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  • How to introduce multi-column constraint with JPA annotations?

    - by plouh
    I am trying to introduce a multi-key constraint on a JPA-mapped entity: public class InventoryItem { @Id private Long id; @Version private Long version; @ManyToOne @JoinColumn("productId") private Product product; @Column(nullable=false); private long serial; } Basically (product, serial) pair should be unique, but I only found a way to say that serial should be unique. This obviously isn't a good idea since different products might have same serial numbers. Is there a way to generate this constraint via JPA or am I forced to manually create it to DB?

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  • How to unload JVM from a living process?

    - by Guy
    Hi, I'm working with JNI and trying to unload (destroy) the VM using DestoryJavaVM function (I first call DetachCurrentThread method). It seems like the it has now influence on the VM and it is still up after the call. I read in old Sun posts that DestoryJavaVM had problems in the past (JDK1.1-1.3 in 2001) but I'm using JRE 6 and it probably should work now, right? I need to Load\Unload a VM in the same living process since each loading requires another classes to load. Any ideas how it can be done? Thanks, Guy

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  • Discard unprintable characters returned in server's XML response

    - by Penang
    While trying to use the Bing API to search, I am getting characters that are not printable and do not seem to hold any extra information. The goal is to save the XML (UTF-8) response as a text file to be parsed later. My code currently looks something like this: URL url = new URL(queryURL); BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream())); BufferedWriter out = new BufferedWriter(new FileWriter(query+"-"+saveResultAs)); String str = in.readLine(); out.write(str); in.close(); out.close(); When I send the contents of 'str' to console it looks something like this: and here's a what the newly created local XML file looks like: What should I be doing to convert the UTF-8 text so that str does not have the extra characters?

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  • Counting substring, while loop

    - by user1554786
    public class SubstringCount { public static void main(String[] args) { Scanner scan = new Scanner(System.in); System.out.println("Enter a word longer than 4 characters, and press q to quit"); int count = 0; while (scan.hasNextLine()) { System.out.println("Enter a word longer than 4 characters, and press q to quit"); String word = scan.next(); if (word.substring(0,4).equals("Stir")) { count++; System.out.println("Enter a word longer than 4 characters, and press q to quit"); scan.next(); } else if (word.equals("q")) { System.out.println("You have " + count + ("words with 'Stir' in them")); } else if (!word.substring(0,4).equals("Stir")) { System.out.println("Enter a word longer than 4 characters, and press q to quit"); scan.next(); } } } } Here I need to print how many words entered by the user contain the substring 'Stir.' However I'm not sure how to get this to work, or if I've done any of it right in the first place! Thanks for any help!

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  • get a different file name

    - by Power-Mosfet
    Hi, How do i get a different file name on a webserver by requesting the url. for example "file" click url link and get "file.bin" the "file" is located on a webserver by requesting the url, user can download "file.bin" instead of "file" something like (file + .bin)

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  • Add other components to JFrame with background

    - by bnabilos
    Hello, I want to add a background image to my JFrame but when I do it using the code below, I'm unable to add other elements like JLabel or JTextField. ImageIcon icon = new ImageIcon("src/images/back.jpg"); backImage = icon.getImage(); BackgroundImagePanel contentPane = new BackgroundImagePanel(); contentPane.setBackgroundImage(backImage); this.setContentPane(contentPane); Can you tell me please if there is another way to add JTabbedPane to a JFrame with a background ? Thank you.

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  • Figuring out QuadCurveTo's parameters

    - by Fev
    Could you guys help me figuring out QuadCurveTo's 4 parameters , I tried to find information on http://docs.oracle.com/javafx/2/api/javafx/scene/shape/QuadCurveTo.html, but it's hard for me to understand without picture , I search on google about 'Quadratic Bezier' but it shows me more than 2 coordinates, I'm confused and blind now. I know those 4 parameters draw 2 lines to control the path , but how we know/count exactly which coordinates the object will throught by only knowing those 2 path-controller. Are there some formulas? import javafx.animation.PathTransition; import javafx.animation.PathTransition.OrientationType; import javafx.application.Application; import static javafx.application.Application.launch; import javafx.scene.Group; import javafx.scene.Scene; import javafx.scene.paint.Color; import javafx.scene.shape.MoveTo; import javafx.scene.shape.Path; import javafx.scene.shape.QuadCurveTo; import javafx.scene.shape.Rectangle; import javafx.stage.Stage; import javafx.util.Duration; public class _6 extends Application { public Rectangle r; @Override public void start(final Stage stage) { r = new Rectangle(50, 80, 80, 90); r.setFill(javafx.scene.paint.Color.ORANGE); r.setStrokeWidth(5); r.setStroke(Color.ANTIQUEWHITE); Path path = new Path(); path.getElements().add(new MoveTo(100.0f, 400.0f)); path.getElements().add(new QuadCurveTo(150.0f, 60.0f, 100.0f, 20.0f)); PathTransition pt = new PathTransition(Duration.millis(1000), path); pt.setDuration(Duration.millis(10000)); pt.setNode(r); pt.setPath(path); pt.setOrientation(OrientationType.ORTHOGONAL_TO_TANGENT); pt.setCycleCount(4000); pt.setAutoReverse(true); pt.play(); stage.setScene(new Scene(new Group(r), 500, 700)); stage.show(); } public static void main(String[] args) { launch(args); } } You can find those coordinates on this new QuadCurveTo(150.0f, 60.0f, 100.0f, 20.0f) line, and below is the picture of Quadratic Bezier

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  • Can I replicate some of the optimisations done by the JVM by hand?

    - by Subb
    I'm working on a Sudoku solver at school and we're having a little performance contest. Right now, my algorithm is pretty fast on the first run (about 2.5ms), but even faster when I solve the same puzzle 10 000 times (about 0.5ms for each run). Those timing are, of course, depend of the puzzle being solved. I know the JVM do some optimization when a method is called multiple time, and this is what I suspect is happening. I don't think I can further optimize the algorithm itself (though I'll keep looking), so I was wondering if I could replicate some of the optimizations done by the JVM. Note : compiling to native code is not an option Thanks!

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  • What is the best way to restore(rollback) data in an application to a specified state(date) ?

    - by panzerschreck
    Hello, An example would set the context right, the example below captures the various states of the entity, which needs to be reverted(rolled back) . State 1 - Recorded on 01-Mar-2010 Column1 Column2 Data1 0.56 State 2 - Recorded on 02-Mar-2010 Column1 Column2 Data1 0.57 State 3 - Recorded on 03-Mar-2010 Column1 Column2 Data1 0.58 User notices that state3 is not what he intended to be in, decides to revert back to state2. One approach that I can think of, without modifying the entity is via "auditing" all the inserts/updates, as below, the rollback information captures the data just before the updates/modifications on the entity, so that it can be applied in an order when you need to revert.Please note that changing the entity's schema, is not an option. Rollback - R1 recorded on 01-Mar-2010 Column1 Column2 Data1 0.56 Rollback - R2 Recorded on 02-Mar-2010 Column1 Column2 Data1 0.56 Rollback - R3 Recorded on 03-Mar-2010 Column1 Column2 Data1 0.57 So, to get to state2 , we would start with rollback information R1,apply R2 onto it. Is there a better approach to achieve this ? Thanks for your time.

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  • How do I manipulate a tree of immutable objects?

    - by Frederik
    I'm building an entire application out of immutable objects so that multi-threading and undo become easier to implement. I'm using the Google Collections Library which provides immutable versions of Map, List, and Set. My application model looks like a tree: Scene is a top-level object that contains a reference to a root Node. Each Node can contain child Nodes and Ports. An object graph might look like this: Scene | +-- Node | +-- Node | +- Port +-- Node | +- Port +- Port If all of these objects are immutable, controlled by a top-level SceneController object: What is the best way to construct this hierarchy? How would I replace an object that is arbitrarily deep in the object tree? Is there a way to support back-links, e.g. a Node having a "parent" attribute?

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  • MySQL Connection Error with JSP

    - by voidmain
    Hello, I am trying to connect to mysql database from jsp page. The connection code is as below InitialContext ic=new InitialContext(); DataSource ds=(DataSource)ic.lookup("jdbc:mysql://localhost:3306/"); Connection con=ds.getConnection(); Statement stmt = con.createStatement(); when i open the page i get the following error javax.servlet.ServletException: javax.naming.NamingException: Lookup failed for 'jdbc:mysql://localhost:3306/' in SerialContext [Root exception is javax.naming.NameNotFoundException: jdbc:mysql:] can some one please tell me what is wrong with this...

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  • Can I include both Apache Axis 1 and 2 libraries in the same project?

    - by ian_scho_es
    If it sounds like a ridiculous idea then it is. The client only wants to have to install one project on their server. Our web service will be bridging between mobile phones and various SOAP services made in .NET, Apache Axis 1 and 2, which rely on standards to transfer files such as MTOM and DIME. I am looking for an 'architecture' trick, such as develop the Axis 1 calls in a separate project and compile as a jar, to then pass it into the Axis 2 project.... Hmmm. Anything rather than having to download the source code for Axis 1 & 2 and compile them using the same xml libraries, etc. "It can't be done" is an acceptable answer. Thanks!

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  • Spring OpenSessionInViewFilter with @Transactional annotation

    - by Gautam
    This is regarding Spring OpenSessionInViewFilter using with @Transactional annotation at service layer. i went through so many stack overflow post on this but still confused about whether i should use OpenSessionInViewFilter or not to avoid LazyInitializationException It would be great help if somebody help me find out answer to below queries. Is it bad practice to use OpenSessionInViewFilter in application having complex schema. using this filter can cause N+1 problem if we are using OpenSessionInViewFilter does it mean @Transactional not required? Below is my Spring config file <context:component-scan base-package="com.test"/> <context:annotation-config/> <bean id="messageSource" class="org.springframework.context.support.ReloadableResourceBundleMessageSource"> <property name="basename" value="resources/messages" /> <property name="defaultEncoding" value="UTF-8" /> </bean> <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer" p:location="/WEB-INF/jdbc.properties" /> <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close" p:driverClassName="${jdbc.driverClassName}" p:url="${jdbc.databaseurl}" p:username="${jdbc.username}" p:password="${jdbc.password}" /> <bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="configLocation"> <value>classpath:hibernate.cfg.xml</value> </property> <property name="configurationClass"> <value>org.hibernate.cfg.AnnotationConfiguration</value> </property> <property name="hibernateProperties"> <props> <prop key="hibernate.dialect">${jdbc.dialect}</prop> <prop key="hibernate.show_sql">true</prop> <!-- <prop key="hibernate.hbm2ddl.auto">create</prop> --> </props> </property> </bean> <tx:annotation-driven /> <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"> <property name="sessionFactory" ref="sessionFactory" /> </bean>

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  • red5: how can i extend ISharedObject ?

    - by ufk
    Hiya. Red5 uses ISharedObject interface to create shared objects and to operate them. because ISharedObject is an interface I'm having issues extending it. I would like to extend the getAttribute, setAttribute, get{Int/String/Map}Attribute so the values will be checked before entered or pulled out. how is it possible to do so ? thanks

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  • Circular increment: Which is "better"?

    - by Helper Method
    When you have a circular buffer represented as an array, and you need the index to wraparound (i.e., when you reach the highest possible index and increment it), is it "better" to: return (i++ == buffer.length) ? 0: i; Or return i++ % buffer.length; Has using the modulo operator any drawbacks? Is it less readable than the first solution?

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  • Do null SQLite Data fields take up extra memory?

    - by CSharperWithJava
    I'm using the built in sqlite library on the Android platform. I'm considering adding several general purpose fields that users will be able to use for their own custom applications, but these fields will be blank most of the time. My question is, how much overhead will these blank fields add to my database? Do null fields even take up per record memory in sqlite? If so, how much? I don't quite understand the inner workings of a sqlite database.

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