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  • Is it possible to add JPA annotation to superclass instance variables?

    - by Kristofer Borgstrom
    Hi, I am creating entities that are the same for two different tables. In order do table mappings etc. different for the two entities but only have the rest of the code in one place - an abstract superclass. The best thing would be to be able to annotate generic stuff such as column names (since the will be identical) in the super class but that does not work because JPA annotations are not inherited by child classes. Here is an example: public abstract class MyAbstractEntity { @Column(name="PROPERTY") //This will not be inherited and is therefore useless here protected String property; public String getProperty() { return this.property; } //setters, hashCode, equals etc. methods } Which I would like to inherit and only specify the child-specific stuff, like annotations: @Entity @Table(name="MY_ENTITY_TABLE") public class MyEntity extends MyAbstractEntity { //This will not work since this field does not override the super class field, thus the setters and getters break. @Column(name="PROPERTY") protected String property; } Any ideas or will I have to create fields, getters and setters in the child classes? Thanks, Kris

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  • A[i] * A[j] = k in O(nlog(n))

    - by gleb-pendler
    A is an Array of n positive int numbers k given int Algorithm should find if there is a pair of numbers which product gives the result a. A[i] * A[j] = k b. A[i] = A[j] + k if there is such a couple the algorithm should return thier index. thanks in advance.

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  • How to implement custom JSF component for drawing chart?

    - by Roman
    I want to create a component which can be used like: <mc:chart data="#{bean.data}" width="200" height="300" /> where #{bean.data} returns a collection of some objects or chart model object or something else what can be represented as a chart (to put it simple, let's assume it returns a collection of integers). I want this component to generate html like this: <img src="someimg123.png" width="200" height="300"/> The problem is that I have some method which can receive data and return image, like: public RenderedImage getChartImage (Collection<Integer> data) { ... } and I also have a component for drawing dynamic image: <o:dynamicImage width="200" height="300" data="#{bean.readyChartImage}/> This component generates html just as I need but it's parameter is array of bytes or RenderedImage i.e. it needs method in bean like this: public RenderedImage getReadyChartImage () { ... } So, one approach is to use propertyChangedListener on submit to set data (Collection<Integer>) for drawing chart and then use <o:dynamicImage /> component. But I'd like to create my own component which receives data and draws chart. I'm using facelets but it's not so important indeed. Any ideas how to create the desired component? P.S. One solution I was thinking about is not to use <o:dynamicImage/> and use some servlet to stream image. But I don't know how to implement that correctly and how to tie jsf component with servlet and how to save already built chart images (generating new same image for each request can cause performance problems imho) and so on..

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  • How do I prevent JAXB from binding superclass methods of the @XmlRootElement when marshalling?

    - by Matt Fisher
    I have a class that is annotated as the @XmlRootElement with @XmlAccessorType(XmlAccessType.NONE). The problem that I am having is that the superclass's methods are being bound, when I do not want them to be bound, and cannot update the class. I am hoping there is an annotation that I can put on the root element class to prevent this from happening. Example: @XmlRootElement @XmlAccessorType(XmlAccessType.NONE) public class Person extends NamedObject { @XmlElement public String getId() { ... } } I would expect that only the methods annotated @XmlElement on Person would be bound and marshalled, but the superclass's methods are all being bound, as well. The resulting XML then has too much information. How do I prevent the superclass's methods from being bound without having to annotate the superclass, itself?

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  • Is it OK to reference 'this' when initializing a field?

    - by parxier
    Is it OK to reference this when initializing a field? public class MainClass { private SomeFieldClass field = new SomeFieldClass(this); public MainClass() {} } Or is it better to do that in constructor? public class MainClass { private SomeFieldClass field; public MainClass() { this.field = new SomeFieldClass(this); } } What is the best practice? I believe first option is better for unit testing and dependency injection. Are there any problems with it?

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  • How do I correctly decode unicode parameters passed to a servlet

    - by Grant Wagner
    Suppose I have: <a href="http://www.yahoo.com/" target="_yahoo" title="Yahoo!&#8482;" onclick="return gateway(this);">Yahoo!</a> <script type="text/javascript"> function gateway(lnk) { window.open(SERVLET + '?external_link=' + encodeURIComponent(lnk.href) + '&external_target=' + encodeURIComponent(lnk.target) + '&external_title=' + encodeURIComponent(lnk.title)); return false; } </script> I have confirmed external_title gets encoded as Yahoo!%E2%84%A2 and passed to SERVLET. If in SERVLET I do: Writer writer = response.getWriter(); writer.write(request.getParameter("external_title")); I get Yahoo!â„¢ in the browser. If I manually switch the browser character encoding to UTF-8, it changes to Yahoo!TM (which is what I want). So I figured the encoding I was sending to the browser was wrong (it was Content-type: text/html; charset=ISO-8859-1). I changed SERVLET to: response.setContentType("text/html; charset=utf-8"); Writer writer = response.getWriter(); writer.write(request.getParameter("external_title")); Now the browser character encoding is UTF-8, but it outputs Yahoo!â?¢ and I can't get the browser to render the correct character at all. My question is: is there some combination of Content-type and/or new String(request.getParameter("external_title").getBytes(), "UTF-8"); and/or something else that will result in Yahoo!TM appearing in the SERVLET output?

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  • J2ME TextField Exception

    - by Bob
    When I instantiate a textField, I have a number in it that I want to be the default text. The problem is, I can't seem to be able to place that value into the textfield without getting an error. The strange thing about it is that the same TextField is what I use to set the value of the variable containing the number. TextField myTF = new TextField("Number", value, 10, TextField.NUMERIC); When I run this code, I receive an exception stating that value doesn't match the constraints of TextField.NUMERIC. However, when I check the vale of the value of the variable, I get the following output: value = 1234567890 value.length() = 10 The value is set by the same TextField, saved to the phone that I am working on, and when loaded from the phone's settings, throws an exception.

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  • Can I fix the width of JRadioButton?

    - by Roman
    I have sever JPanels which have to be ordered vertically. For that I want to fix the width of the JPanels. Because if they are too short in comparison with the windows width, they will go horizontally (one after another) and I do not want it. At the moment the width of the JPanel is not constant because the width of the JRadioButton (included into JPabel) is not constant. How can I make the width of the JRadioButton constant? At the moment it is not constant because of the label (which can be different).

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  • How can I create a user registration form using datastore - google appengine ??

    - by srivigneshwar
    I am very new to jsp and google appengine , but still I can do something if I get some basic idea , I wanna create an user registration form with fields like name, user id , password, confirm password, etc,. using google appengine datastore feature. and I wanna retrieve user information . Please help me .. Thanks in advance. Thanks for the replies, I need to get some information from user and I want to store it in database, and I will use that information for my application. How can I do that?

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  • Pause and resume thread drawing to SurfaceView

    - by fhucho
    I am developing a chess game for Android (http://androidchess.appspot.com), using SurfaceView for the chessboard. I have a drawing Thread, that draws the chessboard in a loop. The problem is that when there are no active animations (this is more that 90% of time), it makes no sense to waste CPU and battery for drawing. How should I solve this? Maybe somehow pausing and resuming the drawing Thread?

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  • Show/hide views with checkbox

    - by DixieFlatline
    Hi! I want to show or hide some elements (textviews and edittexts) with checkbox. I set their visibility to gone in layout file. Showing them when user checks the box works, but the when user unchecks it, they don't hide. (android 1.5 and 1.6) My code: cb=(CheckBox)findViewById(R.id.cek); cb.setOnClickListener(new OnClickListener() { // checkbox listener public void onClick(View v) { // Perform action on clicks, depending on whether it's now checked if (((CheckBox) v).isChecked()) { tv1.setVisibility(0); //visible==0 et3.setVisibility(0); } else if (((CheckBox) v).isChecked() == false) { tv1.setVisibility(2); //gone=2 et3.setVisibility(2); } } });

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  • How can I get the size?

    - by Sanju
    I got a class. Lets say its named Class1 Here I create another class, Class2 Class2 has an arrya[] No my question is. When I create Class2 I cant have any size of the array with me in. How can I then know how big I want the array to be??? Out in Class1 I know how big it is. Thanks in Advance.

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  • check if a tree is a binary search tree

    - by TimeToCodeTheRoad
    I have written the following code to check if a tree is a Binary search tree. Please help me check the code: Pair p{ boolean isTrue; int min; int max; } public boo lean isBst(BNode v){ return isBST1(v).isTrue; } public Pair isBST1(BNode v){ if(v==null) return new Pair(true, INTEGER.MIN,INTEGER.MAX); if(v.left==null && v.right==null) return new Pair(true, v.data, v.data); Pair pLeft=isBST1(v.left); Pair pRight=isBST1(v.right); boolean check=pLeft.max<v.data && v.data<= pRight.min; Pair p=new Pair(); p.isTrue=check&&pLeft.isTrue&&pRight.isTrue; p.min=pLeft.min; p.max=pRight.max; return p; } Note: This function checks if a tree is a binary search tree

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  • How to detect a pending JDO transaction?

    - by Stevko
    I believe I am getting JDO commit Exceptions due to the transactions nesting although I'm not sure. Will this detect the situation where I am starting a transaction when another is pending? PersistenceManager pm = PersistenceManagerFactory.get().getPersistenceManager(); assert pm.currentTransaction().isActive() == false : "arrrgh"; pm.currentTransaction().begin(); Is there a better or more reliable way?

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  • Putting Select Statement on Hibernate Transaction

    - by Mark Estrada
    Hi All, I have been reading the net for a while regarding Hibernate but I can seem to understand one concept regarding Transaction. On some site that I have visit, Select statements are in transaction mode like this. public List<Book> readAll() { Session session = HibernateUtil.getSessionFactory() .getCurrentSession(); session.beginTransaction(); List<Book> booksList = session.createQuery("from Book").list(); session.getTransaction().commit(); return booksList; } While on some site, it does not advocate the use of transaction on Select statements public List<Book> readAll() { Session session = HibernateUtil.getSessionFactory() .getCurrentSession(); List<Book> booksList = session.createQuery("from Book").list(); return booksList; } I am thinking which one should I follow. Any thoughts please? Are transactions needed on Select Statements or not? Thanks

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  • Closing Connections on asynchronous messaging in JMS

    - by The Elite Gentleman
    Hi Everyone! I have created a JMS wrapper (similar to Springs JmsTemplate since I'm not using Springs) and I was wondering: If I setup asynchronous messaging, when is a good time to close connections and JMS relates resources (so that the Connection Factory in the Resource Pool can be available)? Thanks Here's the source code for receiving JMS messages public Message receive() throws JMSException { QueueConnection connection = null; QueueSession session = null; QueueReceiver consumer = null; try { // TODO Auto-generated method stub connection = factory.createQueueConnection(); if (connection != null && getExceptionListener() != null) { connection.setExceptionListener(getExceptionListener()); } session = connection.createQueueSession(isSessionTransacted(), getAcknowledgeMode()); consumer = session.createReceiver(queue); if (getMessageListener() != null) { consumer.setMessageListener(getMessageListener()); } //Begin connection.start(); if (getMessageListener() == null) { return null; } return receive(session, consumer); } catch (JMSException e) { // TODO: handle exception logger.error(e.getLocalizedMessage(), e); throw e; } finally { JMSUtil.closeMessageConsumer(consumer); JMSUtil.closeSession(session, false); //false = don't commit. JMSUtil.closeConnection(connection, true); //true = stop before close. } As you can see, if getMessageListener() != null then apply it to the MessageConsumer. Am I doing this correctly? The same approach has also been taken for JMS Topic.

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  • How to replace a regexp group with a post proceed value?

    - by Pentium10
    I have this code to public static String ProcessTemplateInput(String input, int count) { Pattern pattern = Pattern.compile("\\{([^\\}]+)\\}"); Matcher matcher = pattern.matcher(input); while (matcher.find()) { String newelem=SelectRandomFromTemplate(matcher.group(1), count); } return input; } Input is: String s1 = "planets {Sun|Mercury|Venus|Earth|Mars|Jupiter|Saturn|Uranus|Neptune}{?|!|.} Is this ok? "; Output example: String s2="planets Sun, Mercury. Is this ok? "; I would like to replace the {} set of templates with the picked value returned by the method. How do I do that in Java1.5?

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  • How can I find out if two arguments are instances of the same, but unknown class?

    - by Ingmar
    Let us say we have a method which accepts two arguments o1 and o2 of type Object and returns a boolean value. I want this method to return true only when the arguments are instances of the same class, e.g.: foo(new Integer(4),new Integer(5)); Should return true, however: foo(new SomeClass(), new SubtypeSomeClass()); should return false and also: foo(new Integer(3),"zoo"); should return false. I believe one way is to compare the fully qualified class names: public boolean foo(Object o1, Object o2){ Class<? extends Object> c1 = o1.getClass(); Class<? extends Object> c2 = o2.getClass(); if(c1.getName().equals(c2.getName()){ return true;} return false; } An alternative conditional statement would be : if (c1.isAssignableFrom(c2) && c2.isAssignableFrom(c1)){ return true; } The latter alternative is rather slow. Are there other alternatives to this problem?

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  • Application Server or Lightweight Container?

    - by Jeff Storey
    Let me preface this by saying this is not an actual situation of mine but I'm asking this question more for my own knowledge and to get other people's inputs here. I've used both Spring and EJB3/JBoss, and for the smaller types of applications I've built, Spring (+Tomcat when needed) has been much simpler to use. However, when scaling up to larger applications that require things like load balancing and clustering, is Spring still a viable solution? Or is it time to turn to a solution like EJB3/JBoss when you start to get big enough to need that? I'm not sure if I've scoped the problem well enough to get a good answer, so please let me know. Thanks, Jeff

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  • Using UNINSTALL_SHORTCUT Intent

    - by Lucas S.
    I am trying to use the following intent action, but i get an ActivityNotFoundException in the fisrt case. And nothing at all in the second case. "com.android.launcher.action.UNINSTALL_SHORTCUT" I try to use it with the following code: Intent i = new Intent ("com.android.launcher.action.UNINSTALL_SHORTCUT"); startActivity(i); Also with the following: Intent i = new Intent ("com.android.launcher.action.UNINSTALL_SHORTCUT"); sendBroadCast(i);

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  • Using ControllerClassNameHandlerMapping with @Controller and extending AbstractController

    - by whiskerz
    Hey there, actually I thought I was trying something really simple. ControllerClassNameHandlerMapping sounded great to produce a small spring webapp using a very lean configuration. Just annotate the Controller with @Controller, have it extend AbstractController and the configuration shouldn't need more than this <context:component-scan base-package="test.mypackage.controller" /> <bean id="urlMapping" class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping" /> to resolve my requests and map them to my controllers. I've mapped the servlet to "*.spring", and calling <approot>/hello.spring All I ever get is an error stating that no mapping was found. If however I extend the MultiActionController, and do something like <approot>/hello/hello.spring it works. Which somehow irritates me, as I would have thought that if that is working, why didn't my first try? Does anyone have any idea? The two controllers I used looked like this @Controller public class HelloController extends AbstractController { @Override protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response) throws Exception { ModelAndView modelAndView = new ModelAndView("hello"); modelAndView.addObject("message", "Hello World!"); return modelAndView; } } and @Controller public class HelloController extends MultiActionController { public ModelAndView hello(HttpServletRequest request, HttpServletResponse response) throws Exception { ModelAndView modelAndView = new ModelAndView("hello"); modelAndView.addObject("message", "Hello World!"); return modelAndView; } }

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