but for the life of me, I can't seem to figure out how to determine whether or not my current window has any child windows. Is there a way to do this? Any help is, as always, much appreciated.

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  • toString method for varargs contructor

    - by owca
    I have a varargs contructor like this : public class Sentence { public String[] str; public Sentence(Object... text){ StringBuilder sb = new StringBuilder(); for (Object o : text) { sb.append(o.toString()) .append(" "); } System.out.println(sb.toString()); } } Contructor can get various types of data (ints, strings, and Sentence objects as well). How to do a proper toString method for such class ?

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  • Mismatched coordinate systems in LWJGL with Mouse and Textures

    - by Braains
    I'm not really sure how to expand on this other than to say that it appears that my LWJGL seems to have different coordinate systems for the Mouse and for painting Textures. It seems that Textures have the usual Java2D way of putting (0, 0) in the upper-left corner, while the Mouse goes by the more sensible way of having the origin in the lower-left corner. I've checked my code a bunch but I don't see anything modifying the values between where I read them and where I use them. It's thrown me for a loop and I can't quite figure it out. I'll post all the code that involves the Mouse input and Texture painting for you guys to look at. private static void pollHelpers() { while(Mouse.next()) { InputHelper.acceptMouseInput(Mouse.getEventButton(), Mouse.getEventX(), Mouse.getEventY()); } while (Keyboard.next()) { if (Keyboard.getEventKeyState()) { InputHelper.acceptKeyboardInput(Keyboard.getEventKey(), true); } else { InputHelper.acceptKeyboardInput(Keyboard.getEventKey(), false); } } } public static void acceptMouseInput(int mouseButton, int x, int y) { for(InputHelper ie: InputHelper.instances) { if(ie.checkRectangle(x, y)) { ie.sendMouseInputToParent(mouseButton); } } } private void sendMouseInputToParent(int mouseButton) { parent.onClick(mouseButton); } public boolean checkRectangle(int x, int y) { //y = InputManager.HEIGHT - y; See below for explanation return x > parent.getX() && x < parent.getX() + parent.getWidth() && y > parent.getY() && y < parent.getY() + parent.getHeight(); } I put this line of code in because it temporarily fixed the coordinate system problem. However, I want to have my code to be as independent as possible so I want to remove as much reliance on other classes as possible. These are the only methods that touch the Mouse input, and as far as I can tell none of them change anything so all is good here. Now for the Texture methods: public void draw() { if(!clicked || deactivatedImage == null) { activatedImage.bind(); glBegin(GL_QUADS); { DrawHelper.drawGLQuad(activatedImage, x, y, width, height); } glEnd(); } else { deactivatedImage.bind(); glBegin(GL_QUADS); { DrawHelper.drawGLQuad(deactivatedImage, x, y, width, height); } glEnd(); } } public static void drawGLQuad(Texture texture, float x, float y, float width, float height) { glTexCoord2f(x, y); glVertex2f(x, y); glTexCoord2f(x, y + texture.getHeight()); glVertex2f(x, y + height); glTexCoord2f(x + texture.getWidth(), y + texture.getHeight()); glVertex2f(x + width, y +height); glTexCoord2f(x + texture.getWidth(), y); glVertex2f(x + width, y); } I'll be honest, I do not have the faintest clue as to what is really happening in this method but I was able to put it together on my own and get it to work. my guess is that this is where the problem is. Thanks for any help!

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  • Unit testing Jade

    - by Strawberry
    Hi, What techniques and design strategies have people used to aid in unit testing Jade applications? In particular, how do people typically go about testing Behaviours - which are tightly coupled to the Agent instance and the Jade environment? I'm aware of the JadeMX project, but this appears to be geared more towards system testing - in particular the message exchange between collaborating agents. Thanks.

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  • Apache with JBOSS using AJP (mod_jk) giving spikes in thread count.

    - by Beginner
    We used Apache with JBOSS for hosting our Application, but we found some issues related to thread handling of mod_jk. Our website comes under low traffic websites and has maximum 200-300 concurrent users during our website's peak activity time. As the traffic grows (not in terms of concurrent users, but in terms of cumulative requests which came to our server), the server stopped serving requests for long, although it didn't crash but could not serve the request till 20 mins. The JBOSS server console showed that 350 thread were busy on both servers although there was enough free memory say, more than 1-1.5 GB (2 servers for JBOSS were used which were 64 bits, 4 GB RAM allocated for JBOSS) In order to check the problem we were using JBOSS and Apache Web Consoles, and we were seeing that the thread were showing in S state for as long as minutes although our pages take around 4-5 seconds to be served. We took the thread dump and found that the threads were mostly in WAITING state which means that they were waiting indefinitely. These threads were not of our Application Classes but of AJP 8009 port. Could somebody help me in this, as somebody else might also got this issue and solved it somehow. In case any more information is required then let me know. Also is mod_proxy better than using mod_jk, or there are some other problems with mod_proxy which can be fatal for me if I switch to mod__proxy? The versions I used are as follows: Apache 2.0.52 JBOSS: 4.2.2 MOD_JK: 1.2.20 JDK: 1.6 Operating System: RHEL 4 Thanks for the help.

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  • "org.json.JSONArray implements Serializable": What's the best option to achieve this?

    - by Daxon
    I am using Grails Webflow, what ever object I pass to a view, it must be Serialized. My domain models "implement Serializable", so they work. The problem is when I get a response from a WebService. It is of the org.json.JSONArray class. I just want to pass the whole Array over to the view yet it doesn't implement Serializable, so it fails, Any thoughts on how I can pass this, or my best option? Can I just edit the source of the org.json library and make every class "imp Serializable"? Or process the result into Domain objects that do "imp Serializable"

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  • Limiting one of each Runnable type in ExecutorService queue.

    - by Andrew
    I have an Executors.newFixedThreadPool(1) that I send several different tasks to (all implementing Runnable), and they get queued up and run sequentially correct? What is the best way to only allow one of each task to be either running or queued up at one time? I want to ignore all tasks sent to the ExecutorService that are already in the queue.

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  • JPA - Performance with using multiple entity manager

    - by Nguyen Tuan Linh
    My situation is: The code is not mine I have two kinds of database: one is Dad, one is Son. In Dad, I have a table to store JNDI name. I will look up Dad using JNDI, create entity manager, and retrieve this table. From these retrieved JNDI names, I will create multiple entity managers using multiple Son databases. The problem is: Son have thousands of entities. It takes each Son database around 10 minutes to load all entities. If there is 4 Son databases, it will be 40 minutes. My question: Is there any way to load all entities and use them for all entity manager? Please look at the code below For each Son JNDI: Map<String, String> puSonProperties = new HashMap<String, String>(); puSonProperties.put("javax.persistence.jtaDataSource", sonJndi); EntityManagerFactory emf = Persistence.createEntityManagerFactory("PUSon", puSonProperties); PUSon - All of them use the same persistence unit log.info("Verify entity manager for son: {0} - {1}", sonCode, emSon.find(Son_configuration.class, 0) != null ? "ok" : "failed!"); This is the actual code where the loading of all entities begins. 10 mins.

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  • Should I use a collection here?

    - by Eva
    So I have code set up like this: public interface IInterface { public void setField(Object field); } public abstract class AbstractClass extends JPanel implements IInterface { private Object field_; public void setField(Object field) { field_ = field; } } public class ClassA extends AbstractClass { public ClassA() { // unique ClassA constructor stuff } public Dimension getPreferredSize() { return new Dimension(1, 1); } } public class ClassB extends AbstractClass { public ClassB() { // unique ClassB constructor stuff } public Dimension getPreferredSize() { return new Dimension(42, 42); } } public class ConsumerA { public ConsumerA(Collection<AbstractClass> collection) { for (AbstractClass abstractClass : collection) { abstractClass.setField(this); abstractClass.repaint(); } } } All hunky-dory so far, until public class ConsumerB { // Option 1 public ConsumerB(ClassA a, ClassB b) { methodThatOnlyTakesA(a); methodThatOnlyTakesB(b); } // Option 2 public ConsumerB(Collection<AbstractClass> collection) { for (IInterface i : collection) { if (i instanceof ClassA) { methodThatOnlyTakesA((ClassA) i); else if (i instanceof ClassB) { methodThatOnlyTakesB((ClassB) i); } } } } public class UsingOption1 { public static void main(String[] args) { ClassA a = new ClassA(); ClassB b = new ClassB(); Collection<AbstractClass> collection = Arrays.asList(a, b); ConsumerA consumerA = new ConsumerA(collection); ConsumerB consumerB = new ConsumerB(a, b); } } public class UsingOption2 { public static void main(String[] args) { Collection<AbstractClass> collection = Arrays.asList(new ClassA(), new ClassB()); ConsumerA = new ConsumerA(collection); ConsumerB = new ConsumerB(collection); } } With a lot more classes extending AbstractClass, both options get unwieldly. Option1 would make the constructor of ConsumerB really long. Also UsingOption1 would get long too. Option2 would have way more if statements than I feel comfortable with. Is there a viable Option3? If it helps, ClassA and ClassB have all the same methods, they're just implemented differently. Thanks for slogging through my code!

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  • Difference in output from use of synchronized keyword and join()

    - by user2964080
    I have 2 classes, public class Account { private int balance = 50; public int getBalance() { return balance; } public void withdraw(int amt){ this.balance -= amt; } } and public class DangerousAccount implements Runnable{ private Account acct = new Account(); public static void main(String[] args) throws InterruptedException{ DangerousAccount target = new DangerousAccount(); Thread t1 = new Thread(target); Thread t2 = new Thread(target); t1.setName("Ravi"); t2.setName("Prakash"); t1.start(); /* #1 t1.join(); */ t2.start(); } public void run(){ for(int i=0; i<5; i++){ makeWithdrawl(10); if(acct.getBalance() < 0) System.out.println("Account Overdrawn"); } } public void makeWithdrawl(int amt){ if(acct.getBalance() >= amt){ System.out.println(Thread.currentThread().getName() + " is going to withdraw"); try{ Thread.sleep(500); }catch(InterruptedException e){ e.printStackTrace(); } acct.withdraw(amt); System.out.println(Thread.currentThread().getName() + " has finished the withdrawl"); }else{ System.out.println("Not Enough Money For " + Thread.currentThread().getName() + " to withdraw"); } } } I tried adding synchronized keyword in makeWithdrawl method public synchronized void makeWithdrawl(int amt){ and I keep getting this output as many times I try Ravi is going to withdraw Ravi has finished the withdrawl Ravi is going to withdraw Ravi has finished the withdrawl Ravi is going to withdraw Ravi has finished the withdrawl Ravi is going to withdraw Ravi has finished the withdrawl Ravi is going to withdraw Ravi has finished the withdrawl Not Enough Money For Prakash to withdraw Not Enough Money For Prakash to withdraw Not Enough Money For Prakash to withdraw Not Enough Money For Prakash to withdraw Not Enough Money For Prakash to withdraw This shows that only Thread t1 is working... If I un-comment the the line saying t1.join(); I get the same output. So how does synchronized differ from join() ? If I don't use synchronize keyword or join() I get various outputs like Ravi is going to withdraw Prakash is going to withdraw Prakash has finished the withdrawl Ravi has finished the withdrawl Prakash is going to withdraw Ravi is going to withdraw Prakash has finished the withdrawl Ravi has finished the withdrawl Prakash is going to withdraw Ravi is going to withdraw Prakash has finished the withdrawl Ravi has finished the withdrawl Account Overdrawn Account Overdrawn Not Enough Money For Ravi to withdraw Account Overdrawn Not Enough Money For Prakash to withdraw Account Overdrawn Not Enough Money For Ravi to withdraw Account Overdrawn Not Enough Money For Prakash to withdraw Account Overdrawn So how does the output from synchronized differ from join() ?

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  • Displaying large file in JTextArea.

    - by Sathish Gopal
    Hi All, I'm currently working in Swing UI Assignment. This work involves showing large file content in JTextArea. The file size can be as large as 2 GB. My initial idea is to lazily load content from the file, say 1 MB of content will be shown to the user. As the user scrolls i will retrieve the next 1 MB of content to be shown. All these operation will be happening in background thread (Swing Worker). I looked at the JTextArea API, the method insert takes String and int(position of the insert) as the parameter. This will suffice, but i'm worried about performance, because the content (1 MB at a time) retrieved will have to be converted to String object. Is there any other work around or any other alternative/better solution for this.

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