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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 context:annotation-config an alternative to @AutoWired?

    - by Antacid
    Is it correct that I can put context:annotation-config in my XML config and it will automatically inject the bean class without needing any annotations? So instead of using these annotation types: public class Mailman { private String name; @Autowired private Parcel Parcel; public Mailman(String name) { this.name = name; } @Autowired public void setParcel(Parcel Parcel) { this.Parcel = Parcel; } @Autowired public void directionsToParcel(Parcel Parcel) { this.Parcel = Parcel; } } I would just need to write this: <beans ... > <bean id="mailMan" class="MailMan"> <constructor-arg value="John Doe"/> </bean> <bean id="parcel" class="Parcel" /> <context:annotation-config /> </beans> and then my MailMan class would look a lot simpler without the need for annotations: public class Mailman { private String name; private Parcel Parcel; public Mailman(String name) { this.name = name; } }

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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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  • Problem on creating font using a custom ant task, which extends LWUIT's FontTask.

    - by Smithy
    Hi. I am new to LWUIT and j2me, and I am building a j2me application for showing Japanese text vertically. The phonetic symbol part of the text should be shown in relatively small font size (about half the size of the text), small Kanas need to be shown as normal ones, and some 'vertical only' characters need to be put into the Private Use Area, etc. I tried to build this font into a bitmap font using the FontTask ant task LWUIT provided, but found that it does support the customizations mentioned above. So I decided to write my own task and add those. Below is what I have achieved: 1 An ant task extending the LWUITTask task to support a new nested element <verticalfont>. public class VerticalFontBuildTask extends LWUITTask { public void addVerticalfont(VerticalFontTask anVerticalFont) { super.addFont(anVerticalFont); } } 2 The VerticalFontTask task, which extends the original FontTask. Instead of inserting a EditorFont object, it inserts a VerticalEditorFont object(derived from EditorFont) into the resource. public class VerticalFontTask extends FontTask { // some constants are omitted public VerticalFontTask() { StringBuilder sb = new StringBuilder(); sb.append(UPPER_ALPHABET); sb.append(UPPER_ALPHABET.toLowerCase()); sb.append(HALFWIDTH); sb.append(HIRAGANA); sb.append(HIRAGANA_SMALL); sb.append(KATAKANA); sb.append(KATAKANA_SMALL); sb.append(WIDE); this.setCharset(sb.toString()); } @Override public void addToResources(EditableResources e) { log("Putting rigged font into resource..."); super.addToResources(e); //antialias settings Object aa = this.isAntiAliasing() ? RenderingHints.VALUE_TEXT_ANTIALIAS_ON :RenderingHints.VALUE_TEXT_ANTIALIAS_OFF; VerticalEditorFont ft = new VerticalEditorFont( Font.createSystemFont( this.systemFace, this.systemStyle, this.systemSize), null, getLogicalName(), isCreateBitmap(), aa, getCharset()); e.setFont(getName(), ft); } VerticalEditorFont is just a bunch of methods logging to output and call the super. I am still trying to figure out how to extend it. But things are not going well: none of the methods on the VerticalEditorFont object get called when executing this task. My questions are: 1 where did I do wrong? 2 I want to embed a truetype font to support larger screens. I only need a small part of the font inside my application and I don't want it to carry a font resource weighing 1~2MB. Is there a way to extract only the characters needed and pack them into LWUIT?

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  • abstract class need acces to subclass atribute

    - by user1742980
    I have a problem with my code. public abstract class SimplePolygon implements Polygon { ... public String toString(){ String str = "Polygon: vertices ="; for(int i = 0;i<varray.length;i++){ str += " "; str += varray[i]; } return str; } } public class ArrayPolygon extends SimplePolygon { private Vertex2D[] varray; public ArrayPolygon(Vertex2D[] array){ varray = new Vertex2D[array.length]; if (array == null){} for(int i = 0;i<array.length;i++){ if (array[i] == null){} varray[i] = array[i]; } ... } Problem is, that i'm not allowed to add any atribute or method to abstract class SimplePolygon, so i'cant properly initialize varray. It could simply be solved with protected atrib in that class, but for some (stupid) reason i'cant do that. Has anybody an idea how to solve it without that? Thanks for all help.

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  • ExecutorSerrvice memory leak on exception

    - by TofuBeer
    I am having a hard time tracking this down since the profiler keeps crashing (hotspot error). Before I go too deep into figuring it out I'd like to know if I really have a problem or not :-) I have a few thread pools created via: Executors.newFixedThreadPool(10); The threads connect to different web sites and, on occasion, I get connection refused and wind up throwing an exception. When I later on call Future.get() to get the result it will then catch the ExecutionException that wraps the exception that was thrown when the connection could not be made. The program uses a fairly constant amount of memory up until the point in time that the exceptions get thrown (they tend to happen in batches when a particular site is overloaded). After that point the memory again remains constant but at a higher level. So my question is along the lines of is the memory behaviour (reported by "top" on Unix) expected because the exceptions just triggered something or do I probably have an actual leak that I'll need to track down? Additionally when Future.get() throws an exception is there anything else I need to do besides catch the exception (such as call Future.cancel() on it)?

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  • Log4j: Issues about the FallbackErrorHandler

    - by rdogpink
    I am working on a client-server-application and wanted to implement a flexible Loggingframework, so I chose log4j, which doesn´t really evolve anymore, but it is still handy framework. Because the Logging happens along the network, i wanted a solution for the case, that the network drive isn´t available, so the Logger has to change its destination file(s). Now I wanted to use the FallbackErrorHandler (configured with a XML-File) from the Log4j-library and the implementation worked: When my network drive isn´t available, it switches to a local Logfile, so no logging should be lost. But I headded two problems since yesterday and couldn´t figure or find out, how to solve it. No return to initial Logging Configuration: When the network drive is on again and the Logger could write to the old destinations, log4j still logs at the local drive and I can´t figure out, how to notify the original (primary) Logger to start again. I also tried to attach a second Appender to the ErrorHandler, which should mirror the failed primary Logger, that it tries to write on the network destination and when the network is on again, it logs in both files, on the local and on the network drive. But unfortunately it didn´t work out, I only got a failure message that the ErrorHandler-content doesn´t fit. log4j:WARN The content of element type "errorHandler" must match "(param*,root-ref?,logger-ref*,appender-ref?)". This is the responsible code. <appender name="TraceAppender" class="org.apache.log4j.DailyRollingFileAppender"> <!-- The second appender-ref "TestAppender" leads to the error. --> <errorHandler class="org.apache.log4j.varia.FallbackErrorHandler"> <logger-ref ref="com.idoh"/> <appender-ref ref="TraceFallbackAppender"/> <appender-ref ref="TestAppender"/> </errorHandler> <param name="datePattern" value=".yyyy-MM-dd" /> <param name="file" value="logs/Trace.txt" /> <layout class="org.apache.log4j.PatternLayout"> <param name="ConversionPattern" value="%-6r %d{HH:mm:ss,SSS} [%t] %-5p - %m%n"/> </layout> </appender> So, how could I trigger log4j to reset to initial configuration or hold a second appender parallel to the "Local-Logger". My Application should work by itself and shouldn´t have to be restarted often. First Error message is swallowed: I recognized, that the first message, which leads to the switching between the primary logger and the FallbackErrorHandler (for example a logging-request to a readonly-File), is swallowed, so neither the primary logger logs it (because it can´t) nor the backup-Logger knows what it missed. So anybody else ran in this problem and could solve it? Or has any suggestions?

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  • longest common subsequence

    - by davit-datuashvili
    i have following code public class LCS1 { public static String lcs(String a,String b) { String x; String y; int alen=a.length(); int blen=b.length(); if (alen==0 || blen==0) { return ""; } else if (a.charAt(alen-1)==b.charAt(blen-1)) { return lcs(a.substring(0,alen-1),b.substring(0,blen-1)); } else { x=lcs(a,b.substring(0,blen-1)); y=lcs(a.substring(0,alen-1),b); } return (x.length()>y.length()) ? x : y; } public static void main(String[]args){ String a="computer"; String b="houseboat"; System.out.println(lcs(a,b)); } } it should return "out" but returns nothing what is problem?

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  • Redeclaration of parameters

    - by Scott
    While looking through the Selenium source code I noticed the following in the PageFactory: public static <T> T initElements(WebDriver driver, Class<T> pageClassToProxy) { T page = instantiatePage(driver, pageClassToProxy); initElements(driver, page); return page; } public static void initElements(WebDriver driver, Object page) { final WebDriver driverRef = driver; initElements(new DefaultElementLocatorFactory(driverRef), page); } What is the benefit of having the following line? final WebDriver driverRef = driver; Wouldn't it have made sense to just make the parameter final, and then passing that along to the next method without declaring the new reference?

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  • Getting N random numbers that the sum is M

    - by marionmaiden
    Hello I want to get N random numbers that the sum of them is a value. For example, let's suppose I want 5 random numbers that their sum is 1 Then, a valid possibility is: 0.2 0.2 0.2 0.2 0.2 Other possibility is: 0.8 0.1 0.03 0.03 0.04 And so on. I need this for the creation of the matrix of belongings of the Fuzzy C-means.

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  • auto resize content of label

    - by user161004
    i have got a label in my program which displays a image. The problem id if an image is selected which is greater than the size of the label,only some part of the image is displayed while others are not displayed. What should i do so that the enire image is displayed???

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  • How to deploy a single webapp with multiple web-modules that may be removed or added individually

    - by Daniel Bleisteiner
    We currently run two separate webapps (WARs) deployed in one single EAR containing additional JARs and settings. To improve our deployment I want to split one of these webapps into different modules that may be build and packaged individually. But I've currently no clue on how to package these modules so that I'm able to add or remove them as desired - at best during runtime. The webapp is getting more and more complex and I'd like to separate some of the functionality into modules. These modules should be packaged as single archives. As long as they contain only classes and resources loaded through code I know how to do this (simple JARs). But how about JSPs? Normally a WAR file contains JSPs or HTML files. I my case it are JSF pages utilizing JBoss Seam and RichFaces. These modules will add classes, resources and JSF pages and other includes to the running webapplication. Is it somehow possible to deploy them as individual archives to serve the same running webapp? We are using Maven for our build and packaging and deploy into JBoss v4.

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  • Reflection in unit tests for checking code coverage

    - by Gary
    Here's the scenario. I have VO (Value Objects) or DTO objects that are just containers for data. When I take those and split them apart for saving into a DB that (for lots of reasons) doesn't map to the VO's elegantly, I want to test to see if each field is successfully being created in the database and successfully read back in to rebuild the VO. Is there a way I can test that my tests cover every field in the VO? I had an idea about using reflection to iterate through the fields of the VO's as part of the solution, but maybe you guys have solved the problem before? I want this test to fail when I add fields in the VO, and don't remember to add checks for it in my tests.

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  • How to unselect checkbox in chrome browser

    - by hudi
    in my wicket application I have 3 checkbox in form: add(new CheckBox("1").setOutputMarkupId(true)); add(new CheckBox("2").setOutputMarkupId(true)); add(new CheckBox("3").setOutputMarkupId(true)); form also contain behavior which unselect checboxes add(new AjaxEventBehavior("onclick") { private static final long serialVersionUID = 1L; @Override protected void onEvent(AjaxRequestTarget target) { List<Component> components = new ArrayList<Component>(); if (target.getLastFocusedElementId() != null) { if (target.getLastFocusedElementId().equals("1")) { components.add(get("2")); components.add(get("3")); } else if (target.getLastFocusedElementId().equals("2")) { components.add(get("1")); } else if (target.getLastFocusedElementId().equals("3")) { components.add(get("1")); } for (Component component : components) { component.setDefaultModelObject(null); target.add(component); } } } }); this works good on mozilla browser but in chrome this doesnt work. How I can improve to work this on chrome too ? UPDATE problem is in: target.getLastFocusedElementId() in mozilla this return what I want but in chrome it always return null but I dont know wh UPDATE 2 google chrome has bug in focus element: http://code.google.com/p/chromium/issues/detail?id=1383&can=1&q=window.focus%20type%3aBug&colspec=ID%20Stars%20Pri%20Area%20Type%20Status%20Summary%20Modified%20Owner so I need to do this in other way

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  • How to solve following issues?

    - by lakshmi
    hi im using postgresql database, I want to insert my datas into database,but whenever i run the server,it was display the following Error. Error:org.postgresql.util.PSQLException: FATAL: sorry, too many clients already How to solve this problem.My server.properties file is following. Sever.properties File: serverPortData=9042 serverPortCommand=9078 simocoConnectionURL=jdbc:postgresql://127.0.0.1:5432/vTrack?user=postgres&password=postgres dst=1 DatabaseName=vTrack ServerName=127.0.0.1 User=postgres Password=admin MaxConnections=90 InitialConnections=80 PoolSize=100 MaxPoolSize=100 KeepAliveTime=100 SimocoPoolSize=120 SimocoMaxPoolSize=120 SimocoKeepAliveTime=100 PortNumber=5432 Logging=1 Thanks.

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  • How the reading from and writing to sockets are synchronized?

    - by Roman
    We create a socket. On one side of the socket we have a "server" and on another side there is a "client". Both, the server and client, can write to and read from the socket. It is what i understand. I do not understand the following things: If a server reads from the socket, does it see in the socket only those stuff which was written to the socket by the client? I mean if server writes something to the socket and than reads from the socket, will it (server) see in the socket the stuff it (server) wrote there? I hope not. Let's consider the following situation. A client write something to the socket and then it writes something new to the socket and then server reads from the socket. What will the server see there? Only the "new" stuff written by the client or both "new" and "old" one? If a client (or server) writes to the socket, can it see if the written information was received by other side? For example out.println("Hello, Server!") will return true it server received this message.

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  • html:checkbox query

    - by sarah
    Hi All, i have the following code . and in Form is have property called isActive of type char ,how would i get the checked value of it ,i am getting some symbols like 'o' if checked. I am using userform.getIsActive() ,where i am going wrong .I want 'y' or 'n' values

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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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  • Ensuring all waiting threads complete

    - by Daniel
    I'm building a system where the progress of calling threads is dependent on the state of two variables. One variable is updated sporadically by an external source (separate from the client threads) and multiple client threads block on a condition of both variables. The system is something like this TypeB waitForB() { // Can be called by many threads. synchronized (B) { while (A <= B) { B.wait(); } A = B; return B; { } void updateB(TypeB newB) { // Called by one thread. synchronized (B) { B.update(newB); B.notifyAll(); // All blocked threads must receive new B. } } I need all the blocked threads to receive the new value of B once it has been updated. But the problem is once a single thread finishes and updates A, the waiting condition becomes true again so some of the other threads become blocked and don't receive the new value of B. Is there a way of ensuring that only the last thread that was blocked on B updates A, or another way of getting this behaviour?

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  • Ready to use TSP library

    - by Max
    Hi, I'm currently doing a project that requires some fast TSP solving (about 50-100 nodes in 2 seconds). There are a lots of approximation algorithms out there, but I don't have time nor will to analyze them and code them myself. Are there any free libraries that can solve TSP problem (approximation will do too)? Something like sortedNodes = solveTspPrettyPlease(nodes, 2sec) would be just great. Thanks in advance.

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