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  • Is it important to dispose SolidBrush and Pen?

    - by Joe
    I recently came across this VerticalLabel control on CodeProject. I notice that the OnPaint method creates but doesn't dispose Pen and SolidBrush objects. Does this matter, and if so how can I demonstrate whatever problems it can cause? EDIT This isn't a question about the IDisposable pattern in general. I understand that callers should normally call Dispose on any class that implements IDisposable. What I want to know is what problems (if any) can be expected when GDI+ object are not disposed as in the above example. It's clear that, in the linked example, OnPaint may be called many times before the garbage collector kicks in, so there's the potential to run out of handles. However I suspect that GDI+ internally reuses handles in some circumstances (for example if you use a pen of a specific color from the Pens class, it is cached and reused). What I'm trying to understand is whether code like that in the linked example will be able to get away with neglecting to call Dispose. And if not, to see a sample that demonstrated what problems it can cause. I should add that I have very often (including the OnPaint documentation on MSDN) seen WinForms code samples that fail to dispose GDI+ objects.

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  • volatile keyword seems to be useless?

    - by Finbarr
    import java.util.concurrent.CountDownLatch; import java.util.concurrent.atomic.AtomicInteger; public class Main implements Runnable { private final CountDownLatch cdl1 = new CountDownLatch(NUM_THREADS); private volatile int bar = 0; private AtomicInteger count = new AtomicInteger(0); private static final int NUM_THREADS = 25; public static void main(String[] args) { Main main = new Main(); for(int i = 0; i < NUM_THREADS; i++) new Thread(main).start(); } public void run() { int i = count.incrementAndGet(); cdl1.countDown(); try { cdl1.await(); } catch (InterruptedException e1) { e1.printStackTrace(); } bar = i; if(bar != i) System.out.println("Bar not equal to i"); else System.out.println("Bar equal to i"); } } Each Thread enters the run method and acquires a unique, thread confined, int variable i by getting a value from the AtomicInteger called count. Each Thread then awaits the CountDownLatch called cdl1 (when the last Thread reaches the latch, all Threads are released). When the latch is released each thread attempts to assign their confined i value to the shared, volatile, int called bar. I would expect every Thread except one to print out "Bar not equal to i", but every Thread prints "Bar equal to i". Eh, wtf does volatile actually do if not this?

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  • How do I implement a listener pattern over RMI using Spring?

    - by predhme
    So here is a generalized version of our application desgin: @Controller public class MyController { @Autowired private MyServiceInterface myServiceInterface; @RequestMapping("/myURL") public @ResponseBody String doSomething() { MyListenerInterface listener = new MyListenerInterfaceImpl(); myServiceInterface.doThenCallListener(listener); // do post stuff } } public interface MyListenerInterface { public void callA(); public void callB(); } public class MyListenerInterfaceImpl implements MyListenerInterface { // ... omitted for clarity } public interface MyServiceInterface { public void doThenCallListener(MyListenerInterface listener); } public class MyServiceImpl { public void doThenCallListener(MyListenerInterface listener) { // do stuff listener.callA(); } } Basically I have a controller that is being called via AJAX in which I am looking to return a response as a string. However, I need to make a call to the backend (MyServiceInterface). That guy is exposed through RMI by using Spring (man that was easy). But the service method as described requires a listener to be registered for invokation completion purposes. So what I assume I need to achieve is transparently to the backend make it so that when the listener methods are called, really the call is going over RMI. I would have thought Spring would have a simple way to wrap a POJO (not a service singleton) with RMI calls. I looked through their documentation but they had nothing besides exposing services via RMI. Could someone point me in the right direction?

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  • Problem when trying to connect to a desktop server from android on wifi

    - by thiagolee
    Hello, I am trying to send a file from the phone running Android 1.5 to a server on a desktop. I wrote some code, which works on emulator, but on the phone it doesn't. I'm connecting to the network through WiFi. It works, I can access the internet through my phone and I've configured my router. The application stops when I'm trying to connect. I have the permissions. Someone have any ideas, below is my code. Running on Android package br.ufs.reconhecimento; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.net.Socket; import android.app.Activity; import android.app.AlertDialog; import android.content.DialogInterface; import android.content.Intent; import android.os.Bundle; import android.util.Log; import android.view.View; import android.view.View.OnClickListener; import android.widget.EditText; import android.widget.ImageButton; /** * Sample code that invokes the speech recognition intent API. */ public class Reconhecimento extends Activity implements OnClickListener { static final int VOICE_RECOGNITION_REQUEST_CODE = 1234; static final String LOG_VOZ = "UFS-Reconhecimento"; final int INICIAR_GRAVACAO = 01; int porta = 5158; // Porta definida no servidor int tempoEspera = 1000; String ipConexao = "172.20.0.189"; EditText ipEdit; /** * Called with the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Inflate our UI from its XML layout description. setContentView(R.layout.main); // Get display items for later interaction ImageButton speakButton = (ImageButton) findViewById(R.id.btn_speak); speakButton.setPadding(10, 10, 10, 10); speakButton.setOnClickListener(this); //Alerta para o endereço IP AlertDialog.Builder alerta = new AlertDialog.Builder(this); alerta.setTitle("IP");//+mainWifi.getWifiState()); ipEdit = new EditText(this); ipEdit.setText(ipConexao); alerta.setView(ipEdit); alerta.setMessage("Por favor, Confirme o endereço IP."); alerta.setPositiveButton("OK", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { ipConexao = ipEdit.getText().toString(); Log.d(LOG_VOZ, "Nova Atribuição do Endreço IP: " + ipConexao); } }); alerta.create(); alerta.show(); } /** * Handle the click on the start recognition button. */ public void onClick(View v) { if (v.getId() == R.id.btn_speak) { //startVoiceRecognitionActivity(); Log.d(LOG_VOZ, "Iniciando a próxima tela"); Intent recordIntent = new Intent(this, GravacaoAtivity.class); Log.d(LOG_VOZ, "Iniciando a tela (instancia criada)"); startActivityForResult(recordIntent, INICIAR_GRAVACAO); Log.d(LOG_VOZ, "Gravação iniciada ..."); } } /** * Handle the results from the recognition activity. */ @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { Log.d(LOG_VOZ, "Iniciando onActivityResult()"); if (requestCode == INICIAR_GRAVACAO && resultCode == RESULT_OK) { String path = data.getStringExtra(GravacaoAtivity.RETORNO); conexaoSocket(path); } else Log.e(LOG_VOZ, "Resultado Inexperado ..."); } private void conexaoSocket(String path) { Socket socket = SocketOpener.openSocket(ipConexao, porta, tempoEspera); if(socket == null) return; try { DataOutputStream conexao = new DataOutputStream(socket.getOutputStream()); Log.d(LOG_VOZ, "Acessando arquivo ..."); File file = new File(path); DataInputStream arquivo = new DataInputStream(new FileInputStream(file)); Log.d(LOG_VOZ, "Iniciando Transmissão ..."); conexao.writeLong(file.length()); for(int i = 0; i < file.length(); i++) conexao.writeByte(arquivo.readByte()); Log.d(LOG_VOZ, "Transmissão realizada com sucesso..."); Log.d(LOG_VOZ, "Fechando a conexão..."); conexao.close(); socket.close(); Log.d(LOG_VOZ, "============ Processo finalizado com Sucesso =============="); } catch (IOException e) { Log.e(LOG_VOZ, "Erro ao fazer a conexão via Socket. " + e.getMessage()); // TODO Auto-generated catch block } } } class SocketOpener implements Runnable { private String host; private int porta; private Socket socket; public SocketOpener(String host, int porta) { this.host = host; this.porta = porta; socket = null; } public static Socket openSocket(String host, int porta, int timeOut) { SocketOpener opener = new SocketOpener(host, porta); Thread t = new Thread(opener); t.start(); try { t.join(timeOut); } catch(InterruptedException e) { Log.e(Reconhecimento.LOG_VOZ, "Erro ao fazer o join da thread do socket. " + e.getMessage()); //TODO: Mensagem informativa return null; } return opener.getSocket(); } public void run() { try { socket = new Socket(host, porta); }catch(IOException e) { Log.e(Reconhecimento.LOG_VOZ, "Erro na criação do socket. " + e.getMessage()); //TODO: Mensagem informativa } } public Socket getSocket() { return socket; } } Running on the desktop Java: import java.io.BufferedReader; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStreamReader; import java.net.ServerSocket; import java.net.Socket; public class ServidorArquivo { private static int porta = 5158; static String ARQUIVO = "voz.amr"; /** * Caminho que será gravado o arquivo de audio */ static String PATH = "/home/iade/Trabalho/lib/"; public static void main(String[] args) { int i = 1; try { System.out.println("Iniciando o Servidor Socket - Android."); ServerSocket s = new ServerSocket(porta); System.out.println("Servidor Iniciado com Sucesso..."); System.out.println("Aguardando conexões na porta: " + porta); while(true) { Socket recebendo = s.accept(); System.out.println("Aceitando conexão de nº " + i); new ThreadedHandler(recebendo).start(); i++; } } catch (Exception e) { System.out.println("Erro: " + e.getMessage()); e.printStackTrace(); } } } class ThreadedHandler extends Thread { private Socket socket; public ThreadedHandler(Socket so) { socket = so; } public void run() { DataInputStream entrada = null; DataOutputStream arquivo = null; try { entrada = new DataInputStream(socket.getInputStream()); System.out.println("========== Iniciando a leitura dos dados via Sockets =========="); long tamanho = entrada.readLong(); System.out.println("Tamanho do vetor " + tamanho); File file = new File(ServidorArquivo.PATH + ServidorArquivo.ARQUIVO); if(!file.exists()) file.createNewFile(); arquivo = new DataOutputStream(new FileOutputStream(file)); for(int j = 0; j < tamanho; j++) { arquivo.write(entrada.readByte()); } System.out.println("========== Dados recebidos com sucesso =========="); } catch (Exception e) { System.out.println("Erro ao tratar do socket: " + e.getMessage()); e.printStackTrace(); } finally { System.out.println("**** Fechando as conexões ****"); try { entrada.close(); socket.close(); arquivo.close(); } catch (IOException e) { System.out.println("Erro ao fechar conex&#65533;es " + e.getMessage()); e.printStackTrace(); } } System.out.println("============= Fim da Gravação ==========="); // tratar o arquivo String cmd1 = "ffmpeg -i voz.amr -ab 12288 -ar 16000 voz.wav"; String cmd2 = "soundstretch voz.wav voz2.wav -tempo=100"; String dir = "/home/iade/Trabalho/lib"; File workDir = new File(dir); File f1 = new File(dir+"/voz.wav"); File f2 = new File(dir+"/voz2.wav"); f1.delete(); f2.delete(); try { executeCommand(cmd1, workDir); System.out.println("realizou cmd1"); executeCommand(cmd2, workDir); System.out.println("realizou cmd2"); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } private void executeCommand(String cmd1, File workDir) throws IOException, InterruptedException { String s; Process p = Runtime.getRuntime().exec(cmd1,null,workDir); int i = p.waitFor(); if (i == 0) { BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream())); // read the output from the command while ((s = stdInput.readLine()) != null) { System.out.println(s); } } else { BufferedReader stdErr = new BufferedReader(new InputStreamReader(p.getErrorStream())); // read the output from the command while ((s = stdErr.readLine()) != null) { System.out.println(s); } } } } Thanks in advance.

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  • @PrePersist with entity inheritance

    - by gerry
    I'm having some problems with inheritance and the @PrePersist annotation. My source code looks like the following: _the 'base' class with the annotated updateDates() method: @javax.persistence.Entity @Inheritance(strategy = InheritanceType.TABLE_PER_CLASS) public class Base implements Serializable{ ... @Id @GeneratedValue protected Long id; ... @Column(nullable=false) @Temporal(TemporalType.TIMESTAMP) private Date creationDate; @Column(nullable=false) @Temporal(TemporalType.TIMESTAMP) private Date lastModificationDate; ... public Date getCreationDate() { return creationDate; } public void setCreationDate(Date creationDate) { this.creationDate = creationDate; } public Date getLastModificationDate() { return lastModificationDate; } public void setLastModificationDate(Date lastModificationDate) { this.lastModificationDate = lastModificationDate; } ... @PrePersist protected void updateDates() { if (creationDate == null) { creationDate = new Date(); } lastModificationDate = new Date(); } } _ now the 'Child' class that should inherit all methods "and annotations" from the base class: @javax.persistence.Entity @NamedQueries({ @NamedQuery(name=Sensor.QUERY_FIND_ALL, query="SELECT s FROM Sensor s") }) public class Sensor extends Entity { ... // additional attributes @Column(nullable=false) protected String value; ... // additional getters, setters ... } If I store/persist instances of the Base class to the database, everything works fine. The dates are getting updated. But now, if I want to persist a child instance, the database throws the following exception: MySQLIntegrityConstraintViolationException: Column 'CREATIONDATE' cannot be null So, in my opinion, this is caused because in Child the method "@PrePersist protected void updateDates()" is not called/invoked before persisting the instances to the database. What is wrong with my code?

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  • Help in J2ME for creating image and parse it

    - by HAMED
    Can anyone tell me how i can parse a png image into many png images in J2ME??? for examole:I just wnat to have a source image 150*150 pixel and parse it to 10 image with 15*15 pixel. I write an elemantary code that have exeption. This is my code: public class HelloMIDlet extends MIDlet implements CommandListener { private boolean midletPaused = false; private Command exitCommand; private Form form; private StringItem stringItem; Image im , im2; Form form1 = null; public HelloMIDlet() { try { // create source image im = Image.createImage("/image1.JPG"); int height = im.getHeight() ; int width = im.getWidth() ; int x = 0 ; int y = 0 ; while ( y < height ){ while ( x < width ){ // create 15*15 pixel of source image im2 = im.createImage(im, x, y, 15, 15, Sprite.TRANS_NONE) ; x += 15 ; } y += 15 ; x = 0 ; } } catch (IOException ex) { ex.printStackTrace(); } } please help me to make it right....It's emergency! Thanks a lot guys...

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  • Working with complex objects in Prevayler commands

    - by alexantd
    The demos included in the Prevayler distribution show how to pass in a couple strings (or something simple like that) into a command constructor in order to create or update an object. The problem is that I have an object called MyObject that has a lot of fields. If I had to pass all of them into the CreateMyObject command manually, it would be a pain. So an alternative I thought of is to pass my business object itself into the command, but to hang onto a clone of it (keeping in mind that I can't store the BO directly in the command). Of course after executing this command, I would need to make sure to dispose of the original copy that I passed in. public class CreateMyObject implements TransactionWithQuery { private MyObject object; public CreateMyObject(MyObject business_obj) { this.object = (MyObject) business_obj.clone(); } public Object executeAndQuery(...) throws Exception { ... } } The Prevayler wiki says: Transactions can't carry direct object references (pointers) to business objects. This has become known as the baptism problem because it's a common beginner pitfall. Direct object references don't work because once a transaction has been serialized to the journal and then deserialized for execution its object references no longer refer to the intended objects - - any objects they may have referred to at first will have been copied by the serialization process! Therefore, a transaction must carry some kind of string or numeric identifiers for any objects it wants to refer to, and it must look up the objects when it is executed. I think by cloning the passed-in object I will be getting around the "direct object pointer" problem, but I still don't know whether or not this is a good idea...

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  • Improving field get and set performance with ASM

    - by ng
    I would like to avoid reflection in an open source project I am developing. Here I have classes like the following. public class PurchaseOrder { @Property private Customer customer; @Property private String name; } I scan for the @Property annotation to determine what I can set and get from the PurchaseOrder reflectively. There are many such classes all using java.lang.reflect.Field.get() and java.lang.reflect.Field.set(). Ideally I would like to generate for each property an invoker like the following. public interface PropertyAccessor<S, V> { public void set(S source, V value); public V get(S source); } Now when I scan the class I can create a static inner class of PurchaseOrder like so. static class customer_Field implements PropertyAccessor<PurchaseOrder, Customer> { public void set(PurchaseOrder order, Customer customer) { order.customer = customer; } public Customer get(PurchaseOrder order) { return order.customer; } } With these I totally avoid the cost of reflection. I can now set and get from my instances with native performance. Can anyone tell me how I would do this. A code example would be great. I have searched the net for a good example but can find nothing like this. The ASM examples are pretty poor also. The key here is that I have an interface that I can pass around. So I can have various implementations, perhaps one with Java Reflection as a default, one with ASM, and maybe one with Javassist? Any help would be greatly appreciated.

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  • WCF service reference namespace differs from original

    - by Thorarin
    I'm having a problem regarding namespaces used by my service references. I have a number of WCF services, say with the namespace MyCompany.Services.MyProduct (the actual namespaces are longer). As part of the product, I'm also providing a sample C# .NET website. This web application uses the namespace MyCompany.MyProduct. During initial development, the service was added as a project reference to the website and uses directly. I used a factory pattern that returns an object instance that implements MyCompany.Services.MyProduct.IMyService. So far, so good. Now I want to change this to use an actual service reference. After adding the reference and typing MyCompany.Services.MyProduct in the namespace textbox, it generates classes in the namespace MyCompany.MyProduct.MyCompany.Services.MyProduct. BAD! I don't want to have to change using directives in several places just because I'm using a proxy class. So I tried prepending the namespace with global::, but that is not accepted. Note that I hadn't even deleted the original assembly references yet, and "reuse types" is enabled, but no reusing was done, apparently. However, I don't want to keep the assembly references around in my sample website for it to work anyway. The only solution I've come up with so far is setting the default namespace for my web application to MyCompany (because it cannot be empty), and adding the service reference as Services.MyProduct. Suppose that a customer wants to use my sample website as a starting point, and they change the default namespace to OtherCompany.Whatever, this will obviously break my workaround. Is there a good solution to this problem? To summarize: I want to generate a service reference proxy in the original namespace, without referencing the assembly. Note: I have seen this question, but there was no solution provided that is acceptable for my use case. Edit: As John Saunders suggested, I've submitted some feedback to Microsoft about this: Feedback item @ Microsoft Connect

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  • jndi binding on jboss4.2.3 and ejb3

    - by broschb
    I am trying to deploy a stateless ejb on jboss 4.2.3 using ejb3 annotations. Everything builds and deploys correctly, and I do not get any errors when jboss starts up. However the ejb is not getting bound to any JNDI location for lookup when I look at the bindings in jboss. Below is what I have for my ejb. Remote @Remote public interface TestWebService { public String TestWebMethod(String param1, String param2); } Stateless EJB @Stateless @RemoteBinding(jndiBinding="TestWeb") @Remote(TestWebService.class) public class TestWebServiceBean implements TestWebService{ public String TestWebMethod(String param1, String param2) { System.out.println("HELLO "+param1+" "+param2); return "Welcome!!"; } } I have tried not having the @Remote and @RemoteBinding and it doesn't make a difference. I have also added and ejb-jar.xml file (which should not be needed with ejb3) and that does not appear to make a difference. Below is the output I see in the jboss log on startup. installing MBean: jboss.j2ee:ear=ejb_web_service_ear-0.0.1- SNAPSHOT.ear,jar=ejb_web_service-0.0.1-SNAPSHOT.jar,name=TestWebServiceBean,service=EJB3 with dependencies: 21:56:00,633 INFO [EJBContainer] STARTED EJB: com.tomax.ejb.TestWebServiceBean ejbName: TestWebServiceBean

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  • Extended SurfaceView onDraw never called

    - by Gab Royer
    Hi, I'm trying to modify the SurfaceView I use for doing a camera preview in order to display an overlaying square. However, the onDraw method of the extended SurfaceView is never called. Here is the source : public class CameraPreviewView extends SurfaceView { protected final Paint rectanglePaint = new Paint(); public CameraPreviewView(Context context, AttributeSet attrs) { super(context, attrs); rectanglePaint.setARGB(255, 200, 0, 0); rectanglePaint.setStyle(Paint.Style.FILL); rectanglePaint.setStrokeWidth(2); } @Override protected void onDraw(Canvas canvas){ canvas.drawRect(new Rect(10,10,200,200), rectanglePaint); Log.w(this.getClass().getName(), "On Draw Called"); } } public class CameraPreview extends Activity implements SurfaceHolder.Callback{ private SurfaceHolder holder; private Camera camera; @Override protected void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); // We remove the status bar, title bar and make the application fullscreen requestWindowFeature(Window.FEATURE_NO_TITLE); getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); // We set the content view to be the layout we made setContentView(R.layout.camera_preview); // We register the activity to handle the callbacks of the SurfaceView CameraPreviewView surfaceView = (CameraPreviewView) findViewById(R.id.camera_surface); holder = surfaceView.getHolder(); holder.addCallback(this); holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); } public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { Camera.Parameters params = camera.getParameters(); params.setPreviewSize(width, height); camera.setParameters(params); try { camera.setPreviewDisplay(holder); } catch (IOException e) { e.printStackTrace(); } camera.startPreview(); } public void surfaceCreated(SurfaceHolder holder) { camera = Camera.open(); } public void surfaceDestroyed(SurfaceHolder holder) { camera.stopPreview(); camera.release(); } }

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  • ASP.NET ListView, custom DataSources, and editing items

    - by Andrew Shepherd
    The MSDN walkthroughs provide a number of examples where you can drag a DataSource from the toolbox, run through some simple configuration steps, then drag a ListView onto the screen, point it at the DataSource, and hey - you've got full table editing. Now I'm trying to write my own DataSource class (a class that implements System.Web.UI.IDataSource) and my own DataSourceView class. I now assign an instance of this custom DataSource class to the ListView.DataSource propery. The display of all the items is working well. However, updating, inserting and deleting just is not working. I'm overriding every function I can in my DataSourceView class, and they just aren't being called. This is such a huge topic, I'll focus this question on one simple example: When you press the "Edit" button (the button inside the ItemTemplate with a CommandName of "Edit", you expect the ItemTemplate to be replaced by an EditItemTemplate. This did not happen. The only way I could get it to happen was to handle the onitemediting event. protected void _listViewPublicHolidays_ItemEditing(object sender, ListViewEditEventArgs e) { _listViewPublicHolidays.EditIndex = e.NewEditIndex; _listViewPublicHolidays.DataBind(); } This is hardly a problem, but how come I had to do it at all? In the MSDN walkthroughs where I attach a ListView to a LinqDataSource, this code doesn't have to be written. Can someone who's been here before hazard a guess as to what would be different or missing in my custom datasource?

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  • Question about decorator pattern and the abstract decorator class?

    - by es11
    This question was asked already here, but rather than answering the specific question, descriptions of how the decorator pattern works were given instead. I'd like to ask it again because the answer is not immediately evident to me just by reading how the decorator pattern works (I've read the wikipedia article and the section in the book Head First Design Patterns). Basically, I want to know why an abstract decorator class must be created which implements (or extends) some interface (or abstract class). Why can't all the new "decorated classes" simply implement (or extend) the base abstract object themselves (instead of extending the abstract decorator class)? To make this more concrete I'll use the example from the design patterns book dealing with coffee beverages: There is an abstract component class called Beverage Simple beverage types such as HouseBlend simply extend Beverage To decorate beverage, an abstract CondimentDecorator class is created which extends Beverage and has an instance of Beverage Say we want to add a "milk" condiment, a class Milk is created which extends CondimentDecorator I'd like to understand why we needed the CondimentDecorator class and why the class Milk couldn't have simply extended the Beverage class itself and been passed an instance of Beverage in its constructor. Hopefully this is clear...if not I'd simply like to know why is the abstract decorator class necessary for this pattern? Thanks. Edit: I tried to implement this, omitting the abstract decorator class, and it seems to still work. Is this abstract class present in all descriptions of this pattern simply because it provides a standard interface for all of the new decorated classes?

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  • Anyone know exactly which JMS messages will be redelivered in CLIENT_ACKNOWLEDGE mode if the client

    - by user360612
    The spec says "Acknowledging a consumed message automatically acknowledges the receipt of all messages that have been delivered by its session" - but what I need to know is what it means by 'delivered'. For example, if I call consumer.receive() 6 times, and then call .acknowledge on the 3rd message - is it (a) just the first 3 messages that are ack'd, or (b) all 6? I'm really hoping it's option a, i.e. messages after the one you called acknowledge on WILL be redelivered, otherwise it's hard to see how you could prevent message lost in the event of my receiver process crashing before I've had a chance to persist and acknowledge the messages. But the spec is worded such that it's not clear. I get the impression the authors of the JMS spec considered broker failure, but didn't spend too long thinking about how to protect against client failure :o( Anyway, I've been able to test with SonicMQ and found that it implements (a), i.e. messages 'received' later than the message you call .ack on DO get redelivered in the event of a crash, but I'd love to know how other people read the standard, and if anyone knows how any other providers have implemented CLIENT_ACKNOWLEDGE? (i.e. what the 'de facto' standard is) Thanks Ben

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  • Comparison operators not supported for type IList when Paging data in Linq to Sql

    - by Dan
    I can understand what the error is saying - it can't compare a list. Not a problem, other than the fact that I don't know how to not have it compare a list when I want to page through a model with a list as a property. My Model: Event : IEvent int Id string Title // Other stuff.. LazyList<EventDate> Dates // The "problem" property Method which pages the data (truncated): public JsonResult JsonEventList(int skip, int take) { var query = _eventService.GetEvents(); // Do some filtering, then page data.. query = query.Skip(skip).Take(take); return Json(query.ToArray()); } As I said, the above is truncated quite a bit, leaving only the main point of the function: filter, page and return JSON'd data. The exception occurs when I enumerate (.ToArray()). The Event object is really only used to list the common objects of all the event types (Meetings, Birthdays, etc - for example). It still implements IEvent like the other types, so I can't just remove the LazyList<EventDate> Dates' property unless I no longer implementIEvent` Anyway, is there a way to avoid this? I don't really want to compare a LazyList when I page, but I do not know how to resolve this issue. Thank you in advance! :)

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  • java.io.StreamCorruptedException: invalid stream header: 7371007E

    - by Alex
    Hello, this is pprobably a simple question . I got a client Server application which communicate using objects. when I send only one object from the client to server all works well. when I attempt to send several objects one after another on the same stream I get StreamCorruptedException. can some one direct me to the cause of this error . Thanks client write method private SecMessage[] send(SecMessage[] msgs) { SecMessage result[]=new SecMessage[msgs.length]; Socket s=null; ObjectOutputStream objOut =null; ObjectInputStream objIn=null; try { s=new Socket("localhost",12345); objOut=new ObjectOutputStream( s.getOutputStream()); for (SecMessage msg : msgs) { objOut.writeObject(msg); } objOut.flush(); objIn=new ObjectInputStream(s.getInputStream()); for (int i=0;i<result.length;i++) result[i]=(SecMessage)objIn.readObject(); } catch(java.io.IOException e) { alert(IO_ERROR_MSG+"\n"+e.getMessage()); } catch (ClassNotFoundException e) { alert(INTERNAL_ERROR+"\n"+e.getMessage()); } finally { try {objIn.close();} catch (IOException e) {} try {objOut.close();} catch (IOException e) {} } return result; } server read method //in is an inputStream Defined in the server SecMessage rcvdMsgObj; rcvdMsgObj=(SecMessage)new ObjectInputStream(in).readObject(); return rcvdMsgObj; and the SecMessage Class is public class SecMessage implements java.io.Serializable { private static final long serialVersionUID = 3940341617988134707L; private String cmd; //... nothing interesting here , just a bunch of fields , getter and setters }

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  • hadoop implementing a generic list writable

    - by Guruprasad Venkatesh
    I am working on building a map reduce pipeline of jobs(with one MR job's output feeding to another as input). The values being passed around are fairly complex, in that there are lists of different types and hash maps with values as lists. Hadoop api does not seem to have a ListWritable. Am trying to write a generic one, but it seems i can't instantiate a generic type in my readFields implementation, unless i pass in the class type itself: public class ListWritable<T extends Writable> implements Writable { private List<T> list; private Class<T> clazz; public ListWritable(Class<T> clazz) { this.clazz = clazz; list = new ArrayList<T>(); } @Override public void write(DataOutput out) throws IOException { out.writeInt(list.size()); for (T element : list) { element.write(out); } } @Override public void readFields(DataInput in) throws IOException{ int count = in.readInt(); this.list = new ArrayList<T>(); for (int i = 0; i < count; i++) { try { T obj = clazz.newInstance(); obj.readFields(in); list.add(obj); } catch (InstantiationException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } } } } But hadoop requires all writables to have a no argument constructor to read the values back. Has anybody tried to do the same and solved this problem? TIA.

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  • wcf class implementing multiple service contracts

    - by Archie
    Hello, I have a class TestService which implements two service contracts called IService1 and IService2. But I'm facing a difficulty in implementation. My Code looks as follows: Uri baseAddress = new Uri("http://localhost:8000/ServiceModel/Service"); Uri baseAddress1 = new Uri("http://localhost:8080/ServiceModel/Service1"); ServiceHost selfHost = new ServiceHost(typeof(TestService)); selfHost.AddServiceEndpoint(typeof(IService1), new WSHttpBinding(), baseAddress); selfHost.AddServiceEndpoint(typeof(IService2), new WSHttpBinding(), baseAddress1); ServiceMetadataBehavior smb = new ServiceMetadataBehavior(); smb.HttpGetEnabled = true; selfHost.Description.Behaviors.Add(smb); selfHost.Open(); Console.WriteLine("The service is ready."); Console.WriteLine("Press <ENTER> to terminate service."); Console.WriteLine(); Console.ReadLine(); selfHost.Close(); I'm getting a run time error as: The HttpGetEnabled property of ServiceMetadataBehavior is set to true and the HttpGetUrl property is a relative address, but there is no http base address. Either supply an http base address or set HttpGetUrl to an absolute address. What shall i do about it? Do I realy need two separate endpoints? Thanks.

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  • How to access a variable in other class?

    - by Christine
    Hi! I've problem regarding GUI with one Menu and one Order Class. I've created a variable to store how many items have been selected in the Menu Class. private int totalSelected; The var totalSelected is live updated. It can be changed anytime depending on actionPerformed() function.(Exp: totalSelected will add up all the selected items) In the Order Class, how can I access to the live update variable totalSelected in order to retrieve the live update value? When I invoke getTotalSelected() function inside the Menu Class, I will only obtain a 0 value. Thanks for your help ^^! Please allow me to specify my question clearer. public class MenuTab extends JPanel { private JLabel display; private int totalSelected; public MenuTab() { .... } } public getTotalSelected(){ return totalSelected; } private class SelectedListener implements ActionListener { public void actionPerformed() { ....... //Assume that totalSelected has been updated! display = new JLabel("Total: " + totalSelected); // OK to display totalSelected live value here. } } // A new class is the confirmation of order public class OrderConfirmedTab extends JPanel{ private JLabel displayTotal; private MenuTab order = new MenuTab(); public OrderConfirmedTab() { ...... int totalSelected = order.getTotalSelected(); displayTotal = new JLabel("Total: " + totalSelected); // Problem to display totalSelected live value here. // Will obtain 0; // How can I obtain the live updated value from class MenuTab? Thanks! } }

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  • MouseMotion Sensor Method Call

    - by user321894
    I have a soon-to-be due assignment due in computer science. I have encountered a problem, for which no matter how long I study the API's of the class and superclasses, I can not figure out. Suppose I wish to design a sort of "Breakout game" where the mouse motion controls the motion of a block that is used to bounce a ball, which then destroys multi colored bricks. How do you specifically make the block "listen" to the mouse? The below code is what I have attempted to achieve the desired results. /** Breakout Program*/ public class Breakout extends GraphicsProgram implements MouseMotionListener { ... /** The Paddle Itself */ private GRect paddle = new GRect(0, HEIGHT-PADDLEBOTTOM_OFFSET, PADDLEWIDTH, PADDLEHEIGHT); ... /** Run the Breakout program. */ public void run() { paddle.setFillColor(Color.BLACK); paddle.setFilled(true); add(paddle); paddle.addMouseListener(this); ... } /** Move the horizontal middle of the paddle to the x-coordinate of the mouse position - * -but keep the paddle completely on the board. */ public void mouseMoved(MouseEvent e) { GPoint p= new GPoint(e.getPoint()); double x = p.getX(); paddle.setLocation(x, HEIGHT-PADDLEBOTTOM_OFFSET); } } Any clarification on why/what I am doing incorrectly would be helpful, thanks.

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  • Android: How do I make a video splash screen repeat until webview finishes loading the url?

    - by Nikoli4
    I would like to make a small video (about 4 seconds) repeat until webview finishes loading the desired URL in the background. Right now the video plays once, then a blank black screen comes up until the page loads. I'm still pretty new to this... Thanks in advance for any help! Sorry for the EDITED stuff, but it was necessary. Here is my splash java import android.app.Activity; import android.content.Intent; import android.media.MediaPlayer; import android.media.MediaPlayer.OnCompletionListener; import android.os.Bundle; import android.widget.VideoView; public class Splash extends Activity implements OnCompletionListener { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.splash); VideoView video = (VideoView) findViewById(R.id.videoView); video.setVideoPath("android.resource://com.EDITED/raw/" + R.raw.splash); video.start(); video.setOnCompletionListener(this); } @Override public void onCompletion(MediaPlayer mp) { Intent intent = new Intent(this, EDITEDWebActivity.class); startActivity(intent); finish(); } }

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  • Weird camera Intent behavior

    - by David Erosa
    Hi all. I'm invoking the MediaStore.ACTION_IMAGE_CAPTURE intent with the MediaStore.EXTRA_OUTPUT extra so that it does save the image to that file. On the onActivityResult I can check that the image is being saved in the intended file, which is correct. The weird thing is that anyhow, the image is also saved in a file named something like "/sdcard/Pictures/Camera/1298041488657.jpg" (epoch time in which the image was taken). I've checked the Camera app source (froyo-release branch) and I'm almost sure that the code path is correct and wouldn't have to save the image, but I'm a noob and I'm not completly sure. AFAIK, the image saving process starts with this callback (comments are mine): private final class JpegPictureCallback implements PictureCallback { ... public void onPictureTaken(...){ ... // This is where the image is passed back to the invoking activity. mImageCapture.storeImage(jpegData, camera, mLocation); ... public void storeImage(final byte[] data, android.hardware.Camera camera, Location loc) { if (!mIsImageCaptureIntent) { // Am i an intent? int degree = storeImage(data, loc); // THIS SHOULD NOT BE CALLED WITHIN THE CAPTURE INTENT!! ....... // An finally: private int storeImage(byte[] data, Location loc) { try { long dateTaken = System.currentTimeMillis(); String title = createName(dateTaken); String filename = title + ".jpg"; // Eureka, timestamp filename! ... So, I'm receiving the correct data, but it's also being saved in the "storeImage(data, loc);" method call, which should not be called... It'd not be a problem if I could get the newly created filename from the intent result data, but I can't. When I found this out, I found about 20 image files from my tests that I didn't know were on my sdcard :) I'm getting this behavior both with my Nexus One with Froyo and my Huawei U8110 with Eclair. Could please anyone enlight me? Thanks a lot.

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  • Creating futures using Apple's GCD

    - by jer
    I'm working on a library which implements the actor model on top of Grand Central Dispatch (specifically the C level API libdispatch). Basically a brief overview of my system is as such: Communication happens between actors using messages Multicast communication only (one actor to many actors) Senders and receivers are decoupled from one another using a blackboard where messages are pushed to. Messages are sent in the default queue asynchronously using dispatch_group_async() once a message gets pushed onto the blackboard. I'm trying to implement futures in the language right now, so I've created a new type which holds some information: A group of its own The value being 'returned' However, I have a problem since dispatch_block_t is of type void (^)(void) so it doesn't return anything. So my idea of in my future_new() function of setting up another group which can be used to execute a block returning a result, which I can store in my "value" member in my future_t structure, isn't going to work. The rest of the futures implementation is very clear, except it all depends on being able to get the value into the future back from the actor, acting on the message. When using the library, it would greatly reduce its usefulness if I had to ask users (and myself) to be aware when futures were going to be used by other parts of the system—It just isn't practical. I'm wondering if anyone can think of a way around this?

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  • Hibernate MapKeyManyToMany gives composite key where none exists

    - by larsrc
    I have a Hibernate (3.3.1) mapping of a map using a three-way join table: @Entity public class SiteConfiguration extends ConfigurationSet { @ManyToMany @MapKeyManyToMany(joinColumns=@JoinColumn(name="SiteTypeInstallationId")) @JoinTable( name="SiteConfig_InstConfig", joinColumns = @JoinColumn(name="SiteConfigId"), inverseJoinColumns = @JoinColumn(name="InstallationConfigId") ) Map<SiteTypeInstallation, InstallationConfiguration> installationConfigurations = new HashMap<SiteTypeInstallation, InstallationConfiguration>(); ... } The underlying table (in Oracle 11g) is: Name Null Type ------------------------------ -------- ---------- SITECONFIGID NOT NULL NUMBER(19) SITETYPEINSTALLATIONID NOT NULL NUMBER(19) INSTALLATIONCONFIGID NOT NULL NUMBER(19) The key entity used to have a three-column primary key in the database, but is now redefined as: @Entity public class SiteTypeInstallation implements IdResolvable { @Id @GeneratedValue(generator="SiteTypeInstallationSeq", strategy= GenerationType.SEQUENCE) @SequenceGenerator(name = "SiteTypeInstallationSeq", sequenceName = "SEQ_SiteTypeInstallation", allocationSize = 1) long id; @ManyToOne @JoinColumn(name="SiteTypeId") SiteType siteType; @ManyToOne @JoinColumn(name="InstalationRoleId") InstallationRole role; @ManyToOne @JoinColumn(name="InstallationTypeId") InstType type; ... } The table for this has a primary key 'Id' and foreign key constraints+indexes for each of the other columns: Name Null Type ------------------------------ -------- ---------- SITETYPEID NOT NULL NUMBER(19) INSTALLATIONROLEID NOT NULL NUMBER(19) INSTALLATIONTYPEID NOT NULL NUMBER(19) ID NOT NULL NUMBER(19) For some reason, Hibernate thinks the key of the map is composite, even though it isn't, and gives me this error: org.hibernate.MappingException: Foreign key (FK1A241BE195C69C8:SiteConfig_InstConfig [SiteTypeInstallationId])) must have same number of columns as the referenced primary key (SiteTypeInstallation [SiteTypeId,InstallationRoleId]) If I remove the annotations on installationConfigurations and make it transient, the error disappears. I am very confused why it thinks SiteTypeInstallation has a composite key at all when @Id is clearly defining a simple key, and doubly confused why it picks exactly just those two columns. Any idea why this happens? Is it possible that JBoss (5.0 EAP) + Hibernate somehow remembers a mistaken idea of the primary key across server restarts and code redeployments? Thanks in advance, -Lars

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  • ASP.NET MVC - How to Unit Test boundaries in the Repository pattern?

    - by JK
    Given a basic repository interface: public interface IPersonRepository { void AddPerson(Person person); List<Person> GetAllPeople(); } With a basic implementation: public class PersonRepository: IPersonRepository { public void AddPerson(Person person) { ObjectContext.AddObject(person); } public List<Person> GetAllPeople() { return ObjectSet.AsQueryable().ToList(); } } How can you unit test this in a meaningful way? Since it crosses the boundary and physically updates and reads from the database, thats not a unit test, its an integration test. Or is it wrong to want to unit test this in the first place? Should I only have integration tests on the repository? I've been googling the subject and blogs often say to make a stub that implements the IRepository: public class PersonRepositoryTestStub: IPersonRepository { private List<Person> people = new List<Person>(); public void AddPerson(Person person) { people.Add(person); } public List<Person> GetAllPeople() { return people; } } But that doesnt unit test PersonRepository, it tests the implementation of PersonRepositoryTestStub (not very helpful).

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