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  • How to store some of the entity's values in another table using hibernate?

    - by nimcap
    Hi guys, is there a simple way to persist some of the fields in another class and table using hibernate. For example, I have a Person class with name, surname, email, address1, address2, city, country fields. I want my classes to be: public class Person { private String name; private String surname; private String email; private Address address; // .. } public class Address { private Person person; // to whom this belongs private String address1; private String address2; private String city; private Address country; // .. } and I want to store Address in another table. What is the best way to achieve this? Edit: I am using annotations. It does not have to be the way I described, I am looking for best practices. PS. If there is a way to make Address immutable (to use as a value object) that is even better, or maybe not because I thought everything from wrong perspective :)

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  • Extending an entity

    - by Kim L
    I have class named AbstractUser, which is annotated with @MappedSuperclass. Then I have a class named User (@Entity) which extends AbstractUser. Both of these exist in a package named foo.bar.framework. When I use these two classes, everything works just fine. But now I've imported a jar containing these files to another project. I'd like to reuse the User class and expand it with a few additional fields. I thought that @Entity public class User extends foo.bar.framework.User would do the trick, but I found out that this implementation of the User only inherits the fields from AbstractUser, but nothing from foo.bar.framework.User. The question is, how can I get my second User class to inherit all the fields from the first User entity class? Both User class implementation have different table names defined with @Table(name = "name").

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  • DataSource or ConnectionPoolDataSource for Application Server JDBC resources

    - by Vinnie
    When creating JNDI JDBC connection pools in an application server, I always specified the type as javax.sql.ConnectionPoolDataSource. I never really gave it too much thought as it always seemed natural to prefer pooled connections over non-pooled. However, in looking at some examples (specifically for Tomcat) I noticed that they specify javax.sql.DataSource. Further, it seems there are settings for maxIdle and maxWait giving the impression that these connections are pooled as well. Glassfish also allows these parameters regardless of the type of data source selected. Are javax.sql.DataSource pooled in an application server (or servlet container)? What (if any) advantages are there for choosing javax.sql.ConnectionPoolDataSource over javax.sql.DataSource (or vice versa)?

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  • Fastest way to put contents of Set<String> to a single String with words separated by a whitespace?

    - by Lars Andren
    I have a few Set<String>s and want to transform each of these into a single String where each element of the original Set is separated by a whitespace " ". A naive first approach is doing it like this Set<String> set_1; Set<String> set_2; StringBuilder builder = new StringBuilder(); for (String str : set_1) { builder.append(str).append(" "); } this.string_1 = builder.toString(); builder = new StringBuilder(); for (String str : set_2) { builder.append(str).append(" "); } this.string_2 = builder.toString(); Can anyone think of a faster, prettier or more efficient way to do this?

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  • Webapp: safetly update a shared List/Map in the AppContext

    - by al nik
    I've Lists and Maps in my WebAppContext. Most of the time these are only read by multiple Threads but sometimes there's the need to update or add some data. I'm wondering what's the best way to do this without incurring in a ConcurrentModificationException. I think that using CopyOnWriteArrayList I can achieve what I want in terms of - I do not have to sync on every read operation- I can safety update the list while other threads are reading it. Is this the best solution? What about Maps?

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  • Commercial Website architecture question

    - by Maxime ARNSTAMM
    Hello everyone, I have to write an architecture case study but there are some things that i don't know, so i'd like some pointers on the following : The website must handle 5k simultaneous users. The backend is composed by a commercial software, some webservices, some message queues, and a database. I want to recommend to use Spring for the backend, to deal with the different elements, and to expose some Rest services. I also want to recommend wicket for the front (not the point here). What i don't know is : must i install the front and the back on the same tomcat server or two different ? and i am tempted to put two servers for the front, with a load balancer (no need for session replication in this case). But if i have two front servers, must i have two back servers ? i don't want to create some kind of bottleneck. Based on what i read on this blog a really huge charge is handle by one tomcat only for the first website mentionned. But i cannot find any info on this, so i can't tell if it seems plausible. If you can enlight me, so i can go on in my case study, that would be really helpful. Thanks :)

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  • Getting a nicely formatted timestamp without lots of overhead?

    - by Brad Hein
    In my app I have a textView which contains real-time messages from my app, as things happen, messages get printed to this text box. Each message is time-stamped with HH:MM:SS. Up to now, I had also been chasing what seemed to be a memory leak, but as it turns out, it's just my time-stamp formatting method (see below), It apparently produces thousands of objects that later get gc'd. For 1-10 messages per second, I was seeing 500k-2MB of garbage collected every second by the GC while this method was in place. After removing it, no more garbage problem (its back to a nice interval of about 30 seconds, and only a few k of junk typically) So I'm looking for a new, more lightweight method for producing a HH:MM:SS timestamp string :) Old code: /** * Returns a string containing the current time stamp. * @return - a string. */ public static String currentTimeStamp() { String ret = ""; Date d = new Date(); SimpleDateFormat timeStampFormatter = new SimpleDateFormat("hh:mm:ss"); ret = timeStampFormatter.format(d); return ret; }

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  • OpenGL extensions available on different Android devices

    - by MH114
    I'm in the process of writing an OpenGL ES powered framework for my next Android game(s). Currently I'm supporting three different techniques of drawing sprites: the basic way: using vertex arrays (slow) using vertex-buffer-objects (VBOs) (faster) using the draw_texture extension (fastest, but only for basic sprites, i.e. no transforming) Vertex arrays are supported in OpenGL ES 1.0 and thus in every Android-device. I'm guessing most (if not all) of the current devices also support VBOs and draw_texture. Instead of guessing, I'd like to know the extensions supported by different devices. If majority of devices support VBOs, I could simplify my code and focus only on VBOs + draw_texture. It'd be helpful to know what different devices support, so if you have an Android-device, do report the extensions list please. :) String extensions = gl.glGetString(GL10.GL_EXTENSIONS); I've got a HTC Hero, so I can share those extensions next.

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  • I Want to get a week value

    - by satya
    I wan to get the value of only one week. I am using the following JPA query: SELECT a FROM questions.dao.hibernate.Questions a WHERE (a.posted_date-CURRENT_DATE)>= 7 But I am getting an error message like org.hibernate.QueryException: could not resolve property: posted_date of: questions.dao.hibernate.Questions [SELECT a FROM questions.dao.hibernate.Questions a WHERE (a.posted_date-CURRENT_DATE)>=7] Please help me. Thanks

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  • storage service with google app engine.

    - by Bunny Rabbit
    i've been assigned a project to create a filestorage service on google applet engine.but i am really doubtful wheather it's possible or not given the 30 sec limit to process the response and moreover its the bigtable is just a database system not a storage server .am i correct ?

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  • How can i use Stopwatch [ apache ] to calculate the time taken by a method?

    - by Rakesh Juyal
    I am using StopWatch [ apache ] to get the time taken by my method. The approach i am following is StopWatch stopWatch = new StopWatch(); stopWatch.start(); myMethod(); stopWatch.stop(); logger.info( "Time taken by myMethod: " + stopWatch.getTime() + " millisecs"); stopWatch.reset(); stopWatch.start(); anotherMethod(); stopWatch.stop(); logger.info( "Time taken by anotherMethod: " + stopWatch.getTime() + " millisecs"); Thats the only thing i know about StopWatch :). How/when to use split(), unsplit(), getSplitTime(),suspend()... ?

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  • Why won't this println command start a new line?

    - by David
    Here's the relevant code: public static void printBoarders (Territory x) { int t = 0 ; int n = 0 ; for (int i = 0; i<x.borders.length; i++) { if (x.borders[i] == -1) t = i ; } for (int j = 0; j<x.borders.length; j++) { if (x.borders[j] == 1) n++ ; } Territory.translate (t) ; System.out.print (" has " + n + " borders: ") ; Territory.translate (x.borders) ; System.out.println (" ") ; } When I run this, I get everything on one line without a line break. Why isn't the System.out.println (" ") ; creating a line break? Here is an example of what the output winds up being: Northwest Territory, Alberta, Kamchatka, hidavid-names-macbook-pro:~ davidname$ EDIT: the problem was that this method was never being invoked. A different one which i was replacing was. All is well.

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  • Why doesn't this loop terminate?

    - by David
    Here's the sample code: public static void col (int n) { if (n % 2 == 0) n = n/2 ; if (n % 2 != 0) n = ((n*3)+1) ; System.out.println (n) ; if (n != 1) col (n) ; } this works just fine until it gets down to 2. then it outputs 2 4 2 4 2 4 2 4 2 4 infinitely. it seems to me that if 2 is entered as n then (n % 2 == 0) is true 2 will be divided by 2 to yeild 1. then 1 will be printed and since (n != 1) is false the loop will terminate. Why doesn't this happen?

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  • Jetty RewriteHandler and RewriteRegexRule

    - by Justin
    I'm trying to rewrite a URL for a servlet. The URL gets rewritten correctly, but the context doesn't match after that. Any idea how to get this to work? RewriteHandler rewriteHandler = new RewriteHandler(); rewriteHandler.setRewriteRequestURI(true); rewriteHandler.setRewritePathInfo(true); rewriteHandler.setOriginalPathAttribute("requestedPath"); RewriteRegexRule rewriteRegexRule = new RewriteRegexRule(); rewriteRegexRule.setRegex("/r/([^/]*).*"); rewriteRegexRule.setReplacement("/r?z=$1"); rewriteHandler.addRule(rewriteRegexRule); ContextHandlerCollection contextHandlerCollection = new ContextHandlerCollection(); Context servletContext = new Context(contextHandlerCollection, "/"); servletContext.addServlet(new ServletHolder(new RedirectServlet()), "/r"); So basically /r/asdf gets rewritten to /r?z=asdf. However, the rewritten /r?z=asdf is now not processed by the servlet. Also, /r?z=asdf does work if called directly.

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  • How to reference another project in Eclipse with Google appengine project?

    - by virsir
    I am trying to extract some common classes out to be a common jar, and I want to reference it by the appengine project in Eclipse. It compiles well but could not run. The console just told that some classes from the common jar project could not be found. I know I can just export the project into a jar, but I may want to change it sometimes, so I prefer keep it dynamic. And I know maven may be an option but there is no official maven support for appengine, and I will not try to learn it. Then how can I make it work?

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  • Customizing error handling of JAXB unmarshall process

    - by ekeren
    Assuming I have a schema that describes a root element class Root that contains a List<Entry> where the Entry class has a required field name. Here is how it looks in code: @XmlRootElement class Root{ @XmlElement(name="entry") public List<Entry> entries = Lists.newArrayList(); } @XmlRootElement class Entry{ @XmlElement(name="name",required=true) public String name; } If I supply the following XML for unmarshalling: <root> <entry> <name>ekeren</name> </entry> <entry> </entry> </root> I have a problem because the second entry does not contain a name. So unmarshall produces null. Is there a way to customize JAXB to unmarshall a Root object that will only contain the "good" entry?

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  • How to add two label in one gridbox?

    - by Jessy
    Hello everyone, How can I add two label in the same grid box? e.g. in row 1, col 1 the will be 2 labels? The code below will add the label in two different grid. JPanel chckBox = new JPanel(new GridLayout(1,8,3,3)); JLabel label1 = new JLabel("A"); JLabel label2 = new JLabel("B"); ... chckBox.add(label1); chckBox.add(label2); ...

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  • What does this do and why does it require a transaction?

    - by S. Palin
    What does the following code example do and why does it require a transaction? // PersistenceManager pm = ...; Transaction tx = pm.currentTransaction(); User user = userService.currentUser(); List<Account> accounts = new ArrayList<Account>(); try { tx.begin(); Query query = pm.newQuery("select from Customer " + "where user == userParam " + "parameters User userParam"); List<Customer> customers = (List<Customer>) query.execute(user); query = pm.newQuery("select from Account " + "where parent-pk == keyParam " + "parameters Key keyParam"); for (Customer customer : customers) { accounts.addAll((List<Account>) query.execute(customer.key)); } } finally { if (tx.isActive()) { tx.rollback(); } }

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  • Recommendations for an in memory database vs thread safe data structures

    - by yx
    TLDR: What are the pros/cons of using an in-memory database vs locks and concurrent data structures? I am currently working on an application that has many (possibly remote) displays that collect live data from multiple data sources and renders them on screen in real time. One of the other developers have suggested the use of an in memory database instead of doing it the standard way our other systems behaves, which is to use concurrent hashmaps, queues, arrays, and other objects to store the graphical objects and handling them safely with locks if necessary. His argument is that the DB will lessen the need to worry about concurrency since it will handle read/write locks automatically, and also the DB will offer an easier way to structure the data into as many tables as we need instead of having create hashmaps of hashmaps of lists, etc and keeping track of it all. I do not have much DB experience myself so I am asking fellow SO users what experiences they have had and what are the pros & cons of inserting the DB into the system?

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  • Correct way to persist Quartz triggers

    - by davioooh
    I'm quite new to Quartz and now I need to schedule some jobs in Spring Web App. I know about Spring + Quartz integration (I'm using Spring v 3.1.1) but I'm wondering if it's the right way to follow. In particular I need to persist my scheduled tasks in a DB so I can re-initialize them when application is restarted. Are there some utilities provided by Spring scheduling wrapper to do this? Can you suggest me some "well known" approach to follow?

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  • How to refresh an activity? Map View refresh fails

    - by poeschlorn
    Hi Guys, after implementing some Android Apps, including several Map activities, I try to refresh the activity when the GPS listener's onLocationChanged() mehtod is called. I have no idea how to tell the map activity to refresh on its own and display the new coords... the coords to store will have to be in global values, so that the location listener will have access to it. In my sample GPS-class (see code below) I just changed the text of a text view....but how to do that in map view? private class MyLocationListener implements LocationListener { @Override public void onLocationChanged(Location loc) { final TextView tv = (TextView) findViewById(R.id.myTextView); if (loc != null) { tv.setText("Location changed : Lat: " + loc.getLatitude() + " Lng: " + loc.getLongitude()); } } I think the solution of this Problem won't be very difficult, but I just need the beginning ;-) This whole app shall work like a really simple navigation system. It would be great if someone could help me a little bit further :) nice greetings, Poeschlorn

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