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  • can't explain NullPointerException

    - by John Pope
    In the following code, i have a method to get a Vector of persons with the same zodiac sign. persoane is a Vector. I keep getting a NullPointerException at the if condition (persoane is definetly not null). I am unable to see why. Any help would be greatly appreciated public Vector<Persoana> cautaDupaZodie(String zodie) { Vector<Persoana> rezultat= new Vector<Persoana>(); for(int i=0; i<persoane.size(); i++) { if(persoane.get(i).getData().getZodie().equals(zodie)) //the exception occurs here { rezultat.add(persoane.get(i)); } } return rezultat; }

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  • Can I do a URL Rewrite to a different Tomcat instance?

    - by RodeoClown
    Is is possible to use Tuckey's URL Rewrite to rewrite to a different Tomcat instance? I have it working using crossContext="true" rewriting to a different servlet on the same tomcat instance, but our production server has multiple tomcat instances running and I want to rewrite to one of them instead? If it's not possible using the URL Rewrite filter, is there another way of doing it? Thanks.

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  • Using enums or a set of classes when I know I have a finite set of different options?

    - by devoured elysium
    Let's say I have defined the following class: public abstract class Event { public DateTime Time { get; protected set; } protected Event(DateTime time) { Time = time; } } What would you prefer between this: public class AsleepEvent : Event { public AsleepEvent(DateTime time) : base(time) { } } public class AwakeEvent : Event { public AwakeEvent(DateTime time) : base(time) { } } and this: public enum StateEventType { NowAwake, NowAsleep } public class StateEvent : Event { protected StateEventType stateType; public MealEvent(DateTime time, StateEventType stateType) : base(time) { stateType = stateType; } } and why? I am generally more inclined to the first option, but I can't explain why. Is it totally the same or are any advantages in using one instead of the other? Maybe with the first method its easier to add more "states", altough in this case I am 100% sure I will only want two states: now awake, and now asleep (they signal the moments when one awakes and one falls asleep).

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  • Best way to unit test Collection?

    - by limc
    I'm just wondering how folks unit test and assert that the "expected" collection is the same/similar as the "actual" collection (order is not important). To perform this assertion, I wrote my simple assert API:- public void assertCollection(Collection<?> expectedCollection, Collection<?> actualCollection) { assertNotNull(expectedCollection); assertNotNull(actualCollection); assertEquals(expectedCollection.size(), actualCollection.size()); assertTrue(expectedCollection.containsAll(actualCollection)); assertTrue(actualCollection.containsAll(expectedCollection)); } Well, it works. It's pretty simple if I'm asserting just bunch of Integers or Strings. It can also be pretty painful if I'm trying to assert a collection of Hibernate domains, say for example. The collection.containsAll(..) relies on the equals(..) to perform the check, but I always override the equals(..) in my Hibernate domains to check only the business keys (which is the best practice stated in the Hibernate website) and not all the fields of that domain. Sure, it makes sense to check just against the business keys, but there are times I really want to make sure all the fields are correct, not just the business keys (for example, new data entry record). So, in this case, I can't mess around with the domain.equals(..) and it almost seems like I need to implement some comparators for just unit testing purposes instead of relying on collection.containsAll(..). Are there some testing libraries I could leverage here? How do you test your collection? Thanks.

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  • Spring, Hibernate and Ehcache - Wrong entities

    - by asrijaal
    Hi there, I've got a webapp which uses spring+hibernate for my data layer. I'm using 2nd level caching with ehcache as provider. Everything seems to work so far but sometimes we encounter a problem which I can't really figure out atm. One of my tables is used for labels within the application - every user who logs access this table with his set language. Works for 90% of the time. But sometimes the user gets labels for the wrong language, e.g. instead of german everything turns to italian. After a logout and login all labels are correct. Does anyone of you encountered something like this? I'm not sure where to look at: spring+hibernate+ehcache is a solid package or is it not? Cheers

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  • What if I made an explicit reference to 'this' for use inside an inner class?

    - by badp
    So far, I've used this approach to access this from the scope of an inner class: class FooManagementWindow extends JFrame { JButton rejectFoo; //... void getFooAcceptingPanel(){ //... final FooManagementWindow referenceToThis = this; rejectFoo = new JButton("Reject"); rejectFoo.addEventListener(new EventListener() { @Override public void actionPerformed(ActionEvent arg) { referenceToThis.setEnabled(false); //this requires a network call //... referenceToThis.setEnabled(true); //the user may resume his work } }); //... } } However, I just learned that instead of declaring referenceToThis, a direct reference is kept for me as: FooManagementWindow.this I have no reason to think my less standard approach may lead to errors or weird corner cases. Or are there?

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  • Messaging strategies to connect different systems

    - by n002213f
    I have a system to handle Applications online and a different system to send SMS/Email notifications to applicants on completion using web services. I can't guarantee the availability of the SMS/Email gateway. Option 1 After an application is complete, place a message on a JMS queue. A Message Driven bean receives the message and make a call for the web service, if it fails leave the message on the queue. I suspect (please correct if incorrect) that if the gate way is offline the continuosly try to send the message which might use up valuable resources. Can the above option be refined are are there any other messaging strategies that can be used?

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  • MacPorts 1.8.2 fails to build db46 on Mac OS X 1.6.3

    - by themoch
    I'm trying to put a development environment on my Mac, and to do so I need to install several packages which require db46. When running sudo port install db46 I get the following error: ---> Computing dependencies for db46 ---> Fetching db46 ---> Attempting to fetch patch.4.6.21.1 from http://www.oracle.com/technology/products/berkeley-db/db/update/4.6.21/ ---> Attempting to fetch patch.4.6.21.2 from http://www.oracle.com/technology/products/berkeley-db/db/update/4.6.21/ ---> Attempting to fetch patch.4.6.21.3 from http://www.oracle.com/technology/products/berkeley-db/db/update/4.6.21/ ---> Attempting to fetch patch.4.6.21.4 from http://www.oracle.com/technology/products/berkeley-db/db/update/4.6.21/ ---> Attempting to fetch db-4.6.21.tar.gz from http://distfiles.macports.org/db4/4.6.21_6 ---> Verifying checksum(s) for db46 ---> Extracting db46 ---> Applying patches to db46 ---> Configuring db46 ---> Building db46 Error: Target org.macports.build returned: shell command " cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_ports_databases_db46/work/db-4.6.21/build_unix" && /usr/bin/make -j2 all " returned error 2 Command output: ../dist/../libdb_java/db_java_wrap.c:9464: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9487: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jlong' ../dist/../libdb_java/db_java_wrap.c:9509: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9532: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jlong' ../dist/../libdb_java/db_java_wrap.c:9563: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jint' ../dist/../libdb_java/db_java_wrap.c:9588: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jlong' ../dist/../libdb_java/db_java_wrap.c:9613: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jint' ../dist/../libdb_java/db_java_wrap.c:9638: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9666: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jlong' ../dist/../libdb_java/db_java_wrap.c:9691: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jlong' ../dist/../libdb_java/db_java_wrap.c:9716: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9739: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9771: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9796: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9819: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9842: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9867: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jobject' ../dist/../libdb_java/db_java_wrap.c:9899: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9920: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9943: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:9966: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jstring' ../dist/../libdb_java/db_java_wrap.c:9991: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'jint' ../dist/../libdb_java/db_java_wrap.c:10010: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:10046: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' ../dist/../libdb_java/db_java_wrap.c:10071: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'void' make: *** [db_java_wrap.lo] Error 1 make: *** Waiting for unfinished jobs.... Note: Some input files use unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details. cd ./classes && jar cf ../db.jar ./com/sleepycat Error: Status 1 encountered during processing. I have removed my /usr/local folder completely and it does not seem to help.

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  • How to access the private variables of a class in its subclass?

    - by giri
    This is a question I was asked in an interview: I have class A with private members and Class B extends A. I know private members of a class cannot be accessed, but the question is: I need to access private members of class A from class B, rather than create variables with the same value in class B. I hope I am clear with this question. Thanks.

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  • How to create updateable panel using AjaxLink of Wicket?

    - by Arne
    I try to realize a link (in fact many links) that update a table in an website using an AjaxLink of Wicket. But I fail, the table is never updated (I have "setOutputMarkupId(true)" and call "addComponent", but there must be something other thats wrong). How can I realize a panel with a number of links and a table that displays dynamic data, dependent on the link clicked? Can someone give an example (Maybe two links, when the first one is clicked the table displays two random numbers from 1-10, when the second is clicked the table displays random numbers from 1-100)? Without reloading the entire page, but only the html for the table?

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  • javax.persistence.NoResultException: getSingleResult() did not retrieve any entities

    - by apple1988
    Hello, i have created a namedquery with ejb to check if the username is used. When the singleResult is null, then i get the following Exception : javax.persistence.NoResultException: getSingleResult() did not retrieve any entities But this exception is the result that i want when the username is free. ^^ Here is the code: public User getUserByUsername(String username) throws DAOException{ try{ Query q = em.createNamedQuery(User.getUserByUsername); q.setParameter("username", username); return (User) q.getSingleResult(); }catch(Exception e){ throwException(username, e); return null; } } Does anybody know what the problem is. :( I will return null andy don`t get an Exception. Thank you very much

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  • Why is it not saying I won?

    - by Itachi
    This is my if statement... The buttons show up like this: This is my if statement if((buttons[3].getName()=="x" && buttons[6].getName()=="x" && buttons[9].getText()=="x")||(buttons[2].getName()=="x" && buttons[5].getName()=="x" && buttons[8].getName()=="x")|| ((buttons[1].getName()=="x") && (buttons[4].getName()=="x") && (buttons[7].getName()=="x"))){ JOptionPane.showMessageDialog(null,"X Wins"); } So if I select the 1st, 4th and 7th buttons (the left most 3 buttons) why does it not say "X Wins"? As a sidenote, yes the buttons should have the name "x"

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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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  • 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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  • 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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  • Jboss Seam Booking Example Extract Shared Libs From Ear

    - by michael lucas
    Example Booking Application, which JBoss Seam is shipped with, build into EAR file of about 7 MB. That's pretty much if you consider deploying this package to a remote Jboss server and possibly redeploying it package many times during your regular work. Lib files like richfaces and jsf-facelet make the lion's share of that EAR size. Why can't we just extract lib files into jboss-web.deployer directory on JBoss 4.2.0 GA server?

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  • Decorator Pattern - Multiple wrappers or quantity property?

    - by Jiminizer
    I'm making use of the decorator pattern for one of the first times, as part of a Uni project. As far as I can see, the pattern seems to be meant more for adding functionality in a modular manner, however we've been taught it with uses such as a coffee or pizza maker, where the object has modular components that are added - changing properties rather than behaviour. I'm trying to make the most of both uses, however I've come up with a question. In the example in the book we're using (Head First Design Patterns), the pattern is used in a coffee shop creating different coffees. So, for example, milk, froth, sugar, sprinkles are all decorators. How would you implement a system that used the same decorator multiple times (for example, a coffee with two sugars)? Would you rewrap the coffee, or give sugar a quantity property? Or (as i'm starting to suspect) would this never be an issue as the pattern isn't designed to be used this way?

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  • JFrame does not refresh after deleting an image

    - by dajackal
    Hi! I'm working for the first time with images in a JFrame, and I have some problems. I succeeded in putting an image on my JFrame, and now i want after 2 seconds to remove my image from the JFrame. But after 2 seconds, the image does not disappear, unless I resize the frame or i minimize and after that maximize the frame. Help me if you can. Thanks. Here is the code: File f = new File("2.jpg"); System.out.println("Picture " + f.getAbsolutePath()); BufferedImage image = ImageIO.read(f); MyBufferedImage img = new MyBufferedImage(image); img.resize(400, 300); img.setSize(400, 300); img.setLocation(50, 50); getContentPane().add(img); this.setSize(600, 400); this.setLocationRelativeTo(null); this.setVisible(true); Thread.sleep(2000); System.out.println("2 seconds over"); getContentPane().remove(img); Here is the MyBufferedImage class: public class MyBufferedImage extends JComponent{ private BufferedImage image; private int nPaint; private int avgTime; private long previousSecondsTime; public MyBufferedImage(BufferedImage b) { super(); this.image = b; this.nPaint = 0; this.avgTime = 0; this.previousSecondsTime = System.currentTimeMillis(); } @Override public void paintComponent(Graphics g) { Graphics2D g2D = (Graphics2D) g; g2D.setColor(Color.BLACK); g2D.fillRect(0, 0, this.getWidth(), this.getHeight()); long currentTimeA = System.currentTimeMillis(); //g2D.drawImage(this.image, 320, 0, 0, 240, 0, 0, 640, 480, null); g2D.drawImage(image, 0,0, null); long currentTimeB = System.currentTimeMillis(); this.avgTime += currentTimeB - currentTimeA; this.nPaint++; if (currentTimeB - this.previousSecondsTime > 1000) { System.out.format("Drawn FPS: %d\n", nPaint++); System.out.format("Average time of drawings in the last sec.: %.1f ms\n", (double) this.avgTime / this.nPaint++); this.previousSecondsTime = currentTimeB; this.avgTime = 0; this.nPaint = 0; } } }

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  • Does a HashSet make an internal copy of added Objects?

    - by praks5432
    Let's say I have a function that is recursive and is like this public void someRecur(List<Integer>someList){ if(someBreakCondition) Set.add(someList); for(int i = 0; i < someLen ; i++){ someList.add(someInt); someRecur(someList); someList.remove(someInt); } } Does the remove affect the list that has been put into the set? What should I do to give the set an actual copy of the list?

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  • In ArrayBlockingQueue, why copy into ReentrantLock field into local final variable?

    - by mjlee
    In ArrayBlockingQueue, any method that requires lock will get set 'final' local variable before calling 'lock()'. public boolean offer(E e) { if (e == null) throw new NullPointerException(); final ReentrantLock lock = this.lock; lock.lock(); try { if (count == items.length) return false; else { insert(e); return true; } } finally { lock.unlock(); } } Is there any reason to set a local variable 'lock' from 'this.lock' when field 'this.lock' is final also. Additionally, it also set local variable of E[] before acting on. private E extract() { final E[] items = this.items; E x = items[takeIndex]; items[takeIndex] = null; takeIndex = inc(takeIndex); --count; notFull.signal(); return x; } Is there any reason for copying to local final variable?

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  • How to use double buffering inside a thread and applet

    - by russell
    I have a question about when paint and update method is called?? i have game applet where i want to use double buffering.But i cant use it.the problem is In my game there is a ball which is moving inside run() method.I want to know how to use double buffering to swap the offscreen image and current image.Someone plz help. And when there is both update() and paint() method.which are called first,when and why ???

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  • How to lowercase every element of a collection efficiently?

    - by Chris
    Whats the most efficient way to lower case every element of a list or set? My idea for a List: final List<String> strings = new ArrayList<String>(); strings.add("HELLO"); strings.add("WORLD"); for(int i=0,l=strings.size();i<l;++i) { strings.add(strings.remove(0).toLowerCase()); } is there a better, faster way? How would this exmaple look like for a set? As there is currently no method for applying an operation to each element of a set (or list) can it be done without creating an additional temporary set? Something like this would be nice: Set<String> strings = new HashSet<String>(); strings.apply( function (element) { this.replace(element, element.toLowerCase();) } ); Thanks,

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