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  • Problem with extending JPanel

    - by Halo
    I have an abstract entity: public abstract class Entity extends JPanel implements FocusListener And I have a TextEntity: public class TextEntity extends Entity Inside TextEntity's constructor I want to put a JTextArea that will cover the panel: textArea = new JTextArea(); textArea.setSize(getWidth(),getHeight()); add(textArea); But getWidth() and getHeight() returns 0. Is it a problem with the inheritance or the constructor?

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  • How does the event dispatch thread work?

    - by Roman
    With the help of people on stackoverflow I was able to get the following working code of the simples GUI countdown (it just displays a window counting down seconds). My main problem with this code is the invokeLater stuff. As far as I understand the invokeLater send a task to the event dispatching thread (EDT) and then the EDT execute this task whenever it "can" (whatever it means). Is it right? To my understanding the code works like that: In the main method we use invokeLater to show the window (showGUI method). In other words, the code displaying the window will be executed in the EDT. In the main method we also start the counter and the counter (by construction) is executed in another thread (so it is not in the event dispatching thread). Right? The counter is executed in a separate thread and periodically it calls updateGUI. The updateGUI is supposed to update GUI. And GUI is working in the EDT. So, updateGUI should also be executed in the EDT. It is why the code for the updateGUI is inclosed in the invokeLater. Is it right? What is not clear to me is why we call the counter from the EDT. Anyway it is not executed in the EDT. It starts immediately a new thread and the counter is executed there. So, why we cannot call the counter in the main method after the invokeLater block? 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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  • Caching instances in a jee web app

    - by SibzTer
    Hi, Consider the scenario of a typical webapp with JSFs on the front and ejb3, with Hibernate as JPA provider, talking to backend database such as mysql, etc. The main user actions are login and mostly CRUD operations (minus any D(elete) operations). And the App Server is GlassFish of course. Given this scenario, how and where all would one go about providing caching to improve performance? From what I have googled, I have seen that hibernate provides some sort of caching through different cache providers. Is there any sort of caching that can be provided for the jsf pages? How about session beans or entity beans on the ejb side of things? Also, I just read about memcached and was wondering if this was something to consider?

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  • How can you tell if an activities state is stored?

    - by Joren
    I have an activity which pulls some JSON from my server, and then uses it to draw a list. That list launches further activities. My problem is that I can't figure out a way to tell if the activity is still alive when you go back to it, so I end up re-querying my JSON from the server and redrawing the list every time the user goes back to the activity. How can I tell if my activity is still alive so I can skip the redraw?

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  • Why are static imports of static methods with same names legal?

    - by user1055638
    Lets say we have these packages and classes: package p1; public class A1 { public static void a() {} } package p2; public class A1 { public static void a() {} } package p3; import static p1.A1.a; import static p2.A1.a; public class A1 { public static void test() { } } I am wondering, why the static import of methods is legal (won't result in compile time error) in package p3? We won't be able to use them further in the test() method as such usage will result in the compile time error. Why it is not the same as with a normal import of classes. Lets say we would like to import classes A1 from packages p1 and p2 into p3: package p3; import p1.A1; import p2.A1; such import is illegal and will result in the compile time error.

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  • [hibernate - jpa] @OneToOne annotoation problem (i think...)

    - by blow
    Hi all, im new in hibernate and JPA and i have some problems with annotations. My target is to create this table in db (PERSON_TABLE with personal-details) ID ADDRESS NAME SURNAME MUNICIPALITY_ID First of all, i have a MUNICIPALITY table in db containing all municipality of my country. I mapped this table in this ENTITY: @Entity public class Municipality implements Serializable { @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private Long id; private String country; private String province; private String name; @Column(name="cod_catasto") private String codCatastale; private String cap; public Municipality() { } ... Then i make an EMBEDDABLE class Address containing fields that realize a simple address... @Embeddable public class Address implements Serializable { @OneToOne(cascade=CascadeType.ALL) @JoinColumn(name="id_municipality") private Municipality municipality; @Column(length=45) private String address; public Address() { } ... Finally i embedded this class into Person ENTITY @Entity public class Person implements Serializable { @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private Long id; private String name; private String surname; @Embedded private Address address; public Person() { } ... All works good when i have to save a new Person record, in fact hibernate creates a PERSON_TABLE as i want, but if i try to retrieve a Person record i have an exception. HQL is simply "from Person" The excpetion is (Entities is the package containing all classes above-mentioned): org.hibernate.AnnotationException: @OneToOne or @ManyToOne on Entities.Person.address.municipality references an unknown entity: Entities.Municipality Is the @OneToOne annotation the problem? Thanks.

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  • Sad logic on types

    - by user2972231
    Code base is littered with code like this: BaseRecord record = // some BaseRecord switch(record.source()) { case FOO: return process((FooRecord)record); case BAR: return process((BarRecord)record); case QUUX: return process((QuuxRecord)record); . . // ~25 more cases . } and then private SomeClass process(BarRecord record) { } private SomeClass process(FooRecord record) { } private SomeClass process(QuuxRecord record) { } It makes me terribly sad. Then, every time a new class is derived from BaseRecord, we have to chase all over our code base updating these case statements and adding new process methods. This kind of logic is repeated everywhere, I think too many to add a method for each and override in the classes. How can I improve this?

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  • list or container O(1)-ish insertion/deletion performance, with array semantics

    - by Chris Kaminski
    I'm looking for a collection that offers list semantics, but also allows array semantics. Say I have a list with the following items: apple orange carrot pear then my container array would: container[0] == apple container[1] == orangle container[2] == carrot Then say I delete the orange element: container[0] == apple container[1] == carrot I don't particularly care if sort order is maintained, I'd just like the array values to function as accelerators to the list items, and I want to collapse gaps in the array without having to do an explicit resizing.

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  • Hibernate/JPA - annotating bean methods vs fields

    - by Benju
    I have a simple question about usage of Hibernate. I keep seeing people using JPA annotations in one of two ways by annotating the fields of a class and also by annotating the get method on the corresponding beans. My question is as follows: Is there a difference between annotating fields and bean methods with JPA annoations such as @Id. example: @Entity public class User { **@ID** private int id; public int getId(){ return this.id; } public void setId(int id){ this.id=id; } } -----------OR----------- @Entity public class User { private int id; **@ID** public int getId(){ return this.id; } public void setId(int id){ this.id=id; } }

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  • how to remove ConcurrentModificationException

    - by maverick
    what is this exception and how to remove this in my problem i am creating an arraylist of objects, and after checking some condition,i want to remove some objects. but the program is giving this exception ConcurrentModificationException. how to remove this thanks in advance

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  • Hibernate: how to maintain insertion order

    - by jwaddell
    I have a list of entities where creation order is important, but they do not contain a timestamp to use for sorting. Entities are added to the end of the list as they are created so they will be ordered correctly in the list itself. After persisting the list using Hibernate the entities appear in the database table in the order that they were created. However when retrieving the list using a new Hibernate session the list is now in reverse order of insertion/creation. Is this expected behaviour? Is there any way to retrieve the list in the same order as it appears in the table? The primary key is a UUID, and the list of entities should always have been created on the same IP address and JVM. This mean sorting by UUID is a possibility but I'd rather not make assumptions. Another possibility is if the list is guaranteed to always come out in reverse order I could always just work through it backwards.

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  • vlcj not displaying the video

    - by Cássio Eudardo
    I'm using vlcj to play video, but the video doesn't display on some computers(i tested in 4 and worked on 2, all windows), on 1 it displays the button but not the video and on the other it just display a gray background without the button. I tested .wmv and .avi files. I'm using the following code: public class Video extends JFrame implements WindowListener{ private JPanel contentPane; private JButton btnClose; private Dimension size; private float aspectRatio; private EmbeddedMediaPlayer mediaPlayer; public Video() { try { size = Toolkit.getDefaultToolkit().getScreenSize(); aspectRatio = (float)size.width/size.height; String file = "..."; btnClose = new JButton("X"); btnClose.addActionListener(new ActionListener() {...}); btnClose.setBounds(640 - 50, 10, 40, 40); setBounds(size.width/2 - 320, (int)(size.height - 40*aspectRatio) - 250, 640, 200); contentPane = new JPanel(); contentPane.setLayout(null); setContentPane(contentPane); WindowsCanvas surface = new WindowsCanvas(); contentPane.setBounds(0, 0, 640, 200); surface.setBounds(0, 0, 640, 200); MediaPlayerFactory factory = new MediaPlayerFactory(new String("--no-video-title-show")); mediaPlayer = factory.newEmbeddedMediaPlayer(); surface.addMouseListener(new MouseListener() {...}); contentPane.add(btnClose); contentPane.add(surface); setVisible(true); mediaPlayer.setVideoSurface(factory.newVideoSurface(surface)); mediaPlayer.setRepeat(true); mediaPlayer.playMedia(file); } catch(Exception e) { } }}

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  • Is System.nanoTime() consistent across threads?

    - by obvio171
    I want to count the time elapsed between two events in nanoseconds. To do that, I can use System.nanoTime() as mentioned here. The problem is that the two events are happening in different threads. Since nanoTime() doesn't return an absolute timestamp but instead can only be used to calculate time differences, I'd like to know if the values I get on the two different threads are consistent with the physical time elapsed between the two events.

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  • Dynamically create and cast objects at runtime

    - by vaibhav bindroo
    Let's say we have 2 classes A and B public class A{ private int member1; A() { member1 = 10; } public getMember(){ return member1; } } Class B is also on the same lines except that its member variable is named member2 and gets intitialized to say 20 inside the constructor. My Requirement : At runtime , I get a string which contains a className ( could be A or B). I want to dynamically create an object of this class along with invoking the constructor. How can I achieve this . I don't want to use interfaces for common functionality of above classes Morever, later on I set the properties of this raw object using Propery Builder Bean Util class based on a list of columns . Class clazz = Class.forName("className"); Obj obj = clazz.newInstance(); How I can dynamically convert that obj to className object.

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  • OSGI, Servlets and JPA hello world / tutorial / example

    - by Kamil
    I want to build a web application which basically is a restful web-service serving json messages. I would like it to be as simple as possible. I was thinking about using servlets (with annotations). JPA as a database layer is a must - Toplink or Hibernate. Preferably working on Tomcat. I want to have app divided into modules serving different functionality (auth service, customer service, etc..). And I would like to be able to update those modules without reinstalling whole application on the server - like eclipse plugins, user is notified (when he enters webapp's home url) that update is available, clicks it, and app is downloading and installing updated module. I think this functionality can be made with OSGI, but I can't find any example code, or tutorial with simple hello world updatable servlet providing some data from database through jpa. I'm looking for an advice: - Is OSGI the right tool for this or it can be done with something simpler? - Where can I find some examples covering topic (or topics) which I need for this project. - Which OSGI implementation would be best-simplest for this task. *My knowledge of OSGI is basic. I know how bundles are described, I understand concept of OSGI container and what it does. I have never created any OSGI app yet.

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  • DYNAMICALLY CHANGE JCOMBOBOX

    - by Suman.hassan95
    i am fetching the data values from the database success fully. I have also stored them into a String array. I need to load the String array as the items of the ComboBox in response to key actionperformed . How can i reload the items of the ComboBox whenever a key is pressed as the fetched values depend on the key pressed. Rather simply, i need to dynamically refresh the ComboBox items. please help.

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  • Create a buffered image from rgb pixel values

    - by Jeff Storey
    I have an integer array of RGB pixels that looks something like: pixels[0] = <rgb-value of pixel(0,0)> pixels[1] = <rgb-value of pixel(1,0)> pixels[2] = <rgb-value of pixel(2,0)> pixels[3] = <rgb-value of pixel(0,1)> ...etc... And I'm trying to create a BufferedImage from it. I tried the following: BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); img.getRaster().setPixels(0, 0, width, height, pixels); But the resulting image has problems with the color bands. The image is unclear and there are diagonal and horizontal lines through it. What is the proper way to initialize the image with the rgb values? thanks, Jeff

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  • recommendations for firestorm dao replacement

    - by Casey
    I have taken over some code that has been using the Firestorm DAO code generator from CodeFutures. I believe that the license for this is going to be up soon, and was wondering if anyone could recommend any alternatives, open source or not, so that I can get an idea of what's out there to better make a decision.

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  • paintComponent on JPanel, image flashes and then disappears

    - by mark
    I have a JApplet (MainClass extends JApplet), a JPanel (ChartWindow extends JPanel) and a Grafico class. The problem is that the Grafico class instance has 2 JPanel that should show 2 images (1 for each panel) but the images are shown and after a little while they disappears: instead of them i get a gray background (like an empty JPanel). This happens for every repaint() call (that are made in the ChartWindow class) the MainClass init() contains chartwindow=new ChartWindow(); add(chartwindow) chartwindow has a Grafico instance. it's the ChartWindow's paintComponent (override) paintComponent(Graphics g) { super.paintComponent(g); Image immagineGrafico=createImage(grafico.pannelloGrafico.getWidth() ,grafico.pannelloGrafico.getHeight()); Image immagineVolumi=createImage(grafico.pannelloVolumi.getWidth() ,grafico.pannelloVolumi.getHeight()); Graphics2D imgGrafico=(Graphics2D)immagineGrafico.getGraphics(); Graphics2D imgVolumi=(Graphics2D)immagineVolumi.getGraphics(); grafico.draw(imgGrafico,imgVolumi,mouseX,mouseY); ((Graphics2D)grafico.pannelloGrafico.getGraphics()).drawImage(immagineGrafico,0,0,this); ((Graphics2D)grafico.pannelloVolumi.getGraphics()).drawImage(immagineVolumi,0,0,this); } grafico's JPanels are added this way in the ChartWindow's constructor grafico=new Grafico() ................ add(grafico.pannelloGrafico); add(grafico.pannelloVolumi); Tell me if you need more information, thank you very much :-)

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