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  • I/O between AIR client using Native process and executable java .jar

    - by aseem behl
    I am using Adobe AIR 2.0 native process API to launch a java executable jar. I/O is handled by writing to the input stream of the java process and reading from the output stream. The application is event based where several events are fired from the server. We catch these events in java code, handle them and write the output to the outputstream using the synchronized static method below. public class ReaderWriter { static Logger logger = Logger.getLogger(ReaderWriter.class); public synchronized static void writeToAir(String output){ try{ byte[] byteArray = output.getBytes(); DataOutputStream dataOutputStream = new DataOutputStream(System.out); dataOutputStream.write(byteArray); dataOutputStream.flush(); } catch (IOException e) { logger.info("Exception while writing the output. " + e); } } } The issue is that some messages are lost between the transfer and not all messages reach the AIR client. If I run the java application from the console I am receiving all the messages. It would be great if somebody could point out what I am missing. Following are some of the listeners used to send the event data to the AIR client. // class used to process Shutdown events from the Session private class SessionShutdownListener implements SessionListener{ public void onEvent(Event e) { Session.Shutdown sd = (Session.Shutdown) e; Session.ShutdownReason sr = sd.getReason(); String eventOutput = "eo;" + "Session Shutdown event ocurred reason=" + sr.strValue() + "\n"; ReaderWriter.writeToAir(eventOutput); } } // class used to process OperationSucceeded events from the Session private class SessionOperationSucceededListener implements SessionListener{ public void onEvent(Event e) { Session.OperationSucceeded os = (Session.OperationSucceeded) e; String eventOutput = "eo;" + "Session OperationSucceeded event ocurred" + "\n"; ReaderWriter.writeToAir(eventOutput); } }

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  • Eclipse says I don't implement Enumeration, but I do

    - by Harm De Weirdt
    Goodmorning everybody, I'm having a little problem with a project for school. We are told to make an Iterator that implements Enumeration over a Hashmap. So i made this Enumeration: public Enumeration<Object> getEnumeration() { return new Enumeration<Object>() { private int itemsDone = 0; Collection<Long> keysCollection = getContent().keySet(); Long [] keys = keysCollection.toArray(new Long[keysCollection.size()]); @Override public boolean hasMoreElements() { if(itemsDone < getContent().size() +1 ) { return true; }else { return false; } } @Override public Object nextElement() { return getContent().get(keys[itemsDone++]); } }; } This goes in my Backpack class public class Backpack extends Item implements Carrier, Enumeration<Object>{ The hashmap is returned by getContent(). The problem now is that eclipse keeps telling me I havent implemented the methods from Enumeration. If I use the quick fix it just adds the hasMoreElements() and nextElement() dummy methods in my class. Somehow it doesn't see these methods in the inner class.. Can anyone help me please? Any help is appreciated.

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  • IUsable: controlling resources in a better way than IDisposable

    - by Ilya Ryzhenkov
    I wish we have "Usable" pattern in C#, when code block of using construct would be passed to a function as delegate: class Usable : IUsable { public void Use(Action action) // implements IUsable { // acquire resources action(); // release resources } } and in user code: using (new Usable()) { // this code block is converted to delegate and passed to Use method above } Pros: Controlled execution, exceptions The fact of using "Usable" is visible in call stack Cons: Cost of delegate Do you think it is feasible and useful, and if it doesn't have any problems from the language point of view? Are there any pitfalls you can see? EDIT: David Schmitt proposed the following using(new Usable(delegate() { // actions here }) {} It can work in the sample scenario like that, but usually you have resource already allocated and want it to look like this: using (Repository.GlobalResource) { // actions here } Where GlobalResource (yes, I know global resources are bad) implements IUsable. You can rewrite is as short as Repository.GlobalResource.Use(() => { // actions here }); But it looks a little bit weird (and more weird if you implement interface explicitly), and this is so often case in various flavours, that I thought it deserve to be new syntactic sugar in a language.

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  • How to avoid using this in a constructor

    - by Paralife
    I have this situation: interface MessageListener { void onMessageReceipt(Message message); } class MessageReceiver { MessageListener listener; public MessageReceiver(MessageListener listener, other arguments...) { this.listener = listener; } loop() { Message message = nextMessage(); listener.onMessageReceipt(message); } } and I want to avoid the following pattern: (Using the this in the Client constructor) class Client implements MessageListener { MessageReceiver receiver; MessageSender sender; public Client(...) { receiver = new MessageReceiver(this, other arguments...); sender = new Sender(...); } . . . @Override public void onMessageReceipt(Message message) { if(Message.isGood()) sender.send("Congrtulations"); else sender.send("Boooooooo"); } } The reason why i need the above functionality is because i want to call the sender inside the onMessageReceipt() function, for example to send a reply. But I dont want to pass the sender into a listener, so the only way I can think of is containing the sender in a class that implements the listener, hence the above resulting Client implementation. Is there a way to achive this without the use of 'this' in the constructor? It feels bizare and i dont like it, since i am passing myself to an object(MessageReceiver) before I am fully constructed. On the other hand, the MessageReceiver is not passed from outside, it is constructed inside, but does this 'purifies' the bizarre pattern? I am seeking for an alternative or an assurance of some kind that this is safe, or situations on which it might backfire on me.

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  • Strategies for serializing an object for auditing/logging purpose in .NET?

    - by Jiho Han
    Let's say I have an application that processes messages. Messages are just objects in this case that implements IMessage interface which is just a marker. In this app, if a message fails to process, then I want to log it, first of all for auditing and troubleshooting purposes. Secondly I might want to use it for re-processing. Ideally, I want the message to be serialized into a format that is human-readable. The first candidate is XML although there are others like JSON. If I were to serialize the messages as XML, I want to know whether the message object is XML-serializable. One way is to reflect on the type and to see if it has a parameter-less constructor and the other is to require IXmlSerializable interface. I'm not too happy with either of these approaches. There is a third option which is to try to serialize it and catch exceptions. This doesn't really help - I want to, in some way, stipulate that IMessage (or a derived type) should be xml-serializable. The reflection route has obvious disadvantages such as security, performance, etc. IXmlSerializable route locks down my messages to one format, when in the future, I might want to change the serialization format to be JSON. The other thing is even the simplest objects now must implement ReadXml and WriteXml methods. Is there a route that involves the least amount of work that lets me serialize an arbitrary object (as long as it implements the marker interface) into XML but not lock future messages into XML?

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  • ClassCastException while using service

    - by Sebi
    I defined a local Service: public class ComService extends Service implements IComService { private IBinder binder = new ComServiceBinder(); public class ComServiceBinder extends Binder implements IComService.IServiceBinder { public IComService getService() { return ComService.this; } } public void test(String msg) { System.out.println(msg); } @Override public IBinder onBind(Intent intent) { return binder; } } The corresponding interface: public interface IComService { public void test(String msg); public interface IServiceBinder { IComService getService(); } } Then i try to bind the service in another activity in another application, where the same interface is available: bindService(new Intent("ch.ifi.csg.games4blue.gamebase.api.ComService"), conn, Context.BIND_AUTO_CREATE); and private ServiceConnection conn = new ServiceConnection() { @Override public void onServiceConnected(ComponentName name, IBinder service) { Log.i("INFO", "Service bound " + name); comService = ((IComService.IServiceBinder)service).getService(); serviceHandler.sendEmptyMessage(0); } @Override public void onServiceDisconnected(ComponentName arg0) { Log.i("INFO", "Service Unbound "); } }; but the line comService = ((IComService.IServiceBinder)service).getService(); always throws a 05-02 22:12:55.922: ERROR/AndroidRuntime(622): java.lang.ClassCastException: android.os.BinderProxy I can't explain why, I followed the app sample on http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/app/LocalServiceBinding.html Any hints would be nice!

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  • Factory Method Implementation

    - by cedar715
    I was going through the 'Factory method' pages in SO and had come across this link. And this comment. The example looked as a variant and thought to implement in its original way: to defer instantiation to subclasses... Here is my attempt. Does the following code implements the Factory pattern of the example specified in the link? Please validate and suggest if this has to undergo any re-factoring. public class ScheduleTypeFactoryImpl implements ScheduleTypeFactory { @Override public IScheduleItem createLinearScheduleItem() { return new LinearScheduleItem(); } @Override public IScheduleItem createVODScheduleItem() { return new VODScheduleItem(); } } public class UseScheduleTypeFactory { public enum ScheduleTypeEnum { CableOnDemandScheduleTypeID, BroadbandScheduleTypeID, LinearCableScheduleTypeID, MobileLinearScheduleTypeID } public static IScheduleItem getScheduleItem(ScheduleTypeEnum scheduleType) { IScheduleItem scheduleItem = null; ScheduleTypeFactory scheduleTypeFactory = new ScheduleTypeFactoryImpl(); switch (scheduleType) { case CableOnDemandScheduleTypeID: scheduleItem = scheduleTypeFactory.createVODScheduleItem(); break; case BroadbandScheduleTypeID: scheduleItem = scheduleTypeFactory.createVODScheduleItem(); break; case LinearCableScheduleTypeID: scheduleItem = scheduleTypeFactory.createLinearScheduleItem(); break; case MobileLinearScheduleTypeID: scheduleItem = scheduleTypeFactory.createLinearScheduleItem(); break; default: break; } return scheduleItem; } }

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  • WPF - Adding ContentControl to Custom Canvas

    - by Alp Hancioglu
    I have a custom DrawingCanvas which is inherited from Canvas. When I add a ContentControl to DrawingCanvas with the following code nothing shows up. GraphicsRectangle rect = new GraphicsRectangle(0, 0, 200, 200, 5, Colors.Blue); DrawingContainer host = new DrawingContainer(rect); ContentControl control = new ContentControl(); control.Width = 200; control.Height = 200; DrawingCanvas.SetLeft(control, 100); DrawingCanvas.SetTop(control, 100); control.Style = Application.Current.Resources["DesignerItemStyle"] as Style; control.Content = host; drawingCanvas.Children.Add(control); GraphicsRectangle is a DrawingVisual and the constructor above draws a Rect with (0,0) top left point and length of 200 to the drawingContext of GraphicsRectangle. DrawingContainer is a FrameworkElement and it has one child, which is rect above, given with constructor. DrawingContainer implements GetVisualChild and VisualChildrenCount override methods. At last, Content property of ContentControl is set to the DrawingContainer to be able to show the DrawingVisual's content. When I add the created ContentControl to a regular Canvas, control is showed correctly. I guess the reason is that DrawingCanvas doesn't implement ArrangeOverride method. It only implements MeasureOverride method. Also DrawingContainer doesn't implement Measure and Arrange override methods. Any ideas?

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  • What is the best way to translate this recursive python method into Java?

    - by Simucal
    In another question I was provided with a great answer involving generating certain sets for the Chinese Postman Problem. The answer provided was: def get_pairs(s): if not s: yield [] else: i = min(s) for j in s - set([i]): for r in get_pairs(s - set([i, j])): yield [(i, j)] + r for x in get_pairs(set([1,2,3,4,5,6])): print x This will output the desire result of: [(1, 2), (3, 4), (5, 6)] [(1, 2), (3, 5), (4, 6)] [(1, 2), (3, 6), (4, 5)] [(1, 3), (2, 4), (5, 6)] [(1, 3), (2, 5), (4, 6)] [(1, 3), (2, 6), (4, 5)] [(1, 4), (2, 3), (5, 6)] [(1, 4), (2, 5), (3, 6)] [(1, 4), (2, 6), (3, 5)] [(1, 5), (2, 3), (4, 6)] [(1, 5), (2, 4), (3, 6)] [(1, 5), (2, 6), (3, 4)] [(1, 6), (2, 3), (4, 5)] [(1, 6), (2, 4), (3, 5)] [(1, 6), (2, 5), (3, 4)] This really shows off the expressiveness of Python because this is almost exactly how I would write the pseudo-code for the algorithm. I especially like the usage of yield and and the way that sets are treated as first class citizens. However, there in lies my problem. What would be the best way to: 1.Duplicate the functionality of the yield return construct in Java? Would it instead be best to maintain a list and append my partial results to this list? How would you handle the yield keyword. 2.Handle the dealing with the sets? I know that I could probably use one of the Java collections which implements that implements the Set interface and then using things like removeAll() to give me a set difference. Is this what you would do in that case? Ultimately, I'm looking to reduce this method into as concise and straightforward way as possible in Java. I'm thinking the return type of the java version of this method will likely return a list of int arrays or something similar. How would you handle the situations above when converting this method into Java?

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  • Help regarding composite pattern with hibernate

    - by molleman
    Hello, So i am stuck, i am creating a gwt web application, i will be using a tree(gwt Tree and TreeItems) structure to show a list of folders(class Folder) and files(class FileLocation), the folder and filelocation class will all implement a Hierarchy interface basing the classes on the composite pattern. but i am using hibernate to store my data , and i am using annotations for the mapping of the data to the database. my trouble is i do not know how to annotate my interface. have any of you guys used the composite pattern while persisting the data with hibernate public interface Hierarchy(){ // a few abstract methods that will be implemented by the sub classes } @Entity @Table() public class Folder extends Hierarchy implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "folder_id", updatable = false, nullable = false) private int id; @OneToMany(cascade = CascadeType.ALL,fetch = FetchType.EAGER) @JoinTable(name = "FOLDER_FILELOCATION", joinColumns = { @JoinColumn(name = "folder_id") }, inverseJoinColumns = { @JoinColumn(name = "file_information_id") }) private List<Hierarchy> children = new ArrayList<Hierarchy>() ; @Column(name = "folder_name") private String folderName; @Column(name = "tree_item") private TreeItem item; @Column (name = "parent") private Hierarchy parent; @Entity @Table(name = "FILE_INFORMATION_TABLE") public class FileInformation extends Hierarchy implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "file_information_id", updatable = false, nullable = false) private int fiId; @Column (name = "location") private String location; @Column(name = "tree_item") private TreeItem item; @Column (name = "parent") private Hierarchy parent;

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  • Convert IDispatch* to a string?

    - by Rob
    I am converting an old VB COM object (which I didn't write) to C++ using ATL. One of the methods, according to the IDL, takes an IDispatch* as a parameter and the documentation and samples for this method claim that you can pass either a string (which is the progid of an object that will be created and used by the control) or an IDispatch* to an object that has already been created. How on earth do I implement this in ATL? For example, the IDL: [id(1)] HRESULT Test(IDispatch* obj); The samples (which are all JScript): obj.Test("foo.bar"); or var someObject = new ActiveXObject("foo.bar"); obj.Test(someObject); To make matters even more bizarre the actual VB code that implements this method actually declares the 'obj' parameter as a string! However, it all seems to work. Can you even pass a string to a COM method that takes an IDispatch*? If so, can I determine that the IDispatch* is actually a string in my C++ ATL code? Even better, if it's an IDispatch that implements a specific interface I will want to call methods on it, or instantiate an object if it's a string. Any ideas welcome!

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  • How to implement IEquatable<T> when mutable fields are part of the equality - Problem with GetHashCo

    - by Shimmy
    Hello! I am using Entity Framework in my application. I implemented with the partial class of an entity the IEquatable<T> interface: Partial Class Address : Implements IEquatable(Of Address) 'Other part generated Public Overloads Function Equals(ByVal other As Address) As Boolean _ Implements System.IEquatable(Of Address).Equals If ReferenceEquals(Me, other) Then Return True Return AddressId = other.AddressId End Function Public Overrides Function Equals(ByVal obj As Object) As Boolean If obj Is Nothing Then Return MyBase.Equals(obj) If TypeOf obj Is Address Then Return Equals(DirectCast(obj, Address)) Else Return False End Function Public Overrides Function GetHashCode() As Integer Return AddressId.GetHashCode End Function End Class Now in my code I use it this way: Sub Main() Using e As New CompleteKitchenEntities Dim job = e.Job.FirstOrDefault Dim address As New Address() job.Addresses.Add(address) Dim contains1 = job.Addresses.Contains(address) 'True e.SaveChanges() Dim contains2 = job.Addresses.Contains(address) 'False 'The problem is that I can't remove it: Dim removed = job.Addresses.Remoeve(address) 'False End Using End Sub Note (I checked in the debugger visualizer) that the EntityCollection class stores its entities in HashSet so it has to do with the GetHashCode function, I want it to depend on the ID so entities are compared by their IDs. The problem is that when I hit save, the ID changes from 0 to its db value. So the question is how can I have an equatable object, being properly hashed. Please help me find what's wrong in the GetHashCode function (by ID) and what can I change to make it work. Thanks a lot.

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  • Are there scenarios where the ViewModel needs to invoke methods on the View w.r.t. MVVM in WPF?

    - by Gishu
    As per the pattern, the ViewModel exposes Properties(with change notification) and Commands (to notify the VM of user actions) that the View binds to. The only communication that flows from the VM to the View is the property change notifications (so that the View can refresh itself with updated data). In MVP or PresentationModel form of the pattern (if I'm not mistaken), the View implements a plain vanilla interface (consisting of methods, properties and/or events). With MVVM, it feels methods on the IView have been outlawed (along with IView itself). One scenario I could think of was to set the focus to a certain control in the View. (When the user does ActionX, the focus should immediately be set to FieldY). In MVP, I'd write this as IView.ActivateField(NameConstant), which the presenter or PM would invoke. In MVVM, this seems to be a fringe case that needs a workaround / little bit of code-behind. The VM implements an ActiveField Property, which it sets to NameConstant. The view picks up the change notification event and in a code-behind event handler, activates the Name control. Is the above just an exception to the norm? Or are there other such scenarios, where the VM needs to invoke a method on the View ?

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  • Hibernate Auto-Increment Setup

    - by dharga
    How do I define an entity for the following table. I've got something that isn't working and I just want to see what I'm supposed to do. USE [BAMPI_TP_dev] GO SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO SET ANSI_PADDING ON GO CREATE TABLE [dbo].[MemberSelectedOptions]( [OptionId] [int] NOT NULL, [SeqNo] [smallint] IDENTITY(1,1) NOT NULL, [OptionStatusCd] [char](1) NULL ) ON [PRIMARY] GO SET ANSI_PADDING OFF This is what I have already that isn't working. @Entity @Table(schema="dbo", name="MemberSelectedOptions") public class MemberSelectedOption extends BampiEntity implements Serializable { @Embeddable public static class MSOPK implements Serializable { private static final long serialVersionUID = 1L; @Column(name="OptionId") int optionId; @GeneratedValue(strategy=GenerationType.IDENTITY) @Column(name="SeqNo", unique=true, nullable=false) BigDecimal seqNo; //Getters and setters here... } private static final long serialVersionUID = 1L; @EmbeddedId MSOPK pk = new MSOPK(); @Column(name="OptionStatusCd") String optionStatusCd; //More Getters and setters here... } I get the following ST. [5/25/10 15:49:40:221 EDT] 0000003d JDBCException E org.slf4j.impl.JCLLoggerAdapter error Cannot insert explicit value for identity column in table 'MemberSelectedOptions' when IDENTITY_INSERT is set to OFF. [5/25/10 15:49:40:221 EDT] 0000003d AbstractFlush E org.slf4j.impl.JCLLoggerAdapter error Could not synchronize database state with session org.hibernate.exception.SQLGrammarException: could not insert: [com.bob.proj.ws.model.MemberSelectedOption] at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:90) at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66) at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2285) at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2678) at org.hibernate.action.EntityInsertAction.execute(EntityInsertAction.java:79) at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:279) at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:263) at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:167) at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321) at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:50) at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1028) at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:366) at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:137) at com.bcbst.bamp.ws.dao.MemberSelectedOptionDAOImpl.saveMemberSelectedOption(MemberSelectedOptionDAOImpl.java:143) at com.bcbst.bamp.ws.common.AlertReminder.saveMemberSelectedOptions(AlertReminder.java:76) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)

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  • [hibernate - jpa] @CollectionOfElements without create the apposite table

    - by blow
    Hi all. I have this: Municipality class @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; @CollectionOfElements private List<Address> addressList; public Municipality() { } ... Address class @Embeddable public class Address implements Serializable { @ManyToOne(fetch=FetchType.LAZY) @Cascade(CascadeType.SAVE_UPDATE) private Municipality municipality; @Column(length=45) private String address; public Address() { } ... Address is embedded in another class Person. When i save an instance of Person, hibernate create 3 tables: PERSON, MUNICIPALITY and MUNICIPALITY_ADDRESSLIST. MUNICIPALITY_ADDRESSLIST contains 2 fields: MUNICIPALITY_ID (FK) and STREET. I don't want this table, i only want the ID of table MUNICIPALITY into table PERSON(that embeds Address), what should i do? I tried to add @JoinTable in Municipality entity like this: @CollectionOfElements @JoinTable(name="person") private List<Address> addressList; It partially worked, but i cant choose the column name of table PERSON that contains ID of the table MUNICIPALITY, it is, by hibernate choose, simply "MUNICIPALITY_ID"... Thbaks.

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  • How to use a int2 database-field as a boolean in Java using JPA/Hibernate

    - by mg
    Hello... I write an application based on an already existing database (postgreSQL) using JPA and Hibernate. There is a int2-column (activeYN) in a table, which is used as a boolean (0 = false (inactive), not 0 = true (active)). In the Java application i want to use this attribute as a boolean. So i defined the attribute like this: @Entity public class ModelClass implements Serializable { /*..... some Code .... */ private boolean active; @Column(name="activeYN") public boolean isActive() { return this.active; } /* .... some other Code ... */ } But there ist an exception because Hibernate expects an boolean database-field and not an int2. Can i do this mapping i any way while using a boolean in java?? I have a possible solution for this, but i don't really like it: My "hacky"-solution is the following: @Entity public class ModelClass implements Serializable { /*..... some Code .... */ private short active_USED_BY_JPA; //short because i need int2 /** * @Deprecated this method is only used by JPA. Use the method isActive() */ @Column(name="activeYN") public short getActive_USED_BY_JPA() { return this.active_USED_BY_JPA; } /** * @Deprecated this method is only used by JPA. * Use the method setActive(boolean active) */ public void setActive_USED_BY_JPA(short active) { this.active_USED_BY_JPA = active; } @Transient //jpa will ignore transient marked methods public boolean isActive() { return getActive_USED_BY_JPA() != 0; } @Transient public void setActive(boolean active) { this.setActive_USED_BY_JPA = active ? -1 : 0; } /* .... some other Code ... */ } Are there any other solutions for this problem? The "hibernate.hbm2ddl.auto"-value in the hibernate configuration is set to "validate". (sorry, my english is not the best, i hope you understand it anyway)..

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  • Java method keyword "final" and its use

    - by Lukas Eder
    When I create complex type hierarchies (several levels, several types per level), I like to use the final keyword on methods implementing some interface declaration. An example: interface Garble { int zork(); } interface Gnarf extends Garble { /** * This is the same as calling {@link #zblah(0)} */ int zblah(); int zblah(int defaultZblah); } And then abstract class AbstractGarble implements Garble { @Override public final int zork() { ... } } abstract class AbstractGnarf extends AbstractGarble implements Gnarf { // Here I absolutely want to fix the default behaviour of zblah // No Gnarf shouldn't be allowed to set 1 as the default, for instance @Override public final int zblah() { return zblah(0); } // This method is not implemented here, but in a subclass @Override public abstract int zblah(int defaultZblah); } I do this for several reasons: It helps me develop the type hierarchy. When I add a class to the hierarchy, it is very clear, what methods I have to implement, and what methods I may not override (in case I forgot the details about the hierarchy) I think overriding concrete stuff is bad according to design principles and patterns, such as the template method pattern. I don't want other developers or my users do it. So the final keyword works perfectly for me. My question is: Why is it used so rarely in the wild? Can you show me some examples / reasons where final (in a similar case to mine) would be very bad?

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  • SpringMvc Annotations for DAO interface and DAO implementation

    - by dev_darin
    I would like to know if I am annotating these classes correctly, since I am new to the annotations: Country.java @Component public class Country { private int countryId; private String countryName; private String countryCode; /** * No args constructor */ public Country() { } /** * @param countryId * @param countryName * @param countryCode */ public Country(int countryId, String countryName, String countryCode) { this.countryId = countryId; this.countryName = countryName; this.countryCode = countryCode; } //getters and setters } CountryDAO.java @Repository public interface CountryDAO { public List<Country> getCountryList(); public void saveCountry(Country country); public void updateCountry(Country country); } JdbcCountryDAO.java @Component public class JdbcCountryDAO extends JdbcDaoSupport implements CountryDAO{ private final Logger logger = Logger.getLogger(getClass()); @Autowired public List<Country> getCountryList() { int countryId = 6; String countryCode = "AI"; logger.debug("In getCountryList()"); String sql = "SELECT * FROM TBLCOUNTRY WHERE countryId = ? AND countryCode = ?"; logger.debug("Executing getCountryList String "+sql); Object[] parameters = new Object[] {countryId, countryCode}; logger.info(sql); //List<Country> countryList = getJdbcTemplate().query(sql,new CountryMapper()); List<Country> countryList = getJdbcTemplate().query(sql, parameters,new CountryMapper()); return countryList; } CountryManagerIFace.java @Repository public interface CountryManagerIFace extends Serializable{ public void saveCountry(Country country); public List<Country> getCountries(); } CountryManager.java @Component public class CountryManager implements CountryManagerIFace{ @Autowired private CountryDAO countryDao; public void saveCountry(Country country) { countryDao.saveCountry(country); } public List<Country> getCountries() { return countryDao.getCountryList(); } public void setCountryDao(CountryDAO countryDao){ this.countryDao = countryDao; } }

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  • Strange GWT serialization exception when overiding method of serialized object

    - by Flueras Bogdan
    Hi there! I have a GWT serializable class, lets call it Foo. Foo implements IsSerializable, has primitive and serializable members as well as other transient members and a no-arg constructor. class Foo implements IsSerializable { // transient members // primitive members public Foo() {} public void bar() {} } Also a Service which handles RPC comunication. // server code public interface MyServiceImpl { public void doStuff(Foo foo); } public interface MyServiceAsync { void doStuff(Foo foo, AsyncCallback<Void> async); } How i use this: private MyServiceAsync myService = GWT.create(MyService.class); Foo foo = new Foo(); ... AsyncCallback callback = new new AsyncCallback {...}; myService.doStuff(foo, callback); In the above case the code is running, and the onSuccess() method of callback instance gets executed. But when I override the bar() method on foo instance like this: Foo foo = new Foo() { public void bar() { //do smthng different } } AsyncCallback callback = new new AsyncCallback {...}; myService.doStuff(foo, callback); I get the GWT SerializationException. Please enlighten me, because I really don't understand why.

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  • How to find the first declaring method for a reference method

    - by Oliver Gierke
    Suppose you have a generic interface and an implementation: public interface MyInterface<T> { void foo(T param); } public class MyImplementation<T> implements MyInterface<T> { void foo(T param) { } } These two types are frework types. In the next step I want allow users to extend that interface as well as redeclare foo(T param) to maybe equip it with further annotations. public interface MyExtendedInterface extends MyInterface<Bar> { @Override void foo(Bar param); // Further declared methods } I create an AOP proxy for the extended interface and intercept especially the calls to furtherly declared methods. As foo(…) is no redeclared in MyExtendedInterface I cannot execute it by simply invoking MethodInvocation.proceed() as the instance of MyImplementation only implements MyInterface.foo(…) and not MyExtendedInterface.foo(…). So is there a way to get access to the method that declared a method initially? Regarding this example is there a way to find out that foo(Bar param) was declared in MyInterface originally and get access to the accoriding Method instance? I already tried to scan base class methods to match by name and parameter types but that doesn't work out as generics pop in and MyImplementation.getMethod("foo", Bar.class) obviously throws a NoSuchMethodException. I already know that MyExtendedInterface types MyInterface to Bar. So If I could create some kind of "typed view" on MyImplementation my math algorithm could work out actually.

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  • Deleting objects with FK constraints in Spring/Hibernate

    - by maxdj
    This seems like such a simple scenario to me, yet I cannot for the life of my find a solution online or in print. I have several objects like so (trimmed down): @Entity public class Group extends BaseObject implements Identifiable<Long> { private Long id; private String name; private Set<HiringManager> managers = new HashSet<HiringManager>(); private List<JobOpening> jobs; @ManyToMany(fetch=FetchType.EAGER) @JoinTable( name="group_hiringManager", joinColumns=@JoinColumn(name="group_id"), inverseJoinColumns=@JoinColumn(name="hiringManager_id") ) public Set<HiringManager> getManagers() { return managers; } @OneToMany(mappedBy="group", fetch=FetchType.EAGER) public List<JobOpening> getJobs() { return jobs; } } @Entity public class JobOpening extends BaseObject implements Identifiable<Long> { private Long id; private String name; private Group group; @ManyToOne @JoinColumn(name="group_id", updatable=false, nullable=true) public Group getGroup() { return group; } } @Entity public class HiringManager extends User { @ManyToMany(mappedBy="managers", fetch=FetchType.EAGER) public Set<Group> getGroups() { return groups; } } Say I want to delete a Group object. Now there are dependencies on it in the JobOpening table and in the group_hiringManager table, which cause the delete function to fail. I don't want to cascade the delete, because the managers have other groups, and the jobopenings can be groupless. I have tried overriding the remove() function of my GroupManager to remove the dependencies, but it seems like no matter what I do they persist, and the delete fails! What is the right way to remove this object?

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

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

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  • Serialize Forms into memory

    - by serhio
    Background: In a desktop MDI application we have a lot of forms. Task: Save the controls contents of closed forms(textbox texts, checkbox checks etc). Limitations: A saved form for (DB/Windows) user? For (DB/Windows) group of users? Both variants may be possible. Question: a) What is the best way? b) if I want do not use files, how to serialize the form into a MemoryStream and then recuperate it if the opening form was been once opened and serialized? StartingPoint: Implemented a form that implements ISerializable. Deserialize the form on opening, serialize onclosing: Public Sub GetObjectData(ByVal info As System.Runtime.Serialization.SerializationInfo, ByVal context As System.Runtime.Serialization.StreamingContext) Implements System.Runtime.Serialization.ISerializable.GetObjectData info.AddValue("tbxExportFolder", tbxExportFolder.Text, GetType(String)) info.AddValue("cbxCheckAliasUnicity", cbxCheckAliasUnicity.Checked, GetType(Boolean)) End Sub Public Sub New(ByVal info As SerializationInfo, ByVal context As StreamingContext) Me.New() Me.tbxExportFolder.Text = info.GetString("tbxExportFolder") Me.cbxCheckAliasUnicity.Checked = info.GetBoolean("cbxCheckAliasUnicity") End Sub Private Sub SerializeMe() Dim binFormatter As New Formatters.Binary.BinaryFormatter Dim fileStream As New FileStream(SerializedFilename, FileMode.Create) Try binFormatter.Serialize(fileStream, Me) Catch Throw Finally fileStream.Close() End Try End Sub Protected Overrides Sub OnClosing(ByVal e As System.ComponentModel.CancelEventArgs) SerializeMe() MyBase.OnClosing(e) End Sub

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  • ibatis throwing NullPointerException

    - by Prashant P
    i am trying to test ibatis with DB. I get NullPointerException. Below are the class and ibatis bean config, <select id="getByWorkplaceId" parameterClass="java.lang.Integer" resultMap="result"> select * from WorkDetails where workplaceCode=#workplaceCode# </select> <select id="getWorkplace" resultClass="com.ibatis.text.WorkDetails"> select * from WorkDetails </select> POJO public class WorkplaceDetail implements Serializable { private static final long serialVersionUID = -6760386803958725272L; private int code; private String plant; private String compRegNum; private String numOfEmps; private String typeIndst; private String typeProd; private String note1; private String note2; private String note3; private String note4; private String note5; } DAOimplementation public class WorkplaceDetailImpl implements WorkplaceDetailsDAO { private SqlMapClient sqlMapClient; public void setSqlMapClient(SqlMapClient sqlMapClient) { this.sqlMapClient = sqlMapClient; } @Override public WorkplaceDetail getWorkplaceDetail(int code) { WorkplaceDetail workplaceDetail=new WorkplaceDetail(); try{ **workplaceDetail= (WorkplaceDetail) this.sqlMapClient.queryForObject("workplaceDetail.getByWorkplaceId", code);** }catch (SQLException sqlex){ sqlex.printStackTrace(); } return workplaceDetail; } TestCode public class TestDAO { public static void main(String args[]) throws Exception{ WorkplaceDetail wd = new WorkplaceDetail(126, "Hoonkee", "1234", "22", "Service", "Tele", "hsgd","hsgd","hsgd","hsgd","hsgd"); WorkplaceDetailImpl impl= new WorkplaceDetailImpl(); **impl.getWorkplaceDetail(wd.getCode());** impl.saveOrUpdateWorkplaceDetails(wd); System.out.println("dhsd"+impl); } } I want to select and insert. I have marked as ** ** as a point of exception in above code Exception in thread "main" java.lang.NullPointerException at com.ibatis.text.WorkplaceDetailImpl.getWorkplaceDetail(WorkplaceDetailImpl.java:19) at com.ibatis.text.TestDAO.main(TestDAO.java:11)

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  • EJB and JPA and @OneToMany - Transaction too long?

    - by marioErr
    Hello. I'm using EJB and JPA, and when I try to access PhoneNumber objects in phoneNumbers attribute of Contact contact, it sometimes take several minutes for it to actually return data. It just returns no phoneNumbers, not even null, and then, after some time, when i call it again, it magically appears. This is how I access data: for (Contact c : contactFacade.findAll()) { System.out.print(c.getName()+" "+c.getSurname()+" : "); for (PhoneNumber pn : c.getPhoneNumbers()) { System.out.print(pn.getNumber()+" ("+pn.getDescription()+"); "); } } I'm using facade session ejb generated by netbeans (basic CRUD methods). It always prints correct name and surname, phonenumbers and description are only printed after some time (it varies) from creating it via facade. I'm guessing it has something to do with transactions. How to solve this? These are my JPA entities: contact @Entity public class Contact implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; private String name; private String surname; @OneToMany(cascade = CascadeType.REMOVE, mappedBy = "contact") private Collection<PhoneNumber> phoneNumbers = new ArrayList<PhoneNumber>(); phonenumber @Entity public class PhoneNumber implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; private String number; private String description; @ManyToOne() @JoinColumn(name="CONTACT_ID") private Contact contact;

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