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  • How to hold a queue of messages and have a group of working threads without polling?

    - by Mark
    I have a workflow that I want to looks something like this: / Worker 1 \ =Request Channel= - [Holding Queue|||] - Worker 2 - =Response Channel= \ Worker 3 / That is: Requests come in and they enter a FIFO queue Identical workers then pick up tasks from the queue At any given time any worker may work only one task When a worker is free and the holding queue is non-empty the worker should immediately pick up another task When tasks are complete, a worker places the result on the Response Channel I know there are QueueChannels in Spring Integration, but these channels require polling (which seems suboptimal). In particular, if a worker can be busy, I'd like the worker to be busy. Also, I've considered avoiding the queue altogether and simply letting tasks round-robin to all workers, but it's preferable to have a single waiting line as some tasks may be accomplished faster than others. Furthermore, I'd like insight into how many jobs are remaining (which I can get from the queue) and the ability to cancel all or particular jobs. How can I implement this message queuing/work distribution pattern while avoiding a polling? Edit: It appears I'm looking for the Message Dispatcher pattern -- how can I implement this using Spring/Spring Integration?

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  • Is Catching a Null Pointer Exception a Code Smell?

    - by Drew
    Recently a co-worker of mine wrote in some code to catch a null pointer exception around an entire method, and return a single result. I pointed out how there could've been any number of reasons for the null pointer, so we changed it to a defensive check for the one result. However, catching NullPointerException just seemed wrong to me. In my mind, Null pointer exceptions are the result of bad code and not to be an expected exception in the system. Are there any cases where it makes sense to catch a null pointer exception?

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  • Where to get streaming (live) video and audio from camera example app for Android?

    - by Ole Jak
    Where to get streaming (live) video and audio from camera example for Android? Suppose I want to create some live video streaming service app so I'll have some cool server at the back end. And I know how to do that part. Suppose I have some stand alone app for PCs now I want to go on to mobile devices. So I want to see some sample app grabing audio and video streams from Phone, Synchronizing them, encoding somehow, and sending LIVE stream to server. I need any Open-Source sample that will do this or something like this. Where can I get one?

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  • Overriding a method in statically created objects

    - by I82Much
    All, Due to a bug in a library I'm using, I need to override the dispose() method on all objects extending a certain class and make it a NO-OP. I know that if I'm making new instances of the classes directly, this is easy to do: layerManager = new LayerManagerLayer(wwd) { @Override public void dispose() {} }; The problem is that a lot of the object instances I get are not directly constructed by my client code, but instead are created via static library method calls. // Here I want to override the dispose method, but I cannot. Layer l = ShapefileLoader.makeShapefileLayer(this.getClass().getResource("polylines10.shp")); Is there a way I can inject my dispose method into that statically created object without modifying the original sourcecode?

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  • Error in my web.xml

    - by Mercer
    Why i have an error in my web.xml when i want add servlet..? <servlet> <servlet-name>ClientServlet</servlet-name> <servlet-class>org.task.ClientServlet</servlet-class> <servlet-name>FactoryServlet</servlet-name> <servlet-class>org.task.FactoryServlet</servlet-class> <servlet-name>TraderServlet</servlet-name> <servlet-class>org.task.TraderServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>ClientServlet</servlet-name> <url-pattern>/ClientServlet</url-pattern> <servlet-name>FactoryServlet</servlet-name> <url-pattern>/FactoryServlet</url-pattern> <servlet-name>TraderServlet</servlet-name> <url-pattern>/TraderServlet</url-pattern> </servlet-mapping>

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  • Reflection: take values from an unknown running alpplication

    - by Dr.Lesh
    I'm writing an application that searchs for Semaphore types in the fields of unknown classes in unknown application (passed by user). I made it using Reflection and it worked. Now I want to fill up these semaphores with values, taking them from a running instance of this unknown application. So i took the class with "main" method of this unknown application, made a newInstance, and passed it when invoking the main method to start the application: Class mainClass = getItSomeWhere(); Object instance = mainClass.newInstance(); Method mainMethod = mainClass.getDeclaredMethod("main", new Class[]{String[].class}); mainMethod.invoke(instance, new Object[]{args}); and it worked fine. Now, how can I get the semaphore values, taking them from the classes of this running application, when I only have an instance of the main class? Many thanks for the answers.

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  • How to display panel which is of Singleton class in two different frames at a time?

    - by Sriku
    I am trying to display a singleton obj on two different Jframe, but it is displayed only in the Jframe in which the object is added at last ( in example Frame2). Other Jframe is empty. This Singleton class is inherited from Panel and contains a label in it. Can anybody please tell me how can i display this singleton object in two different frame ? public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { NewJFrame inst = new NewJFrame(); inst.setTitle("Frame1"); inst.setSize(300, 300); inst.setLocationRelativeTo(null); inst.setVisible(true); singltonpanel _sin = singltonpanel.instance(); inst.add(_sin); inst.repaint(); JFrame frame = new JFrame("Frame2"); frame.setSize(300, 300); frame.setVisible(true); singltonpanel _sin1 = singltonpanel.instance(); frame.add(_sin1); frame.repaint(); } });

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  • Problem inretrieving the name field in symbian using j2me

    - by learn
    I have added the firstname, middlename, lastname, suffix, prefix in symbian and now i want to retrieve each of this attributes of name. I am getting the firstname and lastname together by if(contactlist.isSupportedField(Contact.FORMATTED_NAME) && contact.countValues(Contact.FORMATTED_NAME)0) { mycontact.setName(contact.getString(Contact.FORMATTED_NAME, 0)); }

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  • Weather API to mobile platform

    - by Alex
    Hello everybody! I would like to ask from you guys/girls somebody used radar image api in MOBILE PLATFORM? I got some good provider but the user agreement don`t allow to use it in mobile platform. Even some good weather forecast API exists? (with moon phase,5-7 days forecast) and radar images ? Maybe search by US zip code?

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  • How to implement thread timeout in J2ME?

    - by lilo
    I am using Connector in J2ME and found that sometimes it take a very long time to send a request, and sometime it may halt the whole process. So I try to put code related to Connector in a thread and try to set timeout to the thread. But I found out that it's very difficult to do this in J2ME because there's no join(long) in J2ME. Is there any way to do this? Or any better way to deal with network connection in J2ME? Thanks a lot in advance.

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  • Tomcat startup logs - SEVERE: Error filterStart how to get a stack trace?

    - by Benju
    When I start Tomcat I get the following error: Jun 10, 2010 5:17:25 PM org.apache.catalina.core.StandardContext start SEVERE: Error filterStart Jun 10, 2010 5:17:25 PM org.apache.catalina.core.StandardContext start SEVERE: Context [/mywebapplication] startup failed due to previous errors It seems odd that the logs for Tomcat would not include a stack trace. Does somebody have a suggestion for how to increase the logging in Tomcat to get stack traces for errors like this?

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  • Determining if a coordinate is on a line

    - by TGCBraun
    I´m coding a little app that allows the user to draw multiple shapes and then remove or resize them. It´s working perfectly on rectangles and ovals, but I´m having issues with lines. Here´s a method that I wrote to find if the clicked spot on the screen is part of a specific line: public boolean containsLocation(int x, int y) { int m = (getY2() - getY()) / (getX2() - getX()); int b = getY() - (m * getX()); if (y == (m * x) + b) { return true; } return false; I´m using the famous y = mx + b formula and replacing y and x to find if the clicked spot is part of the line. The problem is when I click on the screen to remove the line, it only works if I click on the very fist coordinate (x,y) where the line starts. Nothing happens when I click anywhere else along the line. Can anyone shed a light on what I´m doing wrong? Thanks a lot.

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  • Error in creating alias in formula tag

    - by Senthilnathan
    Hi all I have a sql query in formula tag inside property tag. In that query i am creating alias name but the hibernate appends table name and throwing me error. select sum(e.salary) as sal from employee e but hibernate changes to select sum(e.salary) as employee.sal from employee e how to avoid this .... it should recognise as sal inside of employee.sal !!!

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  • Android Multithreading, creating new thread not executing rest of OnCreate

    - by Aidan
    Hi Guys, Basically I'm trying to run 2 threads within the same class at the same time. The code runs but only executes whats in run() and doesnt finish the onCreate method... anyone know why? public Camera1(){ t = new Thread(this, "My Thread"); t.start(); } public void run(){ bearing(); } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); new Camera1(); makeview(); tracking(); } Thanks!

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  • JTable - Getting a cell into Edit mode on pressing Tab

    - by Luhar
    This is possibly has a trivial solution, but I am at the end of my tether so I hope somebody can help out. I use a JTable which has a custom renderer and a custom editor for a set of columns. The renderer uses a JLabel component and the editor uses a JSpinner component. Our users want to be able to enter values in a column, and then press TAB or ENTER to move to the next editable cell in the table. If I understand correctly, this is the default behaviour for a JTable. However, this doesn't seem to work correctly for me. Until the user clicks on the cell, only the JLabel is displayed. The JSpinner (i.e. CellEditor) is only displayed when a user double clicks on the cell. So, it looks like the cell is going into "edit" mode only on MouseEvents, but not when it has focus. How do I get the cell to go into edit mode as soon as it has focus?

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  • How to read an xs:any response using CXF Generated Client?

    - by mfcabrera
    Hi, When consuming a webserice with CXF 2.1.4 (the generated client) I am having problem getting the response based on the following XSD snippet in the WSDL. CXF Generates a List representing it, but when I execute the service, the response comes null. I used wireshark to what I was reciving and indeed the response XMl is coming as expected, but CXF just give me null object. Below the XSD of the response object. And <!--- chunk --> <s:element name="GestionSIIFResponse"> <s:complexType> <s:sequence> <s:element minOccurs="0" maxOccurs="1" name="GestionSIIFResult"> <s:complexType mixed="true"> <s:sequence> <s:any /> </s:sequence> </s:complexType> </s:element> </s:sequence> </s:complexType> </s:element> <!--- chunk --> And this is the response I am getting from the service: <soap:Body> <GestionSIIFResponse xmlns="http://tempuri.org/"> <GestionSIIFResult> <Siif xmlns=""> <Pagina>NUY001B</Pagina> <Exitos> <ExitoRep> <CodExito>SIL0082</CodExito> <DesExito>La transaccion se ha aplicado satisfactoriamente</DesExito> </ExitoRep> </Exitos> <InformacionCab/> <Repeticiones/> </Siif> </GestionSIIFResult> </GestionSIIFResponse>

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  • How to get all n sets of three consecutives elements in an array or arraylist with a for statement ?

    - by newba
    Hi, I'm trying to do a convex hull approach and the little problem is that I need to get all sets of three consecutive vertices, like this: private void isConvexHull(Ponto[] points) { Arrays.sort(points); for (int i = 0; i <points.length; i++) { isClockWise(points[i],points[i+1],points[i+2]); } //... } I always do something that I don't consider clean code. Could please help me find one or more ways to this? I want it to be circular, i.e., if my fisrt point of the a set is the last element in the array, the 2nd element will be the 3rd in the list and the 3rd in that set will be the the 2nd element in the list, and so on. They must be consecutive, that's all.

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  • Please help me with Red5 server

    - by Nitesh Panchal
    hello, I have installed Red5 server successfully and also am able to run the demos fine. Now, I want to create a sample red5 server application. I created a sample project according to the specific directory structure that Red5 requires. But, now when i try to open this project in Netbeans 6.8, i am unable to because both have a different directory structure. So, Netbeans doesn't consider it as a project. I actually want to convert this project to a war file, so i can deploy it to red5/webapps directory and then red5 deployer service can make project out it automatically. How do i convert this project to a war file? because in Netbeans i am unable to open it. Please help. Thanks in advance :)

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  • Spring MVC 3.0 Rest problem

    - by Gidogeek
    Hi Guys, I'm trying out Spring MVC 3.0 for the first time and like to make it RESTfull. This is my controller: @Controller @RequestMapping(value = "/product") @SessionAttributes("product") public class ProductController { @Autowired private ProductService productService; public void setProductValidator(ProductValidator productValidator, ProductService productService) { this.productService = productService; } @RequestMapping(method = RequestMethod.GET) public Product create() { //model.addAttribute(new Product()); return new Product(); } @RequestMapping(method = RequestMethod.POST) public String create(@Valid Product product, BindingResult result) { if (result.hasErrors()) { return "product/create"; } productService.add(product); return "redirect:/product/show/" + product.getId(); } @RequestMapping(value = "/show/{id}", method = RequestMethod.GET) public Product show(@PathVariable int id) { Product product = productService.getProductWithID(id); if (product == null) { //throw new ResourceNotFoundException(id); } return product; } @RequestMapping(method = RequestMethod.GET) public List<Product> list() { return productService.getProducts(); } } I have 2 questions about this. I'm a believer in Convention over Configuration and therefor my views are in jsp/product/ folder and are called create.jsp , list.jsp and show.jsp this works relatively well until I add the @PathVariable attribute. When I hit root/product/show/1 I get the following error: ../jsp/product/show/1.jsp" not found how do I tell this method to use the show.jsp view ? If I don't add the RequestMapping on class level my show method will be mapped to root/show instead of root/owner/show how do I solve this ? I'd like to avoid using the class level RequestMapping.

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  • Blackberry app development - Drawing graphics on top of rendered text/buttons etc

    - by paullb
    Based off the one of the demos I have the following code. Currently what displays in the simulator is just hte contents of the paint function, however the ObjectChoiceField is still selectable if one happens to click in the right location. I would like both the text contents and the paint function contents to appear. Is this possible? public CityInfoScreen() { //invoke the MainScreen constructor super(); //add a screen title LabelField title = new LabelField("City Information Kiosk", LabelField.ELLIPSIS | LabelField.USE_ALL_WIDTH); setTitle(title); //add a text label add(new RichTextField("Major U.S. Cities")); //add a drop-down list with three choices: //Los Angeles, Chicago, or New York //... String choices[] = {"Los Angeles","Chicago","New York"}; choiceField = new ObjectChoiceField("select a city", choices); add(choiceField); Manager man = this.getMainManager(); } ... public void paint(Graphics g){ super.paint(g); // g.drawRect(0,left,500,500+left); g.setGlobalAlpha(0); g.drawRect(100-left,100-top,200,200); String text = new Integer(left).toString(); String text2 = new Integer(top).toString(); g.drawText(text + " " + text2,120-left,120-top); }

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  • Why baseclass calls method of subclass?

    - by twlkyao
    I encounter some code like the following: BaseClass: public class BaseClass { String name = "Base"; public BaseClass() { printName(); } public void printName() { System.out.println(name + "——Base"); } } DrivedClass: public class SubClass extends BaseClass { String name = "Sub"; public SubClass() { printName(); } public void printName() { System.out.println(name + "——Sub"); } public static void main(String[] args) { new SubClass(); } } When run the code, the output is: null——Sub Sub——Sub while it should be: Base——Base Sub——Sub I wonder why the BaseClass constructor calls the SubClass method, can anybody explain this? Thanks in advance.

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  • Using custom detectors with FindBugs Maven plugin

    - by Lóránt Pintér
    I have a nice JAR of some custom FindBugs detectors I'd like to use with the FindBugs Maven plugin. There is a way to do this with the plugin via the <pluginList> configuration parameter, but that only accepts local files, URLs, or resources. The only way I found for doing so is to somehow copy my JAR to a local file (maybe via the Dependency plugin) and then configure the FindBugs plugin something like this: <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>findbugs-maven-plugin</artifactId> <version>2.3.1</version> <configuration> <pluginList>${project.build.directory}/my-detectors.jar</pluginList> </configuration> </plugin> But this is not very flexible. Is there a way to use Maven's dependency management features together with FindBugs' plugins? I'd like to use something like this: <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>findbugs-maven-plugin</artifactId> <dependencies> <dependency> <groupId>com.lptr.findbugs</groupId> <artifactId>my-detectors</artifactId> <version>1.0</version> </dependency> </dependencies> </plugin> ...but this simply overrides the core FindBugs detectors.

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