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  • How to retrieve the ordered list of best articles having a minimum number of votes by using HSQL ?

    - by fabien7474
    I have a Vote domain class from my grails application containing properties like article_id and note I want to HQL query the Vote domain class in order to retrieve the 5 best rated articles having at least 10 votes. I tried : SELECT v.article_id, avg(v.note), count(*) FROM vote v where count(*) >= 10 group by v.article_id order by avg(v.note) desc limit 5; But unfortunately the insertion of where count(*) >= 10 throws an error. How can I do that in a simple way? Thank you for your help.

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  • Finding duplicates in a list using recursion?

    - by user1760892
    I'm suppose to find if there is duplicates in a list and return true or false using recursion only (no loops). So if ArrayList of char is used, [a,b,c,d,e] should return false. [a,a,b,c,d] or [a,b,b,c,c,d] should return true. I've tried and tested different ways and it worked for some cases but not all. I changed my code around and this is what I have now. (Has problem at the last if statement) Can anyone give me some hints? Thanks. public static <T> boolean duplicate(List<T> list) throws NullPointerException { return duplicateHelper(list, list.get(0)); } public static <T> boolean duplicateHelper(List<T> list, T t){ if (list == null) throw new NullPointerException(); if(list.isEmpty()) return false; if(list.size() > 1){ if(t.equals(list.get(1))) return true; } if(list.size() == 1) return false; if(!duplicateHelper(list.subList(1,list.size()), t)){ return duplicate(list.subList(1,list.size())); } return false; }

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  • Jsp declaration element

    - by Stardust
    <%! class father { static int s = 0; } %> <% father f1 = new father(); father f2 = new father(); f1.s++; out.println(f2.s); // It must print "1" %> When I run the file, I got this error. Can anybody explain? "The field s cannot be declared static; static fields can only be declared in static or top level types"

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  • calendar.getInstance() or calendar.clone()

    - by Pangea
    I need to make a copy of a given date 100s of times (I cannot pass-by-reference). I am wondering which of the below two are better options newTime=Calendar.getInstance().setTime(originalDate); OR newTime=originalDate.clone(); Performance is of main conern here. thx.

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  • Type mismatch: cannot convert from ArrayList<Data> to MyCollection

    - by Tommy
    I've read similar questions here but I'm still a little confused. MyCollection extends ArrayList<MyClass> MyClass implements Data yet this gives me the "cannot convert from ArrayList to MyCollection" MyCollection mycollection = somehandler.getCollection(); where getCollection looks like this public ArrayList<Data> getCollection() So my assumptions are obviously wrong. How can I make this work like I would like it to

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  • Which use cases make temporary JMS queues a better choice than persistent queues?

    - by Stephen Harmon
    When you are designing a JMS application, which use cases make you pick temporary queues over persistent queues? We use temporary queues for response messages. We're having some issues maintaining connections to the temp queues, though, so I am testing persistent response queues, instead. One clear disadvantage of persistent queues is that your application has to "know" about them beforehand. If that's not a big deal, though, are there use cases where temp queues are the obvious choice?

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  • Two pass JSP page rendering

    - by dotsid
    Suppose an example. I have following interface: public interface DataSource<T> { Future<T> fetch(); } This datasource can do asynchronous data fetching. And we have following tag for using datasource in JSP: <html> <d:fetch from="${orderDS}" var="orders"> <c:foreach in="${orders}" var="order"> <div class="order"> <c:out value="${order.title}" /> </div> </c:foreach> </d:fetch> </html> So, what I want? I want JSP rendering engine to call my custom tag (FetchTag in this example) twice. On first call FetchTag will do DataSource.fetch() call and save Future locally as a object field. On second call FetchTag do Future.get() call and will be blocked until data becomes available. Is there any way to do such a thing?

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  • Primary reasons why programming language runtimes use stacks?

    - by manuel aldana
    Many programming language runtime environments use stacks as their primary storage structure (e.g. see JVM bytecode to runtime example). Quickly recalling I see following advantages: Simple structure (pop/push), trivial to implement Most processors are anyway optimized for stack operations, so it is very fast Less problems with memory fragmentation, it is always about moving memory-pointer up and down for allocation and freeing complete blocks of memory by resetting the pointer to the last entry offset. Is the list complete or did I miss something? Are there programming language runtime environments which are not using stacks for storage at all?

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  • Anyone have a good solution for scraping the HTML source of a page with content (in this case, HTML

    - by phpwns
    Anyone have a good solution for scraping the HTML source of a page with content (in this case, HTML tables) generated with Javascript? An embarrassingly simple, though workable solution using Crowbar: <?php function get_html($url) // $url must be urlencode(d) { $context = stream_context_create(array( 'http' => array('timeout' => 120) // HTTP timeout in seconds )); $html = substr(file_get_contents('http://127.0.0.1:10000/?url=' . $url . '&delay=3000&view=browser', 0, $context), 730, -32); // substr removes HTML from the Crowbar web service, returning only the $url HTML return $html; } ?> The advantage to using Crowbar is that the tables will be rendered (and accessible) thanks to the headless mozilla-based browser. The problem, of course, is being dependent on on an external web service, especially given that SIMILE seems to undergo regular server maintenance. :( A pure php solution would be nice, but any functional (and reliable) alternatives would be great.

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  • Ref to map vs. map to refs vs. multiple refs

    - by mikera
    I'm working on a GUI application in Swing+Clojure that requires various mutable pieces of data (e.g. scroll position, user data, filename, selected tool options etc.). I can see at least three different ways of handling this set of data: Create a ref to a map of all the data: (def data (ref { :filename "filename.xml" :scroll [0 0] })) Create a map of refs to the individual data elements: (def datamap { :filename (ref "filename.xml") :scroll (ref [0 0]) })) Create a separate ref for each in the namespace: (def scroll (ref [0 0])) (def filename (ref "filename.xml")) Note: This data will be accessed concurrently, e.g. by background processing threads or the Swing event handling thread. However there probably isn't a need for consistent transactional updates of multiple elements. What would be your recommended approach and why?

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  • Exception durin processing XSLT transformation!

    - by Artic
    I'm usin such code to generate contents file. try { StreamResult result = new StreamResult(); TransformerFactory tf = TransformerFactory.newInstance(); for (String item: groups){ item = item.replaceAll(" ", "-").toLowerCase(); result.setOutputStream(new FileOutputStream(path+item+".html")); Templates templ = tf.newTemplates(xsltSource); Transformer transf = templ.newTransformer(); transf.clearParameters(); transf.setParameter("group", item); transf.transform(xmlSource, result); } } catch (TransformerConfigurationException e) { throw new SinkException(e.getMessage()); } catch (TransformerException e) { throw new SinkException(e.getMessage()); } But on second iteration I have an exception ERROR: javax.xml.transform.TransformerException: com.sun.org.apache.xml.internal.utils.WrappedRuntimeException: Read error Cann't understand what is the reason?

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  • inserted in multiple tables of database at a time

    - by rajkumari
    can we work with multiple tables of database with same connection object of database at same time . suppose i have inserted value in table 1 and at same time also inserted value in table 2 of data base with same object of data base connection. I am using sqlite database in code and getting database locked exception while commit() .

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  • stop thread that does not get interrupted

    - by prmatta
    I have a thread that sits and reads objects off of an ObjectInputStream: public void run() { try { ois = new ObjectInputStream(clientSocket.getInputStream()); Object o; while ((o = ois.readObject()) != null) { //do something with object } } catch (Exception ex) { //Log exception } } readObject does not throw InterruptedException and as far as I can tell, no exception is thrown when this thread is interrupted. How do I stop this thread?

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  • Where to put common setUp-code for differen testclasses?

    - by Benedikt
    I have several different test classes that require that certain objects are created before those tests can be run. Now I'm wondering if I should put the object initialization code into a separate helper class or superclass. Doing so would surely reduce the amount of duplicate code in my test classes but it would also make them less readable. Is there a guideline or pattern how to deal with common setUp-code for unit tests?

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  • Spring import runs hibernate persistence twice

    - by Jaanus
    I have 2 spring configurations : spring-servlet.xml spring-security.xml needed to add this line to security: <beans:import resource="spring-servlet.xml"/> Now hibernate is ran twice, this is log screenshot : my web.xml: <servlet> <servlet-name>spring</servlet-name> <servlet-class> org.springframework.web.servlet.DispatcherServlet </servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>spring</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> <listener> <listener-class> org.springframework.web.context.ContextLoaderListener </listener-class> </listener> <context-param> <param-name>contextConfigLocation</param-name> <param-value> /WEB-INF/spring-security.xml </param-value> </context-param>

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  • Compare Long values Struts2

    - by Marquinio
    Hi everyone I'm trying to compare two values using struts2 s:if tag but its not working. If I hardcode the values it works but I want it to be dynamic. The variable stringValue is of type String. The variable currentLongValue is of type Long. <s:set var="stringValue" value="order"/> <s:iterator value="listTest"> <s:set var="currentLongValue" value="value"/> <s:if test="#currentLongValue.toString() == #stringValue" > //Do something </s:if> <s:else> //Do something else </s:else> </s:iterator> For the s:if I have tried toString and also the equals(). It only works if I hardcode the values. Example: <s:if test="#currentLongValue == 1234"> Any clues? Thank you.

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  • Long running method causing race condition

    - by keeleyt83
    Hi, I'm relatively new with hibernate so please be gentle. I'm having an issue with a long running method (~2 min long) and changing the value of a status field on an object stored in the DB. The pseudo-code below should help explain my issue. public foo(thing) { if (thing.getStatus() == "ready") { thing.setStatus("finished"); doSomethingAndTakeALongTime(); } else { // Thing already has a status of finished. Send the user back a message. } } The pseudo-code shouldn't take much explanation. I want doSomethingAndTakeALongTime() to run, but only if it has a status of "ready". My issue arises whenever it takes 2 minutes for doSomethingAndTakeALongTime() to finish and the change to thing's status field doesn't get persisted to the database until it leaves foo(). So another user can put in a request during those 2 minutes and the if statement will evaluate to true. I've already tried updating the field and flushing the session manually, but it didn't seem to work. I'm not sure what to do from here and would appreciate any help. PS: My hibernate session is managed by spring.

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  • Fast response on first Socket I/O request but slow every other time when communicating with remote serial port

    - by GreenGodot
    I'm using sockets to pass Serial commands to a remote device. And the response to that request is sent back and printed out. However, I am having a problem in that the first time it is instant but the rest of the time it can take up to 20 seconds to receive a reply. I think the problem is with my attempt at threading but I am not entirely sure. new Thread() { @Override public void run() { System.out.println("opened"); try { isSocketRetrieving.setText("Opening Socket"); socket = new Socket(getAddress(), getRemotePort())); DataOutput = new DataOutputStream(socket .getOutputStream()); inFromServer = new BufferedReader( new InputStreamReader(socket .getInputStream())); String line = ""; isSocketRetrieving.setText("Reading Stream......"); while ((line = inFromServer.readLine()) != null) { System.out.println(line); if (line.contains(getHandshakeRequest())) { DataOutput.write((getHandshakeResponse()toString() + "\r").getBytes()); DataOutput.flush(); DataOutput .write((getCommand().toString() + "\r").getBytes()); DataOutput.flush(); int pause = (line.length()*8*1000)/getBaud(); sleep(pause); } else if (line.contains(readingObject .getExpected())) { System.out.println(line); textArea.append("value = " + line + "\n"); textAreaScroll.revalidate(); System.out.println("Got Value"); break; } } System.out.println("Ended"); try { inFromServer.close(); DataOutput.close(); socket.close(); isSocketRetrieving.setText("Socket is inactive..."); rs232Table.addMouseListener(listener); interrupt(); join(); } catch (IOException e) { e.printStackTrace(); } catch (InterruptedException e) { System.out.println("Thread exited"); } } catch (NumberFormatException e1) { e1.printStackTrace(); } catch (UnknownHostException e1) { e1.printStackTrace(); } catch (IOException e1) { e1.printStackTrace(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }.start();

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  • How to re-order a List<String>

    - by tarka
    I have created the following method: public List<String> listAll() { List worldCountriesByLocal = new ArrayList(); for (Locale locale : Locale.getAvailableLocales()) { final String isoCountry = locale.getDisplayCountry(); if (isoCountry.length() > 0) { worldCountriesByLocal.add(isoCountry); Collections.sort(worldCountriesByLocal); } } return worldCountriesByLocal; } Its pretty simple and it returns a list of world countries in the users locale. I then sort it to get it alphabetic. This all works perfectly (except I seem to occasionally get duplicates of countries!). Anyway, what I need is to place the US, and UK at the top of the list regardless. The problem I have is that I can't isolate the index or the string that will be returned for the US and UK because that is specific to the locale! Any ideas would be really appreciated.

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  • Spring Batch validation

    - by sergionni
    Hello. Does Spring Batch framework provide its specific validation mechanism? I mean, how it's possible to specify validation bean? My validation is result of @NamedQuery - if query returned result, the validation is OK, else - false.

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  • Where to handle fatal exceptions

    - by Stephen Swensen
    I am considering a design where all fatal exceptions will be handled using a custom UncaughtExceptionHandler in a Swing application. This will include unanticipated RuntimeExceptions but also custom exceptions which are thrown when critical resources are unavailable or otherwise fail (e.g. a settings file not found, or a server communication error). The UncaughtExceptionHandler will do different things depending on the specific custom exception (and one thing for all the unanticipated), but in all cases the application will show the user an error message and exit. The alternative would be to keep the UncaughtExceptionHandler for all unanticipated exceptions, but handle all other fatal scenarios close to their origin. Is the design I'm considering sound, or should I use the alternative?

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  • How to detect Out Of Memory condition?

    - by Jaromir Hamala
    I have an application running on Websphere Application Server 6.0 and it crashes nearly every day because of Out-Of-Memory. From verbose GC is certain there are the memory leaks(many of them) Unfortunately the application is provided by external vendor and getting things fixed is slow & painful process. As part of the process I need to gather the logs and heapdumps each time the OOM occurs. Now I'm looking for some way how to automate it. Fundamental problem is how to detect OOM condition. One way would be to create shell script which will periodically search for new heapdumps. This approach seems me a kinda dirty. Another approach might be to leverage the JMX somehow. But I have little or no experience in this area and don't have much idea how to do it. Or is in WAS some kind of trigger/hooks for this? Thank you very much for every advice!

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