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  • How to handle JPA annotations for a pointer to a generic interface

    - by HDave
    I have a generic class that is also a mapped super class that has a private field that holds a pointer to another object of the same type: @MappedSuperclass public abstract class MyClass<T extends MyIfc<T>> implements MyIfc<T> { @OneToOne() @JoinColumn(name = "previous", nullable = true) private T previous; ... } My problem is that Eclipse is showing an error in the file at the OneToOne "Target Entity "T" for previous is not an Entity." All of the implementations of MyIfc are, in fact, Entities. I should also add that each concrete implementation that inherit from MyClass uses a different value for T (because T is itself) so I can't use the "targetEntity" attribute. I guess if there is no answer then I'll have to move this JPA annotation to all the concrete subclasses of MyClass. It just seems like JPA/Hibernate should be smart enough to know it'll all work out at run-time. Makes me wonder if I should just ignore this error somehow.

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  • What should be done first: Code reviews or Unit tests?

    - by goldenmean
    Hello, If a developer implements code for some module and wants to get it reviewed. What should be the order : *First unit test the module after designing test cases for the module, debugging and fixing the bugs and then give the modified code for peer code review (Pros- Code to be reviewed is 'clean' to a good extent. Reduces some avoidable review comments and rework. Cons- Developer might spend large time debugging/fixing a bug which could have pointed/anticipated in peer code reviews) Or *First do the code review with peers and then go for unit testing. What are your thoughts/experience on this? I believe this approach for unit testing, code reviewing should be programming language agnostic, but it would be interesting to know otherwise(if applicable) with specific examples. -AD

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  • Eclipse RCP : make a standalone plugin extending an existing standalone one

    - by akira2x3x
    I have extended via extension point (add menus and functionnalities) an already existing plugin which has it's own product definition file and it's own class Application implements IApplication. I want to create a Product Configuration(customize splash screen,etc...). Does my plugin need an Application class? I want my plugin to be independant, Standalone with a launcher. Not a fragment. Do I have to inherit already existing plugin Application? Thanks for the tips and tricks.

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  • get static initialization block to run in a java without loading the class

    - by TP
    I have a few classes as shown here public class TrueFalseQuestion implements Question{ static{ QuestionFactory.registerType("TrueFalse", "Question"); } public TrueFalseQuestion(){} } ... public class QuestionFactory { static final HashMap<String, String > map = new HashMap<String,String>(); public static void registerType(String questionName, String ques ) { map.put(questionName, ques); } } public class FactoryTester { public static void main(String[] args) { System.out.println(QuestionFactory.map.size()); // This prints 0. I want it to print 1 } } How can I change TrueFalseQuestion Type so that the static method is always run so that I get 1 instead of 0 when I run my main method? I do not want any change in the main method. I am actually trying to implement the factory patterns where the subclasses register with the factory but i have simplified the code for this question.

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  • Android; Confused by views?

    - by javano
    I have created a class (InputControl) which extends the view of my main class (Main), and takes focus of the screen. I have a button on the main xml layout which calls control() and sets up my InputControl view, from there I capture user input. How can I return back to the xml layout from the InputControl view class? public class Main extends Activity { public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); InputControl = new InputControl(this); } //......SNIP! public void control(){ setContentView(InputControl); InputControl.requestFocus(); } } public class InputControl extends View implements OnTouchListener { public InputControl(Context context) { super(context); setFocusable(true); setFocusableInTouchMode(true); this.setOnTouchListener(this); } public boolean onTouch(View view, MotionEvent event) { //...I AM CAPTURING USER TOUCH EVENTS HERE } }

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  • Haskell FlatMap

    - by mvid
    I am a beginner interested in Haskell, and I have been trying to implement the flatmap (=) on my own to better understand it. Currently I have flatmap :: (t -> a) -> [t] -> [a] flatmap _ [] = [] flatmap f (x:xs) = f x : flatmap f xs which implements the "map" part but not the "flat". Most of the modifications I make result in the disheartening and fairly informationless Occurs check: cannot construct the infinite type: a = [a] When generalising the type(s) for `flatmap' error. What am I missing?

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  • Memory leak with WPF & ItemsControl (VB.NET)

    - by Matt H.
    I have an ItemsControl that uses a DataTemplate to display properties in my customClass that implements INotifyPropertyChanged... Pretty straightforward... Some items in the DataTemplate use CommandBindings (such as buttons), and a few have some code-behind (yuck). When I empty the ItemsControl and set all instances of customClass = Nothing , no memory is released from my program. This becomes a problem pretty quickly! Any idea where I should start looking? I've even gone so far as to completely traverse the visual tree of each DataTemplate instance and set each Visual = Nothing. I'm not really if that's supposed to have any effect though.

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  • Java singleton VO class implementing serializable, having default values using getter methods

    - by user309281
    Hi All I have a J2SE application having user threads running in a separate JVM outside JBOSS server. During startup, J2SE invokes a EJB inside jboss, by passing a new object(singleton) of simple JAVA VO class having getter/setter methods. {The VO class is a singleton and implements serialiable(as mandated by EJB)}. EJB receives the object, reads all db configuration and uses the setter methods of new object to set all the values. It then returns back this updated object back to J2SE in the same remote call. After J2SE receives the object(singleton/serializable), if i invoke getter methods, I could see only default values set during object creation before EJB call, and not the values set by the EJB. Kindly throw some light on, why the received object from EJB does not see any updated values and how to rectify this. I believe it got to do with object initialization during deserialization. And i tried overriding readResolve() in the VO class, but of no help. With Regards, Krishna

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  • Making your class an event source in Java

    - by Crystal
    I'm making a custom button in Java that has two states, mousePressed, and mouseReleased. At the same time, if I wanted to reuse this button, so that other event listeners can register with it, are these the appropriate steps I should do: override addActionListener(ActionListener action) override removeActionListener(ActionListener action) have a private variable like List <ActionListener> list = new List <ActionListener>() to keep track of when events get added and some sort of function with for loop to run all the actions: public void runListeners() { for (ActionListener al : list) { al.actionPerfomed; } } I'm not really sure if this is the way you can do it or if there are other things I am missing. Like does my custom class have to be implements ActionListener? Thanks.

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  • ItemsControl that loads items one by one asynchronously.

    - by Vinit Sankhe
    Hey Guys, I am creating a custom DataGrid by deriving the traditional tookit based WPF DataGrid. I want a functionality in the grid to load items one by one asynchronously, wherein as soon as ItemsSource is changed i.e. a new collection is Set to the ItemsSource property or the bound collection is Changed dues to items that rae added, moved or removed (wherein the notifications comes to the data grid when the underlying source implements INotifyCollectionChanged such as ObservableCollection). This is because even with virtualising stackpanel underneath the datagrid takes time to load (2-3 seconds delay) to load the data rows when it has several columns and some are template based. With above behavior that delay would "appear" to have reduced giving datagrid a feel that it has the data and is responsive enough to load it. How can I achieve it? Thx Vinit.

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  • richfaces keepAlive not working

    - by Jurgen H
    I have a mediaOutput tag which, in its createContent attribute, requires the backing bean to be in a certain state. A list of values, which is filled in an init method, must be available. I therefore added a keepAlive tag for the whole backing bean. I now indeed see the backingBean in stead of some (richfaces) proxy bean, but the filled list is null again. How to make this possible? I checked that the init method was called and that the list is filled in in the init method. <a4j:keepAlive beanName="myBean" /> <a4j:mediaOutput createContent="#{myBean.writeChart}" ... /> The backing bean public class MyBean implements Serializable { public List list; public void init(ActionEvent event) { // call some resource to fill the list list = service.getItems(); } public void writeChart(final OutputStream out, final Object data) throws IOException { // list is null } // getters & setters }

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  • Storm Trident 'average aggregator

    - by E Shindler
    I am a newbie to Trident and I'm looking to create an 'Average' aggregator similar to 'Sum(), but for 'Average'.The following does not work: public class Average implements CombinerAggregator<Long>.......{ public Long init(TridentTuple tuple) { (Long)tuple.getValue(0); } public Long Combine(long val1,long val2){ return val1+val2/2; } public Long zero(){ return 0L; } } It may not be exactly syntactically correct, but that's the idea. Please help if you can. Given 2 tuples with values [2,4,1] and [2,2,5] and fields 'a','b' and 'c' and doing an average on field 'b' should return '3'. I'm not entirely sure how init() and zero() work. Thank you so much for your help in advance. Eli

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  • Separation of interfaces and implementation

    - by bonefisher
    From assembly(or module) perspective, what do you think of separation of Interface (1.assembly) and its Implementation (2.assembly)? In this way we can use some IoC container to develop more decoupling desing.. Say we have an assembly 'A', which contains interfaces only. Then we have an assembly 'B' which references 'A' and implements those interfaces..It is dependent only on 'A'. In assembly 'C' then we can use the IoC container to create objects of 'A' using dependency injection of objects from 'B'. This way 'B' and 'C' are completely unaware (not dependent) of themselves..

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  • Java HashSet is allowing dupes; problem with comparable?

    - by IVR Avenger
    Hi, all. I've got a class, "Accumulator", that implements the Comparable compareTo method, and I'm trying to put these objects into a HashSet. When I add() to the HashSet, I don't see any activity in my compareTo method in the debugger, regardless of where I set my breakpoints. Additionally, when I'm done with the add()s, I see several duplicates within the Set. What am I screwing up, here; why is it not Comparing, and therefore, allowing the dupes? Thanks, IVR Avenger

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  • Good coding style to do case-select in XSLT

    - by Scud
    I want to have a page display A,B,C,D depending on the return value from XML value (1,2,3,4). My approaches are by javascript or XSLT:choose. I want to know which way is better, and why? Can I do this case-select in .cs code (good or bad)? Should I javascript code in XSLT? Can the community please advise? Thanks. Below are the code. Javascript way (this one works): <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:msxsl="urn:schemas-microsoft-com:xslt" xmlns:js="urn:custom-javascript"> <xsl:template match="page"> <msxsl:script language="JavaScript" implements-prefix="js"> <![CDATA[ function translateSkillLevel(level) { switch (level) { case 0: return "Level 1"; case 1: return "Level 2"; case 2: return "Level 3"; } return "unknown"; } ]]> </msxsl:script> <div id="skill"> <table border="0" cellpadding="1" cellspacing="1"> <tr> <th>Level</th> </tr> <xsl:for-each select="/page/Skill"> <tr> <td> <!-- difference here --> <script type="text/javascript"> document.write(translateSkillLevel(<xsl:value-of select="@level"/>)); </script> </td> </tr> </xsl:for-each> </table> </div> </xsl:template> </xsl:stylesheet> Javascript way (this one doesn't work, getting undefined js tag): <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:msxsl="urn:schemas-microsoft-com:xslt" xmlns:js="urn:custom-javascript"> <xsl:template match="page"> <msxsl:script language="JavaScript" implements-prefix="js"> <![CDATA[ function translateSkillLevel(level) { switch (level) { case 0: return "Level 1"; case 1: return "Level 2"; case 2: return "Level 3"; } return "unknown"; } ]]> </msxsl:script> <div id="skill"> <table border="0" cellpadding="1" cellspacing="1"> <tr> <th>Level</th> </tr> <xsl:for-each select="/page/Skill"> <tr> <td> <!-- difference here --> <xsl:value-of select="js:translateSkillLevel(string(@level))"/> </td> </tr> </xsl:for-each> </table> </div> </xsl:template> </xsl:stylesheet> XSLT way: <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:template match="page"> <div id="skill"> <table border="0" cellpadding="1" cellspacing="1"> <tr> <th>Level</th> </tr> <xsl:for-each select="/page/Skill"> <tr> <td> <xsl:choose> <xsl:when test="@level = 0"> Level 1 </xsl:when> <xsl:when test="@level = 1"> Level 2 </xsl:when> <xsl:when test="@level = 2"> Level 3 </xsl:when> <xsl:otherwise> unknown </xsl:otherwisexsl:otherwise> </xsl:choose> </td> </tr> </xsl:for-each> </table> </div> </xsl:template> </xsl:stylesheet> EDIT: Also, I have some inline javascript functions for form submit. <input type="submit" onclick="javascript:document.forms[0].submit();return false;"/>

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  • How to persist non-trivial fields in Play Framework

    - by AlexR
    I am trying to persist complex objects using Ebeans in Play Framework (2.03). In particular, I've created a class that contains a field of type weka.classifier.Classifier (Weka is a popular machine learning library - see http://weka.sourceforge.net/doc/weka/classifiers/Classifier.html). Classifier implements Serializeable so I hoped that I can get away with something like @Entity @Table(name = "classifiers") public class ClassifierData extends Model { @Id public Long id; public Classifier classifier; } However, the Evolutions script suggests the following database structure: create table classifiers ( id bigint auto_increment not null, constraint pk_classifiers primary key (id)) ) In other words, it ignores the field of type Classifier. (The database is MySQL if it makes any difference) What should I do to store complex serializeable objects using Ebean/Evolutions/PlayFramework?

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  • How to use Dbmapper to generate JPA entity classes from DB script?

    - by Sourabh
    I am tring to use http://code.google.com/p/dbmapper/ and I am not sure how to run it frmo the command prompt. The sample usesege is like below Usage: com.moonspider.dbmap.GenerateConfig -type (-t) [String] The type to generate, either 'jpa' or 'gorm' (experimental) (jpa) -destinationDirectory (-d) [String] Destination directory -url [String] The url of the database -pkg (-package) [String] The target package () -user (-u) [String] Database user (sa) -password (-p) [String] Database password () -globalExtends (-extends) [String] Class for all Java classes to extend -globalImplements (-implements) [String] Class for all Java classes to implement -driver [String] Database drive class -extension (-ext) [String] File extension for the generated code (java) -hibernate [String] Generate hibernate.cfg.xml to this directory -jaxb [flag] Enable xml binding generation -schema [String] Specify the non-default schema to use How to run com.moonspider.dbmap.GenerateConfig from command line ?

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  • How to determine which side of a 3D plane is showing?

    - by Josh Santangelo
    This is a 3d n00b question. I'm working on a WPF control which implements the basics of Silverlight's PerspectiveTransform feature, allowing a 2D plane to be rotated on any of the three axes. It works pretty well. However I'm a little stuck on the math required to determine whether or not the back of the plane is showing. My naive code for figuring that out now is: bool isBackShowing = Math.Abs(RotationX) > 90 && Math.Abs(RotationY) < 90; if (!isBackShowing) { isBackShowing = Math.Abs(RotationX) < 90 && Math.Abs(RotationY) > 90; } However, this fails when the rotation is between +-270 and +-360 on either axis. The underlying transform is using a Quaternion object to do the actual rotation, and that has nice Axis and Angle properties, so I'm guessing I could just use that if I knew how.

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  • What is "sentry object" in C++?

    - by Romain Hippeau
    I answered this question, and Potatoswatter answered too as The modern C++ equivalent would be a sentry object: construct it at the beginning of a function, with its constructor implementing call(), and upon return (or abnormal exit), its destructor implements I am not familiar with using sentry objects in C++. I thought they were limited to input and output streams. Could somebody explain to me about C++ sentry objects as well as how to use them as an around interceptor for one or more methods in a class ? i.e. How to do this ? Sentry objects are very similar indeed. On the one hand they require explicit instantiation (and being passed this) but on the other hand you can add to them so that they check not only the invariants of the class but some pre/post conditions for the function at hand.

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  • Mimic an HTTPRequest and HTTPResponse object in Java

    - by Ankur
    How do I mimic an HTTPServletRequest and HTTPServletResponse object. The reason is I want to test the behaviour of some servlets. I know JUnit probably provides this functionality but I don't know how to use it (I will learn soon) and need to do this reasonably quickly. HTTPServletRequest and HTTPServletResponse are both interfaces so they can't be instantiated. There is a HttpServletRequestWrapper which implements HttpServletRequest but it doesn't seem to have any setParameter() type methods and HttpServletResponse doesn't seem to have any implementing classes at all. How can I test my code by passing a suitable HttpServletRequest object and then checking that the received HttpServletResponse object matches what I expect?

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  • Jpa subclass mapping

    - by Roy Chan
    I am making a POS like system. I wonder how to map subclass using JPA (this is for my DAO). Product class has product details and OrderProduct class has information about the Product and details about the order. @Entity @Table(name="products") public class Product implements Serializable{ @Id @Column(name="id") @GeneratedValue(strategy = GenerationType.AUTO public int getId(){ return id;} /** Other get/set methods */ } @Entity @Table(name="order_products") public class OrderProduct extends Product{ @Id @Column(name="id") @GeneratedValue(strategy = GenerationType.AUTO) public int getId(){ return id;} /** Other get/set methods */ } I got complain about duplicate @Id. But OrderProduct class really need another id than the product one. How should I map this? DB is something like this Table products id int name varchar(32) Table order_product id int quantity int productid int fk referencing product table Would @IdClass or @AttributeOverride help?

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  • Update JProgressBar from new Thread

    - by Dacto
    How can I update the JProgressBar.setValue(int) from another thread? My secondary goal is do it in the least amount of classes possible. Here is the code I have right now: **Part of the main class....** pp.addActionListener( new ActionListener(){ public void actionPerformed(ActionEvent event) { new Thread(new Task(sd.getValue())).start(); } }); public class Task implements Runnable{ int val; public Task(int value){ this.val = value; } @Override public void run() { for (int i=0; i<=value; i++){ //Progressively increment variable i pbar.setValue(i); //Set value pbar.repaint(); //Refresh graphics try{Thread.sleep(50);} //Sleep 50 milliseconds catch (InterruptedException err){} } } } pp is a JButton and starts the new thread when the JButton is clicked. pbar is the JProgressBar object from the Main class. How can I update its value?(progress) The code above in run() cannot see the pbar.

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  • Cast MyEntity To LinqEntity throw a base controller class

    - by Mohammad Kani
    hi there i design a multilayer we appliction andusing LINQ a my data provider i need to user my own Entites instead o LINQ etities. so i created Entities Project and create my entities in it. when i get data from contex and cast them to my entities , everything is ok. but when i want to cast on of my entities to linq entity , an exception thrown. in my linq entity i add CTYPE operator from and to my entities Exp : Public Class BaseController(Of LinqEntity As {BaseEntity, New}, MyEntity As ModuleEntities.BaseEntityInfo) Implements Interfaces.Base(Of ServiceEntity) 'This methd work fine and cast LinqEntity to MyEntity Public Function GetAll() As List(Of MyEntity ) Dim q = (From x In Context.GetTable(Of LinqEntity)() _ Select x).Cast(Of MyEntityBase) End Function Public Sub Update(ByVal entity As MyEntity) 'here is problem 'cast , direct cast , or anything not work Dim x as LinqEntity = entity Me.Context.GetTable(Of LinqEntity).InsertOnSubmit(entity) Me.Context.SubmiChanges() End Sub

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  • java: relationship of the Runnable and Thread interfaces

    - by Karl Patrick
    I realize that the method run() must be declared because its declared in the Runnable interface. But my question comes when this class runs how is the Thread object allowed if there is no import call to a particular package? how does runnable know anything about Thread or its methods? does the Runnable interface extend the Thread class? Obviously I don't understand interfaces very well. thanks in advance. class PrimeFinder implements Runnable{ public long target; public long prime; public boolean finished = false; public Thread runner; PrimeFinder(long inTarget){ target = inTarget; if(runner == null){ runner = new Thread(this); runner.start() } } public void run(){ } }

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  • Possible Performance Considerations using Linq to SQL Repositories

    - by Robert Harvey
    I have an ASP.NET MVC application that uses Linq to SQL repositories for all interactions with the database. To deal with data security, I do trimming to filter data to only those items to which the user has access. This occurs in several places: Data in list views Links in a menu bar A treeview on the left hand side containing links to content Role-based security A special security attribute, inheriting from AuthorizeAttribute, that implements content-based authorization on every controller method. Each of these places instantiates a repository, which opens a Linq to Sql DataContext and accesses the database. So, by my count, each request for a page access opens at least six separate Linq to SQL DataContexts. Should I be concerned about this from a performance perspective, and if so, what can be done to mitigate it?

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