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  • Two collections manyToOne to same primary key

    - by Ethiel
    Hi, guys, I'm coding a web page in Hibernate-JPA and Oracle. I need the following: I have two classes: Place and Home. I need two collections of type Place in every Home: I do the following: Home: @ManyToOne @JoinColumn(name="ID_PLACES") private List<Places>places1; @ManyToOne @JoinColumn(name="ID_PLACES") private List<Places>Places2; However, hibernate got an exception (repeated column) and forces to me to mapping with insert and update to false. How Can I get Two ManyToOne relationship to same primary key with insert a true?.

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  • Transient variables are not captured properly on form submission

    - by Kalpana
    My User entity class have several member variables (e.g. String firstName) which are persisted and some transient variables (e.g. transient boolean selected) which are not. I have used the transient variable to capture a checkbox selection, but invariably the value never gets set and procesed properly until I set another bean value along with it. i.e. If User has firstName (mapped to a text field) and selected (mapped to a checkbox) If I just selected the value doesn't seem to be set on an update If I had selected the checkbox and the firstName field, the "selected" value is captured properly Can anyone tell me why this is happening?

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  • Generics in return types of static methods and inheritance

    - by Axel
    Generics in return types of static methods do not seem to get along well with inheritance. Please take a look at the following code: class ClassInfo<C> { public ClassInfo(Class<C> clazz) { this(clazz,null); } public ClassInfo(Class<C> clazz, ClassInfo<? super C> superClassInfo) { } } class A { public static ClassInfo<A> getClassInfo() { return new ClassInfo<A>(A.class); } } class B extends A { // Error: The return type is incompatible with A.getClassInfo() public static ClassInfo<B> getClassInfo() { return new ClassInfo<B>(B.class, A.getClassInfo()); } } I tried to circumvent this by changing the return type for A.getClassInfo(), and now the error pops up at another location: class ClassInfo<C> { public ClassInfo(Class<C> clazz) { this(clazz,null); } public ClassInfo(Class<C> clazz, ClassInfo<? super C> superClassInfo) { } } class A { public static ClassInfo<? extends A> getClassInfo() { return new ClassInfo<A>(A.class); } } class B extends A { public static ClassInfo<? extends B> getClassInfo() { // Error: The constructor ClassInfo<B>(Class<B>, ClassInfo<capture#1-of ? extends A>) is undefined return new ClassInfo<B>(B.class, A.getClassInfo()); } } What is the reason for this strict checking on static methods? And how can I get along? Changing the method name seems awkward.

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  • Hibernate is performing unwanted SELECTs on call to saveOrUpdate

    - by digiarnie
    Let's say I have a House entity which maps to many Person entities. I then load an existing House which has 20 occupants. beginTransaction(); House house = houseDao.find(1L); commitTransaction(); Later in the code, I can then add a new Person to the House: ... List<Person> people = house.getPeople(); people.add(new Person("Dilbert")); .... When I make the call: session.saveOrUpdate(house); Hibernate performs 21 queries: 1 to SELECT the House and 20 to SELECT each existing Person in the House. I'm sure it's a small issue on my part, however, what should I do so that I can add a new Person to the house without having such a heavy hit on the database in this situation? This is all done within the same session.

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  • playing two streams on android

    - by Yanush
    Hello, I'm looking for a way (or at least to be pointed in the right direction) to play two streams of audio on android simultaneously but each on a different channel (e.g one in the speaker and one through the headphones) I'm not even sure its possible hardware wise. Any thoughts, clues ? Y

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  • Projections.count() and Projections.countDistinct() both result in the same query

    - by Kim L
    EDIT: I've edited this post completely, so that the new description of my problem includes all the details and not only what I previously considered relevant. Maybe this new description will help to solve the problem I'm facing. I have two entity classes, Customer and CustomerGroup. The relation between customer and customer groups is ManyToMany. The customer groups are annotated in the following way in the Customer class. @Entity public class Customer { ... @ManyToMany(mappedBy = "customers", fetch = FetchType.LAZY) public Set<CustomerGroup> getCustomerGroups() { ... } ... public String getUuid() { return uuid; } ... } The customer reference in the customer groups class is annotated in the following way @Entity public class CustomerGroup { ... @ManyToMany public Set<Customer> getCustomers() { ... } ... public String getUuid() { return uuid; } ... } Note that both the CustomerGroup and Customer classes also have an UUID field. The UUID is a unique string (uniqueness is not forced in the datamodel, as you can see, it is handled as any other normal string). What I'm trying to do, is to fetch all customers which do not belong to any customer group OR the customer group is a "valid group". The validity of a customer group is defined with a list of valid UUIDs. I've created the following criteria query Criteria criteria = getSession().createCriteria(Customer.class); criteria.setProjection(Projections.countDistinct("uuid")); criteria = criteria.createCriteria("customerGroups", "groups", Criteria.LEFT_JOIN); List<String> uuids = getValidUUIDs(); Criterion criterion = Restrictions.isNull("groups.uuid"); if (uuids != null && uuids.size() > 0) { criterion = Restrictions.or(criterion, Restrictions.in( "groups.uuid", uuids)); } criteria.add(criterion); When executing the query, it will result in the following SQL query select count(*) as y0_ from Customer this_ left outer join CustomerGroup_Customer customergr3_ on this_.id=customergr3_.customers_id left outer join CustomerGroup groups1_ on customergr3_.customerGroups_id=groups1_.id where groups1_.uuid is null or groups1_.uuid in ( ?, ? ) The query is exactly what I wanted, but with one exception. Since a Customer can belong to multiple CustomerGroups, left joining the CustomerGroup will result in duplicated Customer objects. Hence the count(*) will give a false value, as it only counts how many results there are. I need to get the amount of unique customers and this I expected to achieve by using the Projections.countDistinct("uuid"); -projection. For some reason, as you can see, the projection will still result in a count(*) query instead of the expected count(distinct uuid). Replacing the projection countDistinct with just count("uuid") will result in the exactly same query. Am I doing something wrong or is this a bug? === "Problem" solved. Reason: PEBKAC (Problem Exists Between Keyboard And Chair). I had a branch in my code and didn't realize that the branch was executed. That branch used rowCount() instead of countDistinct().

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  • Hibernate Exception Fixed By Alt+Tab

    - by Lee Theobald
    Hi all, I've got a very curious problem in Hibernate that I would like some opinions on. In my code if I do the following: Go to page A Click a link on page A to be taken to page B Click on data item on page B Exception thrown I get an error telling me: failed to lazily initialize a collection of role: XYZ, no session or session was closed Fair enough. But when I do the same thing but add an alt+tab in the middle, everything is fine. E.g. Go to page A Click a link on page A to be taken to page B Hit ALt+Tab to switch to another application Hit ALt+Tab to switch back to the web browser Click on data item on page B Everything is fine. I'm a little confused as to how switching focus from my application makes it act as I want it to. Does anyone have any light to shine on the subject? I don't think it's a locking issue as even if I do the second set of steps quicker than the first, still no error. It's a Seam application using Hibernate 3.3.2.GA & 3.4.0.GA.

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  • Is there a way to wrap some local cache around a URLConnection

    - by Michael Neale
    I am using a URLConnection class - I want to be able to grab a stream to a given URL even if said URL is unavailable (ie cache the last known cope of the content on a URL, to some local file system dir) - now I have written this code a few times (never happy with it) and was wondering if there is something better out there that might be able to do this.

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  • Tomcat does not persist Session during restart

    - by mabuzer
    How to force Tomcat to serialize Session so that the user is kept logged in when Tomcat has restarted? Right now the user has to login again everytime. Added the following lines into web-app context.xml: <Manager className="org.apache.catalina.session.PersistentManager"> <Store className="org.apache.catalina.session.FileStore"/> </Manager> but still I see login page after Tomcat restart, I use Tomcat 6.0.24

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  • Implementing Unowned relationship Google App Engine

    - by nwallman
    My question is more of a best practices question on how to implement unowned relationships with Google App Engine. I am using JDO to do my persistence and like recommended in the google docs I'm persisting my list of unowned relationships like so: @PersistenceCapable(identityType = IdentityType.APPLICATION) public class User implements Serializable, UserDetails { ... @Persistent private List<Key> groups; ... } Now I came across my predicament when I went to query that list of objects using they Key object. So when I get my list of group keys in order to actually return a list of Group objects I have to do a look up on that key to get the object. My question is what is the recommended way of doing a unowned look up on a model object? Should I have an instance of the PersistanceManagerFactory on my Model object so I can do a lookup? Should I have an instance of my GroupDAO object on my Model object so I can do a look up? Should I have a Utility to do this type of lookup? I'm new to this so I just want to know which is the best way to do this. Thanks.

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  • Why baseclass calls method of subclass?

    - by twlkyao
    I encounter some code like the following: BaseClass: public class BaseClass { String name = "Base"; public BaseClass() { printName(); } public void printName() { System.out.println(name + "——Base"); } } DrivedClass: public class SubClass extends BaseClass { String name = "Sub"; public SubClass() { printName(); } public void printName() { System.out.println(name + "——Sub"); } public static void main(String[] args) { new SubClass(); } } When run the code, the output is: null——Sub Sub——Sub while it should be: Base——Base Sub——Sub I wonder why the BaseClass constructor calls the SubClass method, can anybody explain this? Thanks in advance.

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  • Whats wrong with this method?

    - by David
    Here's the method: public static String CPUcolor () { System.out.println ("What color am I?") ; String s = getIns() ; System.out.println ("are you sure I'm "+s+"? (Y/N)") ; String a = getIns() ; while (!((a.equals ("y")) || (a.equals ("Y")) || (a.equals ("n")) || (a.equals ("N")))) { System.out.println ("try again") ; a = getIns () ; } if (a.equals ("n") || a.equals("N")) {CPUcolor() ;} System.out.println ("I am "+s) ; return s ; } here is a possible output of this method (y's and n's are user inputs): What color am I? red are you sure I'm red? (Y/N) N What color am I? blue are you sure I'm blue? (Y/N) N What color am I? Yellow are you sure I'm Yellow? (Y/N) y I am Yellow I am blue I am red Why is it that the line's "I am blue" and "I am Blue" printed? Why are they printed in reverse order with red, the first entered, printed last?

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  • Oval collision detection not working properly

    - by William
    So I'm trying to implement a test where a oval can connect with a circle, but it's not working. edist = (float) Math.sqrt(Math.pow((px + ((pwidth/2) )) - (bx + (bsize/2)), 2) + Math.pow(-((py + ((pwidth/2)) ) - (bx + (bsize/2))), 2)); and here is the full code (requires Slick2D): import org.newdawn.slick.AppGameContainer; import org.newdawn.slick.BasicGame; import org.newdawn.slick.Color; import org.newdawn.slick.GameContainer; import org.newdawn.slick.Graphics; import org.newdawn.slick.Input; import org.newdawn.slick.SlickException; public class ColTest extends BasicGame{ float px = 50; float py = 50; float pheight = 50; float pwidth = 50; float bx = 200; float by = 200; float bsize = 200; float edist; float pspeed = 3; Input input; public ColTest() { super("ColTest"); } @Override public void init(GameContainer gc) throws SlickException { } @Override public void update(GameContainer gc, int delta) throws SlickException { input = gc.getInput(); try{ if(input.isKeyDown(Input.KEY_UP)) py-=pspeed; if(input.isKeyDown(Input.KEY_DOWN)) py+=pspeed; if(input.isKeyDown(Input.KEY_LEFT)) px-=pspeed; if(input.isKeyDown(Input.KEY_RIGHT)) px+=pspeed; } catch(Exception e){} } public void render(GameContainer gc, Graphics g) throws SlickException { g.setColor(new Color(255,255,255)); g.drawString("col: " + col(), 10, 10); g.drawString("edist: " + edist + " dist: " + dist, 10, 100); g.fillRect(px, py, pwidth, pheight); g.setColor(new Color(255,0,255)); g.fillOval(px, py, pwidth, pheight); g.setColor(new Color(255,255,255)); g.fillOval(200, 200, 200, 200); } public boolean col(){ edist = (float) Math.sqrt(Math.pow((px + ((pwidth/2) )) - (bx + (bsize/2)), 2) + Math.pow(-((py + ((pwidth/2)) ) - (bx + (bsize/2))), 2)); if(edist <= (bsize/2) + (px + (pwidth/2))) return true; else return false; } public float rotate(float x, float y, float ox, float oy, float a, boolean b) { float dst = (float) Math.sqrt(Math.pow(x-ox,2.0)+ Math.pow(y-oy,2.0)); float oa = (float) Math.atan2(y-oy,x-ox); if(b) return (float) Math.cos(oa + Math.toRadians(a))*dst+ox; else return (float) Math.sin(oa + Math.toRadians(a))*dst+oy; } public static void main(String[] args) throws SlickException { AppGameContainer app = new AppGameContainer( new ColTest() ); app.setShowFPS(false); app.setAlwaysRender(true); app.setTargetFrameRate(60); app.setDisplayMode(800, 600, false); app.start(); } }

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  • Twitter4J - Looking up profile details without logging in

    - by wvd
    Hello all, I've been using Twitter4J for a quite a while now, but I can't seem to find this particular feature. I want to be able to search on a name, and when the certain user is on twitter, I want to retrieve basic information such as tweets, followers (like you can access via http) - but how to do is in Twitter4J? Neither the code examples or the source could help me. Thanks, William van Doorn

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  • Sleep a thread until an event is attended in another thread from a different class

    - by Afro Genius
    I have an application that fires 2 threads, the 1st launches another class to do some processing which in turn launches a 3rd class to do yet more processing. The 2nd thread in the main class should wait until some event in the 3rd class completes before it performs its job. How can this be achieved? I had tried implementing a wait/notify to share a lock object between the two threads but technically this will not work as I found the hard way. Can I share a lock between classes? Note, an instance of the 3rd class is declared in the 1st class and passed as parameter to the 2nd class. Also I tried creating boolean value in 3rd class that tells when event is complete then poll 2nd thread till this value is true. This worked but is not very desirable. Also is actionListner a better approach to this problem?

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  • Hibernate: fetching multiple bags efficiently

    - by Jens Jansson
    Hi! I'm developing a multilingual application. For this reason many objects have in their name and description fields collections of something I call LocalizedStrings instead of plain strings. Every LocalizedString is basically a pair of a locale and a string localized to that locale. Let's take an example an entity, let's say a book -object. public class Book{ @OneToMany private List<LocalizedString> names; @OneToMany private List<LocalizedString> description; //and so on... } When a user asks for a list of books, it does a query to get all the books, fetches the name and description of every book in the locale the user has selected to run the app in, and displays it back to the user. This works but it is a major performance issue. For the moment hibernate makes one query to fetch all the books, and after that it goes through every single object and asks hibernate for the localized strings for that specific object, resulting in a "n+1 select problem". Fetching a list of 50 entities produces about 6000 rows of sql commands in my server log. I tried making the collections eager but that lead me to the "cannot simultaneously fetch multiple bags"-issue. Then I tried setting the fetch strategy on the collections to subselect, hoping that it would do one query for all books, and after that do one query that fetches all LocalizedStrings for all the books. Subselects didn't work in this case how i would have hoped and it basically just did exactly the same as my first case. I'm starting to run out of ideas on how to optimize this. So in short, what fetching strategy alternatives are there when you are fetching a collection and every element in that collection has one or multiple collections in itself, which has to be fetch simultaneously.

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  • Calling and consuming a JBoss Web Service from JavaScript (AJAX)

    - by Andreas Grech
    I am fiddling around with JBOSS's Web Services, and I have created the following: http://127.0.0.1:8080/IM/TestService?wsdl Now I need to access Web Methods from that Web Service from JavaScript. Say I have a web method named foo in TestService, how do I make an ajax call to it? I tried accessing the method via http://127.0.0.1:8080/IM/TestService/foo, but I'm getting an HTTP Status 404.

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