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• How to get Type[] of all classes a class extends

  - by Jeff Dahmer

  You can do Type[] interfaces = typeof(MyClass).GetInterfaces(); to get a list of everything a class implements implements. I am wondering if there is anyway to crawl the "extends" tree to see all the base types a class inherits, i.e. abstract classes etc.?

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• Why can a List(Of SomeObject) not be converted to an IEnumerable(Of ISomeInterface) while SomeObject

  - by ropstah

  Please see the last comment in GetListChildren() function. "Why can a List(Of Page) not be converted to an IEnumerable(Of IListHasChildren) ?" Interface IListHasChildren Function GetListChildren() as IEnumerable(Of IListHasChildren) End Interface Public Class Page : Implements IListHasChildren Public Function GetChildren() As List(Of Page) //'return List(Of Page) with children End Function Public Function GetListChildren() : Implements IListHasChildren.GetListChildren Return Me.GetChildren() //'This cannot be converted to IEnumerable(Of IListHasChildren) ?? End Function End Class

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• What's new in EJB 3.2 ? - Java EE 7 chugging along!

  - by arungupta

  EJB 3.1 added a whole ton of features for simplicity and ease-of-use such as @Singleton, @Asynchronous, @Schedule, Portable JNDI name, EJBContainer.createEJBContainer, EJB 3.1 Lite, and many others. As part of Java EE 7, EJB 3.2 (JSR 345) is making progress and this blog will provide highlights from the work done so far. This release has been particularly kept small but include several minor improvements and tweaks for usability. More features in EJB.Lite Asynchronous session bean Non-persistent EJB Timer service This also means these features can be used in embeddable EJB container and there by improving testability of your application. Pruning - The following features were made Proposed Optional in Java EE 6 and are now made optional. EJB 2.1 and earlier Entity Bean Component Contract for CMP and BMP Client View of an EJB 2.1 and earlier Entity Bean EJB QL: Query Language for CMP Query Methods JAX-RPC-based Web Service Endpoints and Client View The optional features are moved to a separate document and as a result EJB specification is now split into Core and Optional documents. This allows the specification to be more readable and better organized. Updates and Improvements Transactional lifecycle callbacks in Stateful Session Beans, only for CMT. In EJB 3.1, the transaction context for lifecyle callback methods (@PostConstruct, @PreDestroy, @PostActivate, @PrePassivate) are defined as shown. @PostConstruct @PreDestroy @PrePassivate @PostActivate Stateless Unspecified Unspecified N/A N/A Stateful Unspecified Unspecified Unspecified Unspecified Singleton Bean's transaction management type Bean's transaction management type N/A N/A In EJB 3.2, stateful session bean lifecycle callback methods can opt-in to be transactional. These methods are then executed in a transaction context as shown. @PostConstruct @PreDestroy @PrePassivate @PostActivate Stateless Unspecified Unspecified N/A N/A Stateful Bean's transaction management type Bean's transaction management type Bean's transaction management type Bean's transaction management type Singleton Bean's transaction management type Bean's transaction management type N/A N/A For example, the following stateful session bean require a new transaction to be started for @PostConstruct and @PreDestroy lifecycle callback methods. @Statefulpublic class HelloBean {   @PersistenceContext(type=PersistenceContextType.EXTENDED)   private EntityManager em;    @TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)   @PostConstruct   public void init() {        myEntity = em.find(...);   }   @TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)    @PostConstruct    public void destroy() {        em.flush();    }} Notice, by default the lifecycle callback methods are not transactional for backwards compatibility. They need to be explicitly opt-in to be made transactional. Opt-out of passivation for stateful session bean - If your stateful session bean needs to stick around or it has non-serializable field then the bean can be opt-out of passivation as shown. @Stateful(passivationCapable=false)public class HelloBean {    private NonSerializableType ref = ... . . .} Simplified the rules to define all local/remote views of the bean. For example, if the bean is defined as: @Statelesspublic class Bean implements Foo, Bar {    . . .} where Foo and Bar have no annotations of their own, then Foo and Bar are exposed as local views of the bean. The bean may be explicitly marked @Local as @Local@Statelesspublic class Bean implements Foo, Bar {    . . .} then this is the same behavior as explained above, i.e. Foo and Bar are local views. If the bean is marked @Remote as: @Remote@Statelesspublic class Bean implements Foo, Bar {    . . .} then Foo and Bar are remote views. If an interface is marked @Local or @Remote then each interface need to be explicitly marked explicitly to be exposed as a view. For example: @Remotepublic interface Foo { . . . }@Statelesspublic class Bean implements Foo, Bar {    . . .} only exposes one remote interface Foo. Section 4.9.7 from the specification provide more details about this feature. TimerService.getAllTimers is a newly added convenience API that returns all timers in the same bean. This is only for displaying the list of timers as the timer can only be canceled by its owner. Removed restriction to obtain the current class loader, and allow to use java.io package. This is handy if you want to do file access within your beans. JMS 2.0 alignment - A standard list of activation-config properties is now defined destinationLookup connectionFactoryLookup clientId subscriptionName shareSubscriptions Tons of other clarifications through out the spec. Appendix A provide a comprehensive list of changes since EJB 3.1. ThreadContext in Singleton is guaranteed to be thread-safe. Embeddable container implement Autocloseable. A complete replay of Enterprise JavaBeans Today and Tomorrow from JavaOne 2012 can be seen here (click on CON4654_mp4_4654_001 in Media). The specification is still evolving so the actual property or method names or their actual behavior may be different from the currently proposed ones. Are there any improvements that you'd like to see in EJB 3.2 ? The EJB 3.2 Expert Group would love to hear your feedback. An Early Draft of the specification is available. The latest version of the specification can always be downloaded from here. Java EE 7 Specification Status EJB Specification Project JIRA of EJB Specification JSR Expert Group Discussion Archive These features will start showing up in GlassFish 4 Promoted Builds soon.

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• How to Open Any Folder as a Project in the NetBeans Platform

  - by Geertjan

  Typically, as described in the NetBeans Project Type Tutorial, you'll define a project type based on the presence of a file (e.g., "project.xml" or "customer.txt" or something like that) in a folder. I.e., if the file is there, then its parent, i.e., the folder that contains the file, is a project and should be opened in your application. However, in some scenarios (as with the HTML5 project type introduced in NetBeans IDE 7.3), the user should be able to open absolutely any folder at all into the application. How to create a project type that is that liberal? Here you go, the only condition that needs to be true is that the selected item in the "Open Project" dialog is a folder, as defined in the "isProject" method below. Nothing else. That's it. If you select a folder, it will be opened in your application, displaying absolutely everything as-is (since below there's no ProjectLogicalView defined): import java.beans.PropertyChangeListener; import java.io.IOException; import javax.swing.Icon; import org.netbeans.api.project.Project; import org.netbeans.api.project.ProjectInformation; import org.netbeans.spi.project.ProjectFactory; import org.netbeans.spi.project.ProjectState; import org.openide.filesystems.FileObject; import org.openide.loaders.DataFolder; import org.openide.loaders.DataObjectNotFoundException; import org.openide.nodes.FilterNode; import org.openide.util.Exceptions; import org.openide.util.ImageUtilities; import org.openide.util.Lookup; import org.openide.util.lookup.Lookups; import org.openide.util.lookup.ServiceProvider; @ServiceProvider(service = ProjectFactory.class) public class FolderProjectFactory implements ProjectFactory { @Override public boolean isProject(FileObject projectDirectory) { return DataFolder.findFolder(projectDirectory) != null; } @Override public Project loadProject(FileObject dir, ProjectState state) throws IOException { return isProject(dir) ? new FolderProject(dir) : null; } @Override public void saveProject(Project prjct) throws IOException, ClassCastException { // leave unimplemented for the moment } private class FolderProject implements Project { private final FileObject projectDir; private Lookup lkp; private FolderProject(FileObject dir) { this.projectDir = dir; } @Override public FileObject getProjectDirectory() { return projectDir; } @Override public Lookup getLookup() { if (lkp == null) { lkp = Lookups.fixed(new Object[]{ new Info(), }); } return lkp; } private final class Info implements ProjectInformation { @Override public Icon getIcon() { Icon icon = null; try { icon = ImageUtilities.image2Icon( new FilterNode(DataFolder.find( getProjectDirectory()).getNodeDelegate()).getIcon(1)); } catch (DataObjectNotFoundException ex) { Exceptions.printStackTrace(ex); } return icon; } @Override public String getName() { return getProjectDirectory().getName(); } @Override public String getDisplayName() { return getName(); } @Override public void addPropertyChangeListener(PropertyChangeListener pcl) { //do nothing, won't change } @Override public void removePropertyChangeListener(PropertyChangeListener pcl) { //do nothing, won't change } @Override public Project getProject() { return FolderProject.this; } } } } Even the ProjectInformation implementation really isn't needed at all, since it provides nothing more than the icon in the "Open Project" dialog, the rest (i.e., the display name in the "Open Project" dialog) is provided by default regardless of whether you have a ProjectInformation implementation or not.

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• Wpf binding to a function

  - by carlopenid

  I've a created a simple scrollviewer (pnlDayScroller) and want to have a separate horizontal scrollbar (associated scroller) to do the horizontal scrolling. All works with the below code accept I need to bind the visibility of the associated scroller. I can't simply bind this to the visibility property of the horizontal template part of the scroll viewer as I've set this to be always hidden. The only way I can think to do this is to bind the visibility of the associated scroller to a function such that If associatedScroller.scrollableWidth > 0 then associatedScroller.visibility = visibility.visible else associatedScroller.visibility = visibility.collapsed end if Is this possible to do and if so how do I do it? Private Sub pnlDayScroller_Loaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles pnlDayScroller.Loaded Dim binViewport, binMax, binMin, binSChange, binLChange As Binding Dim horizontalScrollBar As Primitives.ScrollBar = CType(pnlDayScroller.Template.FindName("PART_HorizontalScrollBar", pnlDayScroller), Primitives.ScrollBar) binViewport = New Binding("ViewportSize") binViewport.Mode = BindingMode.OneWay binViewport.Source = horizontalScrollBar associatedScroller.SetBinding(Primitives.ScrollBar.ViewportSizeProperty, binViewport) binMax = New Binding("Maximum") binMax.Mode = BindingMode.OneWay binMax.Source = horizontalScrollBar associatedScroller.SetBinding(Primitives.ScrollBar.MaximumProperty, binMax) binMin = New Binding("Minimum") binMin.Mode = BindingMode.OneWay binMin.Source = horizontalScrollBar associatedScroller.SetBinding(Primitives.ScrollBar.MinimumProperty, binMin) binSChange = New Binding("SmallChange") binSChange.Mode = BindingMode.OneWay binSChange.Source = horizontalScrollBar associatedScroller.SetBinding(Primitives.ScrollBar.SmallChangeProperty, binSChange) binLChange = New Binding("LargeChange") binLChange.Mode = BindingMode.OneWay binLChange.Source = horizontalScrollBar associatedScroller.SetBinding(Primitives.ScrollBar.LargeChangeProperty, binLChange) End Sub Private Sub associatedScroller_Scroll(ByVal sender As System.Object, ByVal e As System.Windows.RoutedPropertyChangedEventArgs(Of Double)) Handles associatedScroller.ValueChanged pnlDayScroller.ScrollToHorizontalOffset(e.NewValue) end sub FOLLOW UP (thanks to JustABill) : I've add this code into the pnlDayScroller sub above (I've discovered scrollableWidth is a property of scrollviewer not scrollbar, but the maximum property gives a result I can use instead) binVisibility = New Binding("Maximum") binVisibility.Mode = BindingMode.OneWay binVisibility.Source = horizontalScrollBar binVisibility.Converter = New ScrollableConverter associatedScroller.SetBinding(Primitives.ScrollBar.VisibilityProperty, binVisibility) and I've created this class Public Class ScrollableConverter Implements IValueConverter Public Function Convert(ByVal value As Object, ByVal targetType As Type, ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object Implements IValueConverter.Convert Dim dblMaximum As Double If targetType IsNot GetType(Visibility) Then Throw New InvalidOperationException("The target must be a visibility") Else dblMaximum = CType(value, Double) Debug.WriteLine("Value of double is " & dblMaximum) If dblMaximum > 0 Then Return Visibility.Visible Else Return Visibility.Collapsed End If End If End Function Public Function ConvertBack(ByVal value As Object, ByVal targetType As Type, ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object Implements IValueConverter.ConvertBack Throw New NotSupportedException() End Function End Class And the problem is resolved.

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• How to handle EntityExistsException properly?

  - by Ivan Yatskevich

  I have two entities: Question and FavoritesCounter. FavoritesCounter should be created when the question is added to favorites for the first time. Consider a use case when two users tries to add a question to favorites simultaneously - this will cause EntityExistsException when entityManager.persist(counter) is called for the second user. But the code below doesn't work, because when EntityExistsException is thrown, container marks transaction as rollback only and attempt to return getFavoritesCounter(question) fails with javax.resource.ResourceException: Transaction is not active @Stateless public class FavoritesServiceBean implements FavoritesService { ... public void addToFavorites(Question question) { FavoritesCounter counter = getCounter(question); if (counter == null) { counter = createCounter(question); } //increase counter } private FavoritesCounter createCounter(Question question) { try { FavoritesCounter counter = new FavoritesCounter(); counter.setQuestion(question); entityManager.persist(counter); entityManager.flush(); return counter; } catch (EntityExistsException e) { return getFavoritesCounter(question); } } private FavoritesCounter getFavoritesCounter(Question question) { Query counterQuery = entityManager.createQery("SELECT counter FROM FavoritesCounter counter WHERE counter.question = :question"); counterQuery.setParameter("question", question); List<FavoritesCounter> result = counterQuery.getResultList(); if (result.isEmpty()) return null; return result.get(0); } } Question @Entity public class Question implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; //getter and setter for id } FavoritesCounter @Entity public class FavoritesCounter implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; @OneToOne @Column(unique = true) private Question question; //getter and setter } What is the best way to handle such a situation - return already created entity after EntityExistsException?

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• JPA association table is not deletable

  - by Marcel

  Hi I have a problem with JPA (EclipseLink). I am not able to delete a association table. This is the situation: Product 1:n to ProductResource Resource 1:n to ProductResource I first set the product and resource attributes of ProductResource. If I then try to delete the ProductResource object nothing happens (no sql is generated - no exception). If I comment out both OneToMany annotations in ProductResource I can delete the object. I can also delete the object when product and resource attributes are not set. If I comment out only the annotation above the ressource attribut the ProductResource object gets deleted upon the deletion of the product object (cascade=CascadeType.ALL). I hope someone could give me a hint. Thank you. Product Resource: public class ProductResource implements Serializable { @ManyToOne(fetch=FetchType.EAGER, cascade=CascadeType.MERGE) private Product product; @ManyToOne(fetch=FetchType.EAGER, cascade=CascadeType.MERGE) private Resource resource; Product: public class Product implements Serializable { @OneToMany(mappedBy="product", fetch=FetchType.EAGER, cascade=CascadeType.ALL) private List<ProductResource> productResources = new ArrayList<ProductResource>(); Resource: public class Resource implements Serializable { @OneToMany(mappedBy="resource", fetch=FetchType.EAGER, cascade=CascadeType.ALL) private List<ProductResource> productResources = new ArrayList<ProductResource>(); Greetings Marcel

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• Compile error on inheritance of generic inner class extending with bounds

  - by Arne Burmeister

  I have a problem when compiling a generic class with an inner class. The class extends a generic class, the inner class also. Here the interface implemented: public interface IndexIterator<Element> extends Iterator<Element> { ... } The generic super class: public abstract class CompoundCollection<Element, Part extends Collection<Element>> implements Collection<Element> { ... protected class CompoundIterator<Iter extends Iterator<Element>> extends ImmutableIterator<Element> { ... } } The generic subclass with the compiler error: public class CompoundList<Element> extends CompoundCollection<Element, List<Element>> implements List<Element> { ... private class CompoundIndexIterator extends CompoundIterator<IndexIterator<Element>> implements IndexIterator<Element> { ... } } The error is: type parameter diergo.collect.IndexIterator<Element> is not within its bound extends CompoundIterator<IndexIterator<Element>> ^ What is wrong? The code compiles with eclipse, but bot with java 5 compiler (I use ant with java 5 on a mac and eclipse 3.5). No, I cannot convert it to a static inner class.

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• ADT-like polymorphism in Java (without altering class)

  - by ffriend

  In Haskell I can define following data type: data Tree = Empty | Leaf Int | Node Tree Tree and then write polymorphic function like this: depth :: Tree -> Int depth Empty = 0 depth (Leaf n) = 1 depth (Node l r) = 1 + max (depth l) (depth r) In Java I can emulate algebraic data types with interfaces: interface Tree {} class Empty implements Tree {} class Leaf implements Tree { int n; } class Node implements Tree { Tree l; Tree r; } But if I try to use Haskell-like polymorphism, I get an error: int depth(Empty node) { return 0; } int depth(Leaf node) { return 1; } int depth(Node node) { return 1 + Math.max(depth(node.l), depth(node.r)); // ERROR: Cannot resolve method 'depth(Tree)' } Correct way to overcome this is to put method depth() to each class. But what if I don't want to put it there? For example, method depth() may be not directly related to Tree and adding it to class would break business logic. Or, even worse, Tree may be written in 3rd party library that I don't have access to. In this case, what is the simplest way to implement ADT-like polymorpism? Just in case, for the moment I'm using following syntax, which is obviously ill-favored: int depth(Tree tree) { if (tree instanceof Empty) depth((Empty)tree) if (tree instanceof Leaf) depth((Leaf)tree); if (tree instanceof Node) depth((Node)tree); else throw new RuntimeException("Don't know how to find depth of " + tree.getClass()); }

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• @Autowire strange problem

  - by Javi

  Hello, I have a strange behaviour when autowiring I have a similar code like this one, and it works @Controller public class Class1 { @Autowired private Class2 object2; ... } @Service @Transactional public class Class2{ ... } The problem is that I need that the Class2 implements an interface so I've only changed the Class2 so it's now like: @Controller public class Class1 { @Autowired private Class2 object2; ... } @Service @Transactional public class Class2 implements IServiceReference<Class3, Long>{ ... } public interface IServiceReference<T, PK extends Serializable> { public T reference(PK id); } with this code I get a org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type for Class2. It seems that @ Transitional annotation is not compatible with the interface because if I remove the @Transitional annotation or the "implements IServiceReference" the problem disapears and the bean is injected (though I need to have both in this class). It also happens if I put the annotation @Transitional in the methods instead of in the Class. I use Spring 3.0.2 if this helps. Is not compatible the interface with the transactional method? May it be a Spring bug? Thanks

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• Why would the VB.NET compiler think an interface isn't implemented when it is?

  - by Dan Tao

  I have this happen sometimes, particularly with the INotifyPropertyChanged interface in my experience but I have no idea if the problem is limited to that single interface (which would seem bizarre) or not. Let's say I have some code set up like this. There's an interface with a single event. A class implements that interface. It includes the event. Public Interface INotifyPropertyChanged Event PropertyChanged As PropertyChangedEventHandler End Interface Public Class Person Implements INotifyPropertyChanged Public Event PropertyChanged _ (ByVal sender As Object, ByVal e As PropertyChangedEventArgs) _ Implements INotifyPropertyChanged.PropertyChanged ' more code below ' End Class Every now and then, when I build my project, the compiler will suddenly start acting like the above code is broken. It will report that the Person class does not implement INotifyPropertyChanged because it doesn't have a PropertyChanged event; or it will say the PropertyChanged event can't implement INotifyPropertyChanged.PropertyChanged because their signatures don't match. This is weird enough as it is, but here's the weirdest part: if I just cut out the line starting with Event PropertyChanged and then paste it back in, the error goes away. The project builds. Does anybody have any clue what could be going on here?

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• Iterator performance contract (and use on non-collections)

  - by polygenelubricants

  If all that you're doing is a simple one-pass iteration (i.e. only hasNext() and next(), no remove()), are you guaranteed linear time performance and/or amortized constant cost per operation? Is this specified in the Iterator contract anywhere? Are there data structures/Java Collection which cannot be iterated in linear time? java.util.Scanner implements Iterator<String>. A Scanner is hardly a data structure (e.g. remove() makes absolutely no sense). Is this considered a design blunder? Is something like PrimeGenerator implements Iterator<Integer> considered bad design, or is this exactly what Iterator is for? (hasNext() always returns true, next() computes the next number on demand, remove() makes no sense). Similarly, would it have made sense for java.util.Random implements Iterator<Double>? Should a type really implement Iterator if it's effectively only using one-third of its API? (i.e. no remove(), always hasNext())

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• Mapping Hashmap of Coordinates in Hibernate with Annotation

  - by paddydub

  I've just started using hibernate and I'm trying to map walking distance between two coordinates into a hashmap, There can be many connections from one "FromCoordinate" to another "ToCoordinate". I'm not sure if i've implemented this correctly, What annotations do i need to map this MashMap? Thanks HashMap coordWalkingConnections = new HashMap(); @Entity @Table(name = "COORDCONNECTIONS") public class CoordinateConnection implements Serializable{ private static final long serialVersionUID = -1624745319005591573L; /** auto increasing id number */ @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "ID") @id private int id; @Embedded public FromCoordinate fromCoord; @Embedded public ToCoordinate toCoord; HashMap<FromCoordinate, ArrayList<ToCoordinate >> coordWalkingConnections = new HashMap<FromCoordinate, ArrayList<ToCoordinate >>(); } public class FromCoordinate implements ICoordinate { @Column(name = "FROM_LAT") private double latitude; @Column(name = "FROM_LNG") private double longitude; } public class ToCoordinate implements ICoordinate { @Column(name = "TO_LAT") private double latitude; @Column(name = "TO_LNG") private double longitude; @Column(name = "DISTANCE") private double distance; } DATABASE STRUCTURE id FROM_LAT FROM_LNG TO_LAT TO_LNG Dist 1 43.352669 -6.264341 43.350012 -6.260653 0.38 2 43.352669 -6.264341 43.352669 -6.264341 0.00 3 46.352669 -6.264341 43.353373 -6.262013 0.17 4 47.352465 -6.265865 43.351290 -6.261200 0.25 5 45.452578 -6.265768 43.352788 -6.264396 0.01 6 45.452578 -6.265768 45.782788 -6.234523 0.01 ..... ... . Example HashMap for HashMap<Coordinate, ArrayList<Coordinate>> <KEY{43.352669 -6.264341}, Arraylist VALUES{(43.350012,-6.260653,0.383657), (43.352669, -6.264341, 0.000095), (43.353373, -6.262013, 0.173201)}> <KEY{47.352465 -6.265865}, Arraylist VALUES{(43.351290,-6.261200,0.258781)}> <KEY{45.452578 -6.265768}, Arraylist VALUES{(43.352788,-6.264396,0.013726),(45.782788,-6.234523,0.017726)}>

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• Hibernate Mapping Annotation Question?

  - by paddydub

  I've just started using hibernate and I'm trying to map walking distance between two coordinates into a hashmap, There can be many connections from one "FromCoordinate" to another "ToCoordinate". I'm not sure if i've implemented this correctly, What annotations do i need to map this MashMap? Thanks @Entity @Table(name = "COORDCONNECTIONS") public class CoordinateConnection implements Serializable{ private static final long serialVersionUID = -1624745319005591573L; /** auto increasing id number */ @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "ID") @id private int id; @Embedded public FromCoordinate fromCoord; @Embedded public ToCoordinate toCoord; HashMap<Coordinate, ArrayList<Coordinate>> coordWalkingConnections = new HashMap<Coordinate, ArrayList<Coordinate>>(); } public class FromCoordinate implements ICoordinate { @Column(name = "FROM_LAT") private double latitude; @Column(name = "FROM_LNG") private double longitude; } public class ToCoordinate implements ICoordinate { @Column(name = "TO_LAT") private double latitude; @Column(name = "TO_LNG") private double longitude; @Column(name = "DISTANCE") private double distance; } DATABASE STRUCTURE id FROM_LAT FROM_LNG TO_LAT TO_LNG Dist 1 43.352669 -6.264341 43.350012 -6.260653 0.38 2 43.352669 -6.264341 43.352669 -6.264341 0.00 3 46.352669 -6.264341 43.353373 -6.262013 0.17 4 47.352465 -6.265865 43.351290 -6.261200 0.25 5 45.452578 -6.265768 43.352788 -6.264396 0.01 6 45.452578 -6.265768 45.782788 -6.234523 0.01 ..... ... . Example HashMap for HashMap<Coordinate, ArrayList<Coordinate>> <KEY{43.352669 -6.264341}, Arraylist VALUES{(43.350012,-6.260653,0.383657), (43.352669, -6.264341, 0.000095), (43.353373, -6.262013, 0.173201)}> <KEY{47.352465 -6.265865}, Arraylist VALUES{(43.351290,-6.261200,0.258781)}> <KEY{45.452578 -6.265768}, Arraylist VALUES{(43.352788,-6.264396,0.013726),(45.782788,-6.234523,0.017726)}>

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• Create dynamic factory method in PHP (< 5.3)

  - by fireeyedboy

  How would one typically create a dynamic factory method in PHP? By dynamic factory method, I mean a factory method that will autodiscover what objects there are to create, based on some aspect of the given argument. Preferably without registering them first with the factory either. I'm OK with having the possible objects be placed in one common place (a directory) though. I want to avoid your typical switch statement in the factory method, such as this: public static function factory( $someObject ) { $className = get_class( $someObject ); switch( $className ) { case 'Foo': return new FooRelatedObject(); break; case 'Bar': return new BarRelatedObject(); break; // etc... } } My specific case deals with the factory creating a voting repository based on the item to vote for. The items all implement a Voteable interface. Something like this: Default_User implements Voteable ... Default_Comment implements Voteable ... Default_Event implements Voteable ... Default_VoteRepositoryFactory { public static function factory( Voteable $item ) { // autodiscover what type of repository this item needs // for instance, Default_User needs a Default_VoteRepository_User // etc... return new Default_VoteRepository_OfSomeType(); } } I want to be able to drop in new Voteable items and Vote repositories for these items, without touching the implementation of the factory.

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• JME: How to get the complete screen in WHITE without buttons, etc etc

  - by Sepala

  Please have a look at the following code /* * To change this template, choose Tools | Templates * and open the template in the editor. */ import javax.microedition.midlet.*; import javax.microedition.lcdui.*; /** */ public class Midlet extends MIDlet{ private Form f; private Display d; private Command start,stop; private Thread t; public Midlet() { t = new Thread(new TurnLightOn()); } public void startApp() { f = new Form("Back Light On"); d = Display.getDisplay(this); d.setCurrent(f); start = new Command("Turn On",Command.OK,0); stop = new Command("Turn Off",Command.OK,1); f.addCommand(start); f.setCommandListener(new Action()); } public void pauseApp() { } public void destroyApp(boolean unconditional) { this.notifyDestroyed(); } private class Action implements CommandListener { public void commandAction(Command c, Displayable dis) { f.append("Light is Turnning On"); t.start(); } } private class ActionOff implements CommandListener { public void commandAction(Command c, Displayable dis) { } } private class TurnLightOn implements Runnable { public void run() { f.append("Working"); for(int i=0;i<100;i++) { try { d.flashBacklight(200); d.vibrate(200); Thread.sleep(1000); } catch (InterruptedException ex) { ex.printStackTrace(); } } } } } First, Please note I am a 100% newbie to Java Mobile. In here, I am making the light on and vibrate on when user click the button. However, I really wanted to create a SOS application which turn the whole screen into white, and go to black, like that, in the thread. I guess I didn't achieve that by this app because even the lights are on, the buttons are still there. I tried to turn the "Form" color to "white" but it seems like JME has no "Color" class! Please help!

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• JPA - Entity design problem

  - by Yatendra Goel

  I am developing a Java Desktop Application and using JPA for persistence. I have a problem mentioned below: I have two entities: Country City Country has the following attribute: CountryName (PK) City has the following attribute: CityName Now as there can be two cities with same name in two different countries, the primaryKey for City table in the datbase is a composite primary key composed of CityName and CountryName. Now my question is How to implement the primary key of the City as an Entity in Java @Entity public class Country implements Serializable { private String countryName; @Id public String getCountryName() { return this.countryName; } } @Entity public class City implements Serializable { private CityPK cityPK; private Country country; @EmbeddedId public CityPK getCityPK() { return this.cityPK; } } @Embeddable public class CityPK implements Serializable { public String cityName; public String countryName; } Now as we know that the relationship from Country to City is OneToMany and to show this relationship in the above code, I have added a country variable in City class. But then we have duplicate data(countryName) stored in two places in the City class: one in the country object and other in the cityPK object. But on the other hand, both are necessary: countryName in cityPK object is necessary because we implement composite primary keys in this way. countryName in country object is necessary because it is the standard way of showing relashionship between objects. How to get around this problem?

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• Testing for interface implementation in WCF/SOA

  - by rabidpebble

  I have a reporting service that implements a number of reports. Each report requires certain parameters. Groups of logically related parameters are placed in an interface, which the report then implements: [ServiceContract] [ServiceKnownType(typeof(ExampleReport))] public interface IService1 { [OperationContract] void Process(IReport report); } public interface IReport { string PrintedBy { get; set; } } public interface IApplicableDateRangeParameter { DateTime StartDate { get; set; } DateTime EndDate { get; set; } } [DataContract] public abstract class Report : IReport { [DataMember] public string PrintedBy { get; set; } } [DataContract] public class ExampleReport : Report, IApplicableDateRangeParameter { [DataMember] public DateTime StartDate { get; set; } [DataMember] public DateTime EndDate { get; set; } } The problem is that the WCF DataContractSerializer does not expose these interfaces in my client library, thus I can't write the generic report generating front-end that I plan to. Can WCF expose these interfaces, or is this a limitation of the serializer? If the latter case, then what is the canonical approach to this OO pattern? I've looked into NetDataContractSerializer but it doesn't seem to be an officially supported implementation (which means it's not an option in my project). Currently I've resigned myself to including the interfaces in a library that is common between the service and the client application, but this seems like an unnecessary extra dependency to me. Surely there is a more straightforward way to do this? I was under the impression that WCF was supposed to replace .NET remoting; checking if an object implements an interface seems to be one of the most basic features required of a remoting interface?

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• Eclipselink: Create objects from JOIN query

  - by Raven

  Hi, I have a SQL query SELECT * FROM Thing AS a JOIN Thing_Property AS b ON a.id=b.Thing_ID JOIN Property AS c ON b.properties_ID = c.id JOIN Item AS d ON c.item_ID = d.id ORDER BY a.name, d.name and I Eclipselink to create my object model with it. Here is the model: @SuppressWarnings("serial") @Entity public class Thing implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; private String name; @OneToMany(cascade=CascadeType.ALL) @PrivateOwned private List<Property> properties = new ArrayList<Property>(); ... // getter and setter following here } public class Property implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; @OneToOne private Item item; private String value; ... // getter and setter following here } public class Item implements Serializable { @Id @GeneratedValue(strategy = GenerationType.TABLE) private int id; private String name; .... // getter and setter following here } // Code end but I can not figure out, how to make Eclipselink create the model from that query. Can you help?

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• Java: extending Object class

  - by Fabio F.

  Hello, I'm writing (well, completing) an "extension" of Java which will help role programming. I translate my code to Java code with javacc. My compilers add to every declared class some code. Here's an example to be clearer: MyClass extends String implements ObjectWithRoles { //implements... is added /*Added by me */ public setRole(...){...} public ... /*Ends of stuff added*/ ...//myClass stuff } It adds Implements.. and the necessary methods to EVERY SINGLE CLASS you declare. Quite rough, isnt'it? It will be better if I write my methods in one class and all class extends that.. but.. if class already extends another class (just like the example)? I don't want to create a sort of wrapper that manage roles because i don't want that the programmer has to know much more than Java, few new reserved words and their use. My idea was to extends java.lang.Object.. but you can't. (right?) Other ideas? I'm new here, but I follow this site so thank you for reading and all the answers you give! (I apologize for english, I'm italian)

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• OO - inheritance vs. decoration problem

  - by Karel J

  Hi all, I have an OOP-related question. I have an interface, say: class MyInterface { public int getValue(); } In my project, this interface is implemented by 7 implementations: class MyImplementation1 implements MyInterface { ... } ... class MyImplementation7 implements MyInterface { ... } These implementations are used by several different modules. For some modules, the behaviour of the MyInterface must be adjusted slightly. Let's that it must return the value of the implementator + 1 (for the sake of example). I solved this by creating a little decorator: class MyDifferentInterface implements MyInterface { private MyInterface i; public MyDifferentInterface(MyInterface i) { this.i = i; } public int getValue() { return i.getValue() + 1; } } This does the job. Here is my problem: one of the modules doesn't accept an MyInterface parameter, but MyImplementation4 directly. The reason for this is that this module needs specific behaviour of MyImplementation4, which are not covered by the interface MyInterface on itself. But, and here comes the difficulty, this module must also work on the modified version of MyImplementation4. That is, getValue() must return +1; What is the best way to solve this? I fail to come up with a solution which does not include lots of code duplicates. Please note that although the example above is pretty small and simple, the interface and the decorator is quite large and complicated. Thanks a lot all.

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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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• Two entities with @ManyToOne should join the same table

  - by Ivan Yatskevich

  I have the following entities Student @Entity public class Student implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; //getter and setter for id } Teacher @Entity public class Teacher implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; //getter and setter for id } Task @Entity public class Task implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; @ManyToOne(optional = false) @JoinTable(name = "student_task", inverseJoinColumns = { @JoinColumn(name = "student_id") }) private Student author; @ManyToOne(optional = false) @JoinTable(name = "student_task", inverseJoinColumns = { @JoinColumn(name = "teacher_id") }) private Teacher curator; //getters and setters } Consider that author and curator are already stored in DB and both are in the attached state. I'm trying to persist my Task: Task task = new Task(); task.setAuthor(author); task.setCurator(curator); entityManager.persist(task); Hibernate executes the following SQL: insert into student_task (teacher_id, id) values (?, ?) which, of course, leads to null value in column "student_id" violates not-null constraint Can anyone explain this issue and possible ways to resolve it?

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• Two entities with @ManyToOne joins the same table

  - by Ivan Yatskevich

  I have the following entities Student @Entity public class Student implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; //getter and setter for id } Teacher @Entity public class Teacher implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; //getter and setter for id } Task @Entity public class Task implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; @ManyToOne(optional = false) @JoinTable(name = "student_task", inverseJoinColumns = { @JoinColumn(name = "student_id") }) private Student author; @ManyToOne(optional = false) @JoinTable(name = "student_task", inverseJoinColumns = { @JoinColumn(name = "teacher_id") }) private Teacher curator; //getters and setters } Consider that author and curator are already stored in DB and both are in the attached state. I'm trying to persist my Task: Task task = new Task(); task.setAuthor(author); task.setCurator(curator); entityManager.persist(task); Hibernate executes the following SQL: insert into student_task (teacher_id, id) values (?, ?) which, of course, leads to null value in column "student_id" violates not-null constraint Can anyone explain this issue and possible ways to resolve it?

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• Generic Class Vb.net

  - by KoolKabin

  hi guys, I am stuck with a problem about generic classes. I am confused how I call the constructor with parameters. My interface: Public Interface IDBObject Sub [Get](ByRef DataRow As DataRow) Property UIN() As Integer End Interface My Child Class: Public Class User Implements IDBObject Public Sub [Get](ByRef DataRow As System.Data.DataRow) Implements IDBObject.Get End Sub Public Property UIN() As Integer Implements IDBObject.UIN Get End Get Set(ByVal value As Integer) End Set End Property End Class My Next Class: Public Class Users Inherits DBLayer(Of User) #Region " Standard Methods " #End Region End Class My DBObject Class: Public Class DBLayer(Of DBObject As {New, IDBObject}) Public Shared Function GetData() As List(Of DBObject) Dim QueryString As String = "SELECT * ***;" Dim Dataset As DataSet = New DataSet() Dim DataList As List(Of DBObject) = New List(Of DBObject) Try Dataset = Query(QueryString) For Each DataRow As DataRow In Dataset.Tables(0).Rows **DataList.Add(New DBObject(DataRow))** Next Catch ex As Exception DataList = Nothing End Try Return DataList End Function End Class I get error in the starred area of the DBLayer Object. What might be the possible reason? what can I do to fix it? I even want to add New(byval someval as datatype) in IDBObject interface for overloading construction. but it also gives an error? how can i do it? Adding Sub New(ByVal DataRow As DataRow) in IDBObject producess following error 'Sub New' cannot be declared in an interface. Error Produced in DBLayer Object line: DataList.Add(New DBObject(DataRow)) Msg: Arguments cannot be passed to a 'New' used on a type parameter.

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