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  • When should EntityManagerFactory instance be created/opened ?

    - by masato-san
    Ok, I read bunch of articles/examples how to write Entity Manager Factory in singleton. One of them easiest for me to understand a bit: http://javanotepad.blogspot.com/2007/05/jpa-entitymanagerfactory-in-web.html I learned that EntityManagerFactory (EMF) should only be created once preferably in application scope. And also make sure to close the EMF once it's used (?) So I wrote EMF helper class for business methods to use: public class EmProvider { private static final String DB_PU = "KogaAlphaPU"; public static final boolean DEBUG = true; private static final EmProvider singleton = new EmProvider(); private EntityManagerFactory emf; private EmProvider() {} public static EmProvider getInstance() { return singleton; } public EntityManagerFactory getEntityManagerFactory() { if(emf == null) { emf = Persistence.createEntityManagerFactory(DB_PU); } if(DEBUG) { System.out.println("factory created on: " + new Date()); } return emf; } public void closeEmf() { if(emf.isOpen() || emf != null) { emf.close(); } emf = null; if(DEBUG) { System.out.println("EMF closed at: " + new Date()); } } }//end class And my method using EmProvider: public String foo() { EntityManager em = null; List<Object[]> out = null; try { em = EmProvider.getInstance().getEntityManagerFactory().createEntityManager(); Query query = em.createNativeQuery(JPQL_JOIN); //just some random query out = query.getResultList(); } catch(Exception e) { //handle error.... } finally { if(em != null) { em.close(); //make sure to close EntityManager } } I made sure to close EntityManager (em) within method level as suggested. But when should EntityManagerFactory be closed then? And why EMF has to be singleton so bad??? I read about concurrency issues but as I am not experienced multi-thread-grammer, I can't really be clear on this idea.

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  • How to check if there is an active session in a JSF page?

    - by Roberto de Santis
    Hi, there is a way to check if there is an active session directly in jsf page? I have try this but it doesn't work: <p:ajaxStatus onerror="#{session == null ? 'idleDialog.show();' : null}" thank you in advance @Update I have see that onerror isn't fired even if viewExpiredException occurr. @Update 1 Ok i have implemented something that may work: <h:form> <p:idleMonitor timeout="10000" idleListener="#{idleMonitorController.idleListener}" onidle="sessionPoll.stop();idleDialog.show();"/> </h:form> <p:dialog header="Sessione scaduta per inattività" widgetVar="idleDialog" modal="true" width="400"> <h:outputText value="Sessione scaduta" /> <h:button value="Ripristina Sessione" onclick="idleDialog.hide();sessionPoll.start();" /> </p:dialog> <h:form prependId="false"> <p:poll widgetVar="sessionPoll" interval="1"/> </h:form> and this is the listner: public void idleListener(IdleEvent event) { System.out.println("aaaa"); final HttpServletRequest request = (HttpServletRequest) FacesContext.getCurrentInstance().getExternalContext().getRequest(); request.getSession(false).invalidate(); } now the only problem is that the session.invalidate doesn't work

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  • Is my Joda Time format pattern incorrect to produce a `T` and `Z` inside the parsed DateTime output?

    - by Tree
    Using Joda Time's pattern syntax below, this input string: Sunday, January 09, 2011 6:15:00 PM becomes this datetime: 2011-01-09T06:15:00.000Z Code: String start = "Sunday, January 09, 2011 6:15:00 PM"; DateTimeFormatter parser1 = DateTimeFormat.forPattern("EEEE, MMMM dd, yyyy H:mm:ss aa"); DateTime startTime = parser1.parseDateTime(start); Is this format pattern incorrect? If not, what are the T and Z doing inside the DateTime output? 2011-01-09T06:15:00.000Z

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  • How to use Scanner to accept only valid int as input

    - by John
    I'm trying to make a small program more robust and I need some help with that. Scanner kb = new Scanner(System.in); int num1; int num2 = 0; System.out.print("Enter number 1: "); num1 = kb.nextInt(); while(num2<num1) { System.out.print("Enter number 2: "); num2 = kb.nextInt(); } Number 2 has to be greater than number 1 Also I want the program to automatically check and ignore if the user enters a character instead of a number. Because right now when a user enters for example r instead of a number the program just exits.

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  • How to display a confirmation message in Tapestry5?

    - by shane87
    I am developing a website as part of my final year project and I want to display a message which confirms that an email has been sent. I know how to display custom error messages on a form i.e. You cannot go any further until the following errors are fixed : login name not known! I want to display a message which will say: your email has been sent! after I send an email. I have been told that I should display this message through the flash. I am unsure on how to do this, any help would be greatly appreciated.

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  • Why in the following code the output is different when I compile or run it more than once

    - by Sanjeev
    class Name implements Runnable { public void run() { for (int x = 1; x <= 3; x++) { System.out.println("Run by " + Thread.currentThread().getName() + ", x is " + x); } } } public class Threadtest { public static void main(String [] args) { // Make one Runnable Name nr = new Name(); Thread one = new Thread(nr); Thread two = new Thread(nr); Thread three = new Thread(nr); one.setName("A"); two.setName("B"); three.setName("C"); one.start(); two.start(); three.start(); } } The answer is different while compiling and running more then one time I don't know why? any idea.

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  • Find top N elements in a Multiset from Google Collections?

    - by dfrankow
    A Google Collections Multiset is a set of elements each of which has a count (i.e. may be present multiple times). I can't tell you how many times I want to do the following Make a histogram (exactly Multiset) Get the top N values from the histogram Examples: top 10 URLs, top 10 tags, ... What is the canonical way to do #2 given a Multiset? Here is a blog post about it, but that code is not quite what I want. First, it returns everything, not just top N. Second, it copies (is it possible to avoid a copy?). Third, I usually want a deterministic sort, i.e. tiebreak if counts are equal.

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  • Google Data Api returning an invalid access token

    - by kingdavies
    I'm trying to pull a list of contacts from a google account. But Google returns a 401. The url used for requesting an authorization code: String codeUrl = 'https://accounts.google.com/o/oauth2/auth' + '?' + 'client_id=' + EncodingUtil.urlEncode(CLIENT_ID, 'UTF-8') + '&redirect_uri=' + EncodingUtil.urlEncode(MY_URL, 'UTF-8') + '&scope=' + EncodingUtil.urlEncode('https://www.google.com/m8/feeds/', 'UTF-8') + '&access_type=' + 'offline' + '&response_type=' + EncodingUtil.urlEncode('code', 'UTF-8') + '&approval_prompt=' + EncodingUtil.urlEncode('force', 'UTF-8'); Exchanging the returned authorization code for an access token (and refresh token): String params = 'code=' + EncodingUtil.urlEncode(authCode, 'UTF-8') + '&client_id=' + EncodingUtil.urlEncode(CLIENT_ID, 'UTF-8') + '&client_secret=' + EncodingUtil.urlEncode(CLIENT_SECRET, 'UTF-8') + '&redirect_uri=' + EncodingUtil.urlEncode(MY_URL, 'UTF-8') + '&grant_type=' + EncodingUtil.urlEncode('authorization_code', 'UTF-8'); Http con = new Http(); Httprequest req = new Httprequest(); req.setEndpoint('https://accounts.google.com/o/oauth2/token'); req.setHeader('Content-Type', 'application/x-www-form-urlencoded'); req.setBody(params); req.setMethod('POST'); Httpresponse reply = con.send(req); Which returns a JSON array with what looks like a valid access token: { "access_token" : "{access_token}", "token_type" : "Bearer", "expires_in" : 3600, "refresh_token" : "{refresh_token}" } However when I try and use the access token (either in code or curl) Google returns a 401: curl -H "Authorization: Bearer {access_token}" https://www.google.com/m8/feeds/contacts/default/full/ Incidentally the same curl command but with an access token acquired via https://code.google.com/oauthplayground/ works. Which leads me to believe there is something wrong with the exchanging authorization code for access token request as the returned access token does not work. I should add this is all within the expires_in time frame so its not that the access_token has expired

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  • Android pattern for activity "flows"

    - by Otto
    I'm developing an android app that has a bunch of screens (activities) that are supposed to have "continue" and "back" buttons at the top. Can you tell me the right pattern for implementing this? I've seen some iPhone apps that have this but Android apps usually don't (I think partly because the back button is part of the phone). I found a post online about an Activity class that has "sub activities" which kind of seems like what I want to do, but I'm wondering if there's a simpler solution or pattern for creating flows like this (in which several activities are linked with continue/back buttons).

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  • Why does GC not clear the Dialog references?

    - by Pavel
    I have a dialog. Every time I create it and then dispose, it stays in memory. It seems to be a memory leak somewhere, but I can't figure it out. Do you have any ideas? See the screenshot of heap dump for more information. Thanks in advance. http://img441.imageshack.us/img441/5764/leak.png

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  • Problem processing large data using Applet-Servlet communication

    - by Marquinio
    Hi everyone. I have an Applet that makes a request to a Servlet. On the servlet it's using the PrintWriter to write the response back to Applet: out.println("Field1|Field2|Field3|Field4|Field5......|Field10"); There are about 15000 records, so the out.println() gets executed about 15000 times. Problem is that when the Applet gets the response from Servlet it takes about 15 minutes to process the records. I placed System.out.println's and processing is paused at around 5000, then after 15 minutes it continues processing and then its done. Has anyone faced a similar problem? The servlet takes about 2 seconds to execute. So seems that the browser/Applet is too slow to process the records. Any ideas appreciated. Thanks.

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  • Download Spring 2.5 sample applications

    - by Don
    Hi, I've seen various references to a couple of Spring MVC 2.5 example applications, named 'petclinic' and 'jpetstore'. I can't seem to find where to download these examples. Can anyone can provide a link to download them (ideally also with instructions for setup/deploying)? Thanks, Don

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  • I can't set main Class variable in onCreate Method

    - by natrollus
    Main class has two variables that want to reach another class: public class MyClassA extends Activity { int i = 1; Button b1; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); this.i = 31; this.b1 = (Button) findViewById(R.id.btn1); ~~ } } Second class want to call variables in mainClass object: public class MyclassB implements OnClickListener{ MyClassA mainClass = new MyClassA(); Button btn = mainClass.b1; int n = mainClass.i; public void OnClick(View arg0){ Log.v("btn:",btn); Log.v("int:",n); } //btn returns null; //int returns 1; But onCreate method not set variables.. Why not set main class variables like this.i=31 ?

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  • Is this a correct way to stop Execution Task

    - by Yan Cheng CHEOK
    I came across code to stop execution's task. private final ExecutorService executor = Executors.newSingleThreadExecutor(); public void stop() { executor.shutdownNow(); try { executor.awaitTermination(100, TimeUnit.DAYS); } catch (InterruptedException ex) { log.error(null, ex); } } public Runnable getRunnable() { return new Runnable() { public void run() { while (!Thread.currentThread().isInterrupted()) { // What if inside fun(), someone try to clear the interrupt flag? // Say, through Thread.interrupted(). We will stuck in this loop // forever. fun(); } } }; } I realize that, it is possible for Runnable to be in forever loop, as Unknown fun may Thread.sleep, clear the interrupt flag and ignore the InterruptedException Unknown fun may Thread.interrupted, clear the interrupt flag. I was wondering, is the following way correct way to fix the code? private final ExecutorService executor = Executors.newSingleThreadExecutor(); private volatile boolean flag = true; public void stop() { flag = false; executor.shutdownNow(); try { executor.awaitTermination(100, TimeUnit.DAYS); } catch (InterruptedException ex) { log.error(null, ex); } } public Runnable getRunnable() { return new Runnable() { public void run() { while (flag && !Thread.currentThread().isInterrupted()) { // What if inside fun(), someone try to clear the interrupt flag? // Say, through Thread.interrupted(). We will stuck in this loop // forever. fun(); } } }; }

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  • Blackberry development

    - by user348369
    hi i am working as a blackberry development we require to make a chat messenger. i am face some problem. our messenger list is not update automatically and our offline message come same like a one message mean require sepration.

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  • Would you take a paycut [closed]

    - by arinte
    I make 90K doing JEE5 (it is open I can use any tech I want which is nice) but don't like what I am doing to because it is too hw related. I have an offer for 88K and a bonus that would be 10% (almost assured) that I would guess would be paid in the 4th quarter. It is a j2ee, supposed to be moving to jee5 and there are no hw dependencies (banking type work). I think I would be interested, but I have always been told you do not take a pay cut and don't move laterally (go to another job at the same pay). I have been on other interviews but this is the only one that has panned out. Also with the current job there is 401k match, but with the new one there is 401k also and a pension. What would you do?

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  • Data Structures for hashMap, List and Set

    - by harigm
    Can any one please guide me to look in depth about the Data Structures used and how is it implemented in the List, Set and Maps of Util Collection page. In Interviews most of the questions will be on the Algorithms, but I never saw anywhere the implementation details, Can any one please share the information.

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  • Choosing design method for ladder-like word game.

    - by owca
    I'm trying to build a simple application, with the finished program looking like this : I will also have to implement two different GUI layouts for this. Now I'm trying to figure out the best method to perform this task. My professor told me to introduce Element class with 4 states : - empty - invisible (used in GridLayout) - first letter - other letter I've thought about following solutions (by List I mean any sort of Collection) : 1. Element is a single letter, and each line is Element[]. Game class will be array of arrays Element[]. I guess that's the dumbest way, and the validation might be troublesome. 2. Like previously but Line is a List of Element. Game is an array of Lines. 3. Like previously but Game is a List of Lines. Which one should I choose ? Or maybe do you have better ideas ? What collection would be best if to use one ?

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