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  • readObject() vs. readResolve() to restore transient fields

    - by Joonas Pulakka
    According to Serializable javadoc, readResolve() is intended for replacing an object read from the stream. But is it OK to use it for restoring transient fields, like so: private Object readResolve() { transientField = something; return this; } as opposed to using readObject(): private void readObject(ObjectInputStream s) { s.defaultReadObject(); transientField = something; } Is there any reason to choose one over other, when used to just restore transient fields?

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  • What is design principle behind Servlets being Singleton

    - by Sandeep Jindal
    A servlet container "generally" create one instance of a servlet and different threads of the same instance to serve multiple requests. (I know this can be changed using deprecated SingleThreadModel and other features, but this is the usual way). I thought, the simple reason behind this is performance gain, as creating threads is better than creating instances. But it seems this is not the reason. On the other hand, creating instances have little advantage that developers never have to worry about thread safety. I am trying to understand the reason for this decision over the trade-off of thread-safety.

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  • How to change order in ordered+persisted collection?

    - by Jaroslav Záruba
    I just need to change order of items in a (previously persisted) ordered collection... I tried simply passing the re-arranged collection to a setter: after committing a transaction the collection is gone. Then I tried to clear() the existing collection and addAll() afterwards: clear() makes persistent manager to mark all the elements as deleted. (But obviously I would like to be able to work with the collection items in the very transaction.) (The collection is not in a default fetch group, so I tried the above also with the named fetch group added into the fetch plan. No luck.) This must be the most stupid question, but I ran out of ideas and I'm stuck here two days already. I swear I googled. :(

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  • How to use a jar in Unity3D?

    - by Dima Goltsman
    I have a jar library that i created. It can be integrated in any android app and it works like this: String token="<SOME_TOKEN>"; DeviceIdentifier edDevice = new DeviceIdentifier( this.getApplicationContext(),token); edDevice.update(); DeviceIdentifier class os a class in the jar. now i want to make that jar work with Unity3d, i searched the web and couldn't find anything what is the correct way to integrate it?

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  • Better to use constructor or method factory pattern?

    - by devoured elysium
    I have a wrapper class for the Bitmap .NET class called BitmapZone. Assuming we have a WIDTH x HEIGHT bitmap picture, this wrapper class should serve the purpose of allowing me to send to other methods/classes itself instead of the original bitmap. I can then better control what the user is or not allowed to do with the picture (and I don't have to copy the bitmap lots of times to send for each method/class). My question is: knowing that all BitmapZone's are created from a Bitmap, what do you find preferrable? Constructor syntax: something like BitmapZone bitmapZone = new BitmapZone(originalBitmap, x, y, width, height); Factory Method Pattern: BitmapZone bitmapZone = BitmapZone.From(originalBitmap, x , y, width, height); Factory Method Pattern: BitmapZone bitmapZone = BitmapZone.FromBitmap(originalBitmap, x, y, width, height); Other? Why? Thanks

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  • NetBeans parameter fill after code completion

    - by byte
    This is a particularly annoying problem I'm having, and I can't be the only one to have issue with it. In NetBeans, when you type part of a method, then hit CTRL-SPACE, it displays the code-completion popup, whereupon you can hit tab to finish out the word. This is great, and pretty much how all IDE's operate. Example: Thread.sl < CTRL-SPACE Thread.sleep Yay! Problem is that in this context, once you type in a paren, it auto-fills the parameters for the method with their default names, and inserts a closing paren (regardless of whether you have disabled the option to automatically close them on the preferences page for code completion). This behavior is NOT present if you had manually typed out the full name. How is this helpful to anyone? You've got to type over it your actual variable that you will be passing, and NetBeans gives you no option to prevent the closing paren on code-completion. Does anyone have a way to solve this issue, without having to dive into the netbeans source and build it just for this minor of an issue?

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  • How to change a Datasource's username/password at runtime in a J2EE app?

    - by Toto
    I've deployed a web-module which connects to the database via a datasource configured in the J2EE application server. Currently, the user/password for the database connection is set in the proper J2EE application server's datasources configuration file. I want to change during runtime the datasource's user/password. (e.g.: implement a new web form in which the user is asked to enter de user/password to be used in the database connection). Is there a standard way to do that in J2EE applications or it depends on the J2EE application server? In this case I'm using Orion application server.

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  • Junit exception test

    - by Prithis
    I have two tests to check the expected exception throw. I am using Junit 4 and has following syntax. @Test(expected=IllegalArgumentException.class) public void testSomething(){ .......... } One of the tests fail even though IllegalArgumentException is thrown and the other passes. Any idea whats missing?? I modified the test which is failing to following and it passes. public void testSomething(){ try{ ............ //line that throws exception fail(); }catch(IllegalArgumentException e) { } }

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  • Pageview implementation

    - by The Elite Gentleman
    Hi everyone I want to add a pageview feature on my current web application. This page view is based on the count of user viewing the page. It must be unique, i.e. I must not view a person's page 10000 times and record it as 10000 views, just record 1 view instead. My question is, should I base my pageview count on IP address? If not, what is/are the best approach in doing this? I know that if the person has logged in to my system, I can simply use the user id stored in the session and check on the record if the user has/hasn't viewed the page and update accordingly. But for "anonymous" viewers, what is the best approach? Thanks. PS How does Youtube does it?

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  • Apache Commons Net FTPClient and listFiles()

    - by Vladimir
    Can anyone explain me what's wrong with the following code? I tried different hosts, FTPClientConfigs, it's properly accessible via firefox/filezilla... FTPClientConfig config = new FTPClientConfig(FTPClientConfig.SYST_L8); FTPClient client = new FTPClient(); client.configure(config); client.connect("c64.rulez.org"); client.login("anonymous", "anonymous"); client.enterRemotePassiveMode(); FTPFile[] files = client.listFiles(); Assert.assertTrue(files.length > 0);

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  • Setting Mnemonics and Hot Keys for a JOptionPane Dialog

    - by Daniel Bingham
    Is it possible to assign hotkeys and mnemonics to the buttons in a JOptionPane Dialog? I'd like to be able, in a JOptionPane generated message dialog with the options Yes, No and Cancel, press Y to hit the Yes button, N to hit the No button and escape to activate the escape button. Similarly in a dialog with Okay and Cancel buttons I'd like to be able to activate them with enter and escape. I've attempted passing JButtons into the JOptionPane's button Object array with the Mnemonics set already. The mnemonics work and the buttons show up correctly in the dialogs, however, they do not act properly when they are activated. Most noticeably they do not dispose of the dialog. What is the correct way to add hotkeys and Mnemonics to a JOptionPane Dialog's buttons? As always, my apologies ahead of time if this is a duplicate - I searched both Google and Stackoverflow and found nothing.

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  • jpa @version optimistic locking

    - by cometta
    I loaded same entity record on 2 separate browser window then press submit (hibernate template.merge), version number incremented for both browser window, but never caught any problem with optimistic lock.. so how to test this? my save() look like this hibernatetemplate().merge(..); setJPAObject(null); //reset after save

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  • Timer Service in ejb 3.1 - schedule calling timeout problem

    - by Greg
    Hi Guys, I have created simple example with @Singleton, @Schedule and @Timeout annotations to try if they would solve my problem. The scenario is this: EJB calls 'check' function every 5 secconds, and if certain conditions are met it will create single action timer that would invoke some long running process in asynchronous fashion. (it's sort of queue implementation type of thing). It then continues to check, but as long as long running process is there it won't start another one. Below is the code I came up with, but this solution does not work, because it looks like asynchronous call I'm making is in fact blocking my @Schedule method. @Singleton @Startup public class GenerationQueue { private Logger logger = Logger.getLogger(GenerationQueue.class.getName()); private List<String> queue = new ArrayList<String>(); private boolean available = true; @Resource TimerService timerService; @Schedule(persistent=true, minute="*", second="*/5", hour="*") public void checkQueueState() { logger.log(Level.INFO,"Queue state check: "+available+" size: "+queue.size()+", "+new Date()); if (available) { timerService.createSingleActionTimer(new Date(), new TimerConfig(null, false)); } } @Timeout private void generateReport(Timer timer) { logger.info("!!--timeout invoked here "+new Date()); available = false; try { Thread.sleep(1000*60*2); // something that lasts for a bit } catch (Exception e) {} available = true; logger.info("New report generation complete"); } What am I missing here or should I try different aproach? Any ideas most welcome :) Testing with Glassfish 3.0.1 latest build - forgot to mention

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  • Easiest way to export longitude and latitude data stored in a SQLite database to a file so it can be

    - by LordSnoutimus
    Hello, I have created an application that records a series of longitude and latitude values in a SQLite database and display them as a coloured track on a MapActivity. I now want to be able to export this data somehow (preferably to a file) so a user can upload the values to a website showing a Google Map API. My question is: what would be the quickest way to export the data (and in what file format: GPX, XML, CSV) to the SD card located on the Android device. Many thanks.

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  • In a bidirectional JPA OneToMany/ManyToOne association, what is meant by "the inverse side of the as

    - by Bytecode Ninja
    In these examples on TopLink JPA Annotation Reference: Example 1-59 @OneToMany - Customer Class With Generics @Entity public class Customer implements Serializable { ... @OneToMany(cascade=ALL, mappedBy="customer") public Set<Order> getOrders() { return orders; } ... } Example 1-60 @ManyToOne - Order Class With Generics @Entity public class Order implements Serializable { ... @ManyToOne @JoinColumn(name="CUST_ID", nullable=false) public Customer getCustomer() { return customer; } ... } It seams to me that the Customer entity is the owner of the association. However, in the explanation for the mappedBy attribute in the same document, it is written that: if the relationship is bidirectional, then set the mappedBy element on the inverse (non-owning) side of the association to the name of the field or property that owns the relationship as Example 1-60 shows. However, if I am not wrong, looks like in the example the mappedBy is actually specified on the owning side of the association, rather than the non-owning side. So my question is basically: In a bidirectional (one-to-many/many-to-one) association, which of the entities is the owner? How can we designate the One side as the owner? How can we designate the Many side as the owner? What is meant by "the inverse side of the association"? How can we designate the One side as the inverse? How can we designate the Many side as the inverse? Thanks in advance.

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  • Can it be done in a more elegant way with the Swing Timer?

    - by Roman
    Bellow is the code for the simplest GUI countdown. Can the same be done in a shorter and more elegant way with the usage of the Swing timer? import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.SwingUtilities; public class CountdownNew { static JLabel label; // Method which defines the appearance of the window. public static void showGUI() { JFrame frame = new JFrame("Simple Countdown"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); label = new JLabel("Some Text"); frame.add(label); frame.pack(); frame.setVisible(true); } // Define a new thread in which the countdown is counting down. public 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() { public void run() { label.setText("You have " + i + " seconds."); } } ); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { showGUI(); counter.start(); } }); } }

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  • ExecutorService memory leak on exception

    - by TofuBeer
    I am having a hard time tracking this down since the profiler keeps crashing (hotspot error). Before I go too deep into figuring it out I'd like to know if I really have a problem or not :-) I have a few thread pools created via: Executors.newFixedThreadPool(10); The threads connect to different web sites and, on occasion, I get connection refused and wind up throwing an exception. When I later on call Future.get() to get the result it will then catch the ExecutionException that wraps the exception that was thrown when the connection could not be made. The program uses a fairly constant amount of memory up until the point in time that the exceptions get thrown (they tend to happen in batches when a particular site is overloaded). After that point the memory again remains constant but at a higher level. So my question is along the lines of is the memory behaviour (reported by "top" on Unix) expected because the exceptions just triggered something or do I probably have an actual leak that I'll need to track down? Additionally when Future.get() throws an exception is there anything else I need to do besides catch the exception (such as call Future.cancel() on it)?

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  • How do i keep my DB and lucene in sync?

    - by acidzombie24
    So i can have a transaction in sql. But i am sure its not a good idea to wait in the middle of a transaction for lucene to finish also i am unsure if lucene is permanently saved in the DB until i do something there. Whats the best way to keep my DB and lucene in sync? I am thinking of adding a lucene_queue in my sql db and everytime i make a change i add it into the queue (removing older queue if any) and delete it once it is done. Is this the best way? Also i am unsure how to make lucene permanently keep the changes i made and how frequent i can/should do it.

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  • Testing REST webservices

    - by anjanb
    HI There, My organization is working on building RESTful webservices on JBoss appserver. The QA team is used to testing SOAP webservices so far using SoapUI. SoapUI has a new version that has REST capabilities. We're considering using that. 1) Are there any publicly available RESTful services available on the net for free that someone could test ? 2) What tools are available(and used) for testing RESTful web services ? Thank you in Advance, BR, ~A

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  • JSF 2.1 Spring 3.0 Integration

    - by danny.lesnik
    I'm trying to make very simple Spring 3 + JSF2.1 integration according to examples I googled in the web. So here is my code: My HTML submitted to actionController.actionSubmitted() method: <h:form> <h:message for="textPanel" style="color:red;" /> <h:panelGrid columns="3" rows="5" id="textPanel"> //all my bean prperties mapped to HTML code. </h:panelGrid> <h:commandButton value="Submit" action="#{actionController.actionSubmitted}" /> </h:form> now the Action Controller itself: @ManagedBean(name="actionController") @SessionScoped public class ActionController implements Serializable{ @ManagedProperty(value="#{user}") User user; @ManagedProperty(value="#{mailService}") MailService mailService; public void setMailService(MailService mailService) { this.mailService = mailService; } public void setUser(User user) { this.user = user; } private static final long serialVersionUID = 1L; public ActionController() {} public String actionSubmitted(){ System.out.println(user.getEmail()); mailService.sendUserMail(user); return "success"; } } Now my bean Spring: public interface MailService { void sendUserMail(User user); } public class MailServiceImpl implements MailService{ @Override public void sendUserMail(User user) { System.out.println("Mail to "+user.getEmail()+" sent." ); } } This is my web.xml <listener> <listener-class> org.springframework.web.context.ContextLoaderListener </listener-class> </listener> <listener> <listener-class> org.springframework.web.context.request.RequestContextListener </listener-class> </listener> <!-- Welcome page --> <welcome-file-list> <welcome-file>index.xhtml</welcome-file> </welcome-file-list> <!-- JSF mapping --> <servlet> <servlet-name>Faces Servlet</servlet-name> <servlet-class>javax.faces.webapp.FacesServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> my applicationContext.xml <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"> <bean id="mailService" class="com.vanilla.jsf.services.MailServiceImpl"> </bean> </beans> my faces-config.xml is the following: <application> <el-resolver> org.springframework.web.jsf.el.SpringBeanFacesELResolver </el-resolver> <message-bundle> com.vanilla.jsf.validators.MyMessages </message-bundle> </application> <managed-bean> <managed-bean-name>actionController</managed-bean-name> <managed-bean-class>com.vanilla.jsf.controllers.ActionController</managed-bean-class> <managed-bean-scope>session</managed-bean-scope> <managed-property> <property-name>mailService</property-name> <value>#{mailService}</value> </managed-property> </managed-bean> <navigation-rule> <from-view-id>index.xhtml</from-view-id> <navigation-case> <from-action>#{actionController.actionSubmitted}</from-action> <from-outcome>success</from-outcome> <to-view-id>submitted.xhtml</to-view-id> <redirect /> </navigation-case> </navigation-rule> My Problem is that I'm getting NullPointerExeption because my mailService Spring bean is null. public String actionSubmitted(){ System.out.println(user.getEmail()); //mailService is null Getting NullPointerException mailService.sendUserMail(user); return "success"; }

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