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  • Deleting orphans with JPA

    - by homaxto
    I have a one-to-one relation where I use CascadeType.PERSIST. This has over time build up a huge amount of child records that has not been deleted, to such an extend that it is reflected in the performance. Now I wish to add some code that cleans up the database removing all the child records that are not referenced by a parent. At the moment we are talking 400K+ records, at I need to run the code on all customer installations just to be sure they do not run into the same problem. I think the best solution would be to run a named query (because we support two databases) that deletes the necessary records, and this is where I get into problems, because how should I write it in JPQL? The result I want can be defined like the following sql statement, which unfortunaltely does not run on MySQL. DELETE FROM child c1 WHERE c1.pk NOT IN (SELECT DISTINCT p.pk FROM child c2 JOIN parent p ON p.child = c2.pk);

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  • creational pattern for instances depending on multiple subclass instances

    - by markusw
    I have a problem, for that I was not able to identify a suitable design pattern. I want to create instances depending on a given type that has been passed to a factory method. What I am doing until now is the following: T create(SuperType x) { if (x instanceof SubType1) { // do some stuff and return a new SubType extends T } else if (x instanceof SubType2) { // do some stuff and return a new SubType extends T } else if ... } else { throw new UnSupportedOperationException("nothing defined for " + x); } } It seems not to be best pratice for me. Has anybody an idea how to solve this in a better way?

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  • Example of standalone Apache Qpid (amqp) Junit Test

    - by Wiretap
    Does anyone have an example of using Apache Qpid within a standalone junit test. Ideally I want to be able to create a queue on the fly which I can put/get msgs within my test. So I'm not testing QPid within my test, I'll use integration tests for that, however be very useful to test methods handling msgs with having to mock out a load of services.

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  • problem in adding image to JFrame

    - by firestruq
    Hi, I'm having problems in adding a picture into JFrame, something is missing probebly or written wrong. here are the classes: main class: public class Tester { public static void main(String args[]) { BorderLayoutFrame borderLayoutFrame = new BorderLayoutFrame(); borderLayoutFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); borderLayoutFrame.setSize(600,600); borderLayoutFrame.setVisible(true); } } public class BorderLayoutFrame extends JFrame implements ActionListener { private JButton buttons[]; // array of buttons to hide portions private final String names[] = { "North", "South", "East", "West", "Center" }; private BorderLayout layout; // borderlayout object private PicPanel picture = new PicPanel(); // set up GUI and event handling public BorderLayoutFrame() { super( "Philosofic Problem" ); layout = new BorderLayout( 5, 5 ); // 5 pixel gaps setLayout( layout ); // set frame layout buttons = new JButton[ names.length ]; // set size of array // create JButtons and register listeners for them for ( int count = 0; count < names.length; count++ ) { buttons[ count ] = new JButton( names[ count ] ); buttons[ count ].addActionListener( this ); } add( buttons[ 0 ], BorderLayout.NORTH ); // add button to north add( buttons[ 1 ], BorderLayout.SOUTH ); // add button to south add( buttons[ 2 ], BorderLayout.EAST ); // add button to east add( buttons[ 3 ], BorderLayout.WEST ); // add button to west add( picture, BorderLayout.CENTER ); // add button to center } // handle button events public void actionPerformed( ActionEvent event ) { } } I'v tried to add the image into the center of layout. here is the image class: public class PicPanel extends JPanel { Image img; private int width = 0; private int height = 0; public PicPanel() { super(); img = Toolkit.getDefaultToolkit().getImage("table.jpg"); } public void paintComponent(Graphics g) { super.paintComponents(g); if ((width <= 0) || (height <= 0)) { width = img.getWidth(this); height = img.getHeight(this); } g.drawImage(img,0,0,width,height,this); } } Please your help, what is the problem? thanks BTW: i'm using eclipse, which directory the image suppose to be in?

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  • ExecutorService memory leak on exception

    - by TofuBeer
    I am having a hard time tracking this down since the profiler keeps crashing (hotspot error). Before I go too deep into figuring it out I'd like to know if I really have a problem or not :-) I have a few thread pools created via: Executors.newFixedThreadPool(10); The threads connect to different web sites and, on occasion, I get connection refused and wind up throwing an exception. When I later on call Future.get() to get the result it will then catch the ExecutionException that wraps the exception that was thrown when the connection could not be made. The program uses a fairly constant amount of memory up until the point in time that the exceptions get thrown (they tend to happen in batches when a particular site is overloaded). After that point the memory again remains constant but at a higher level. So my question is along the lines of is the memory behaviour (reported by "top" on Unix) expected because the exceptions just triggered something or do I probably have an actual leak that I'll need to track down? Additionally when Future.get() throws an exception is there anything else I need to do besides catch the exception (such as call Future.cancel() on it)?

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  • Refactored App Engine project - now Eclipse is infinitely building the project without end

    - by Yog
    I renamed some files in my App Engine project and refactored code, changing references to variables. Everything seemed fine until I changed the references in the web.xml for the project. Then I got a complaint about some error with the DataNucleus enhancer and now the project build process is stuck at 22%. I tried stopping Eclipse and restarting but the build process keeps hanging. Any tips on how to clean out whatever it's getting stuck on?

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  • JMF. Create new custom streamdatasource

    - by Afro Genius
    Hi there. I am looking to create a means of building a DataSource object (and hence a Processor) that gets data from a stream instead of a file, RTP, and so on. I am writing a module for a much larger application that is meant to transparently transcode audio data. Going through the JMF docs only specify how to create a source from file however I need to be able to create a source from a stream within my application. Any idea where I can start looking?

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  • fail-fast iterator

    - by joy
    I get this definition : As name suggest fail-fast Iterators fail as soon as they realized that structure of Collection has been changed since iteration has begun. what it mean by since iteration has begun? is that mean after Iterator it=set.iterator() this line of code? public static void customize(BufferedReader br) throws IOException{ Set<String> set=new HashSet<String>(); // Actual type parameter added **Iterator it=set.iterator();**

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  • Apache Commons Net FTPClient and listFiles()

    - by Vladimir
    Can anyone explain me what's wrong with the following code? I tried different hosts, FTPClientConfigs, it's properly accessible via firefox/filezilla... FTPClientConfig config = new FTPClientConfig(FTPClientConfig.SYST_L8); FTPClient client = new FTPClient(); client.configure(config); client.connect("c64.rulez.org"); client.login("anonymous", "anonymous"); client.enterRemotePassiveMode(); FTPFile[] files = client.listFiles(); Assert.assertTrue(files.length > 0);

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  • DB2 Driver Connection Hanging in Glassfish Connection Pool

    - by Ant
    We have an intermittent issue around the DB2 used from a Glassfish connection pool. What happens is this: Under situations where the database (DB2 on ZOS) is under stress, our application (which is a multi-threaded application using connections to DB2 via a Glassfish connection pool) stops doing anything. The following are observed: 1) Looking at the server using JConsole, we can see a thread waiting indefinitely in the DB2 driver's getConnection() method. We can also see that it has gained a lock on a Vector within the driver. Several other threads are also calling the getConnection() method in the driver, and are hanging waiting for the lock on the Vector to be released. 2) Looking at the database itself, we can see that there are connections from the Glassfish server open and waiting to be used. It seems that there is some sort of mismatch between the connection pool on Glassfish and the connections actually open to DB2. Has anyone come across this issue before? Or something similar? If you need any more information that I haven't provided, then please let me know!

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  • Detecting client disconnect in tomcat servlet?

    - by Seth
    How can I detect that the client side of a tomcat servlet request has disconnected? I've read that I should do a response.getOutputStream().print(), then a response.getOutputStream().flush() and catch an IOException, but is there a way I can detect this without writing any data?

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  • Bulding an multi-platform SWT application using Ant

    - by Mridang Agarwalla
    I'm writing an SWT application which can be used on Windows (32/64 bit) and Mac OSX (32/64 bit). Apart from the JRE I rely on the SWT library found here. I can find four versions of the SWT library depending upon my target platforms (as mentioned above). When building my application, how can I compile using the correct SWT Jar? If possible, I'd like to try and avoid hard-coding the Jar version, platform and architecture. The SWT Jars are named like this: swt-win32-x86_64.jar swt-win32-x86_32.jar swt-macosx-x86_32.jar swt-macosx-x86_64.jar (My project will be an open source project. I'd like people to be able to download the source and build it and therefore I've thought of including all the four versions of the SWT Jars in the source distribution. I hope this is the correct approach of publishing code relying on third-part libraries.) Thanks everyone.

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  • How to set an empty value using XPath?

    - by Ricardo
    Using this xml example: <templateitem itemid="5"> <templateitemdata>%ARN%</templateitemdata> </templateitem> <templateitem itemid="6"> <templateitemdata></templateitemdata> </templateitem> I am using XPath to get and set Node values. The code I am using to get the nodes is: private static Node ***getNode***(Document doc, String XPathQuery) throws XPathExpressionException { XPath xpath = XPathFactory.newInstance().newXPath(); XPathExpression expr = xpath.compile(XPathQuery); Object result = expr.evaluate(doc, XPathConstants.NODESET); NodeList nodes = (NodeList) result; if(nodes != null && nodes.getLength() >0) return nodes.item(0); throw new XPathExpressionException("No node list found for " + XPathQuery); } To get %ARN% value: "//templateitem[@itemid=5]/templateitemdata/text()" and with the getNode method I can get the node, and then call the getNodeValue(). Besides getting that value, I would like to set templateitemdata value for the "templateitem[@itemid=6]" since its empty. But the code I use can't get the node since its empty. The result is null. Do you know a way get the node so I can set the value?

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  • ExecutionException and InterruptedException while using Future class's get() method

    - by java_geek
    ExecutorService executor = Executors.newSingleThreadExecutor(); try { Task t = new Task(response,inputToPass,pTypes,unit.getInstance(),methodName,unit.getUnitKey()); Future<SCCallOutResponse> fut = executor.submit(t); response = fut.get(unit.getTimeOut(),TimeUnit.MILLISECONDS); } catch (TimeoutException e) { // if the task is still running, a TimeOutException will occur while fut.get() cat.error("Unit " + unit.getUnitKey() + " Timed Out"); response.setVote(SCCallOutConsts.TIMEOUT); } catch (InterruptedException e) { cat.error(e); } catch (ExecutionException e) { cat.error(e); } finally { executor.shutdown(); } } How should i handle the InterruptedException and ExecutionException in the code? And in what cases are these exceptions thrown?

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  • Changing order of children of an SWT Composite

    - by Alexey Romanov
    In my case I have two children of a SashForm, but the question applies to all Composites and different layouts. class MainWindow { Sashform sashform; Tree child1 = null; Table child2 = null; MainWindow(Shell shell) { sashform = new SashForm(shell, SWT.NONE); } // Not called from constructor because it needs data not available at that time void CreateFirstChild() { ... Tree child1 = new Tree(sashform, SWT.NONE); } void CreateSecondChild() { ... Table child2 = new Table(sashform, SWT.NONE); } } I don't know in advance in what order these methods will be called. How can I make sure that child1 is placed on the left, and child2 on the right? Alternately, is there a way to change their order as children of sashform after they are created? Currently my best idea is to put in placeholders like this: class MainWindow { Sashform sashform; private Composite placeholder1; private Composite placeholder2; Tree child1 = null; Table child2 = null; MainWindow(Shell shell) { sashform = new SashForm(shell, SWT.NONE); placeholder1 = new Composite(sashform, SWT.NONE); placeholder2 = new Composite(sashform, SWT.NONE); } void CreateFirstChild() { ... Tree child1 = new Tree(placeholder1, SWT.NONE); } void CreateSecondChild() { ... Table child2 = new Table(placeholder2, SWT.NONE); } }

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  • Strange profiling results: definitely non-bottleneck method pops up

    - by jkff
    I'm profiling a program using sampling profiling in YourKit and JProfiler, and also "manually" (I launch it and press Ctrl-Break several times to get thread dumps). All three methods give me extremely strange results: some tens of percents of time spent in a 3-line method that does not even do any allocation or synchronization and doesn't have loops etc. Moreover, after I made this method into a NOP and even removed its invocation completely, the observable program performance didn't change at all (although it got a negligible memory leak, since it was a method for freeing a cheap resource). I'm thinking that this might be because of the constraints that JVM puts on the moments at which a thread's stacktrace may be taken, and it somehow turns out that in my program it is exactly the moments where this method is invoked, although there is absolutely nothing special about it or the context in which it is invoked. What can be the explanation for this phenomenon? What are the aforementioned constraints? What further measurements can I take to clarify the situation?

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  • Update database settings in properties file in Spring

    - by mvg
    Hi all, I am trying to create a Database Manager page which shows the database details on page load and updates the database settings when the user press submit I followed this tutorial and set the database settings in properties file. I managed to update the database settings in properties file programmatically. When I retrieved the database settings using the following code DriverManagerDataSource databaseSource = (DriverManagerDataSource)context.getBean("dataSource"); databaseSource.getUsername(); I managed to get the old value and unable to get the new value This is the mapping in applicationContext.xml file <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="location"> <value>classpath:/bundle/database.properties</value> </property> </bean> <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName" value="${jdbc.driverClassName}" /> <property name="url" value="${jdbc.url}" /> <property name="username" value="${jdbc.username}" /> <property name="password" value="${jdbc.password}" /> </bean> I checked the properties file and found it to be updated with the latest input. What am I missing? Thanks in advance P.S I am using JSF1.2 with Spring 3 Update Just making my requirement simple. I am creating a setparate dbsettings page, so that when user wishes to connect to different database he/she can just enter the details in dbsettings page and connect

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  • JSF 2.0 method invocation with argument from var of dataGrid

    - by little_b
    Hello I use primefaces with facelets and i have a quastion: for example i have dataGrid and i want to call method of bean, that registered in faces-config, to include some dynamic content: <p:dataGrid var="provider" value="#{paymentFormBean.providers}"> <ui:include src="contentFactory.getSpecificForm('some attribute')"/> </p:dataGrid> How could i invoke getSpecificForm method with argument from var of dataGrid? Something like: <p:dataGrid var="provider" value="#{paymentFormBean.providers}"> <ui:include src="contentFactory.getSpecificForm(provider.formName)"/> </p:dataGrid> Could anyone help me? Thank you

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  • Arrays of different types

    - by Tyler
    Hi - Is it possible to have an array that contains two different types of data? I want to have an array that contains a double and also a string. I attempted: ArrayList<double><String> array; But that didn't work. Sorry for the silly question, but it has been a while since I have used something like this.. Can you refresh my memory on how would I declare and populate such an array? And then to take it a step further, I would like to sort the array by the double if possible? Thanks!

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  • Restrict number of lines in html JLabel

    - by Mike
    I have a JLabel that needs to display some html-formatted text. However, I want to restrict this to being 4 lines long (and if so, provide a button to see everything). So far, I've tried setting the maximum size manually or via a layout manager. However, both of these solutions can cause part of a line to be displayed.

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  • JDO, GAE: Load object group by child's key

    - by tiex
    I have owned one-to-many relationship between two objects: @PersistenceCapable(identityType = IdentityType.APPLICATION) public class AccessInfo { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private com.google.appengine.api.datastore.Key keyInternal; ... @Persistent private PollInfo currentState; public AccessInfo(){} public AccessInfo(String key, String voter, PollInfo currentState) { this.voter = voter; this.currentState = currentState; setKey(key); // this key is unique in whole systme } public void setKey(String key) { this.keyInternal = KeyFactory.createKey( AccessInfo.class.getSimpleName(), key); } public String getKey() { return this.keyInternal.getName(); } and @PersistenceCapable(identityType = IdentityType.APPLICATION) public class PollInfo { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key key; @Persistent(mappedBy = "currentState") private List<AccessInfo> accesses; ... I created an instance of class PollInfo and make it persistence. It is ok. But then I want to load this group by AccessInfo key, and I am getting exception NucleusObjectNotFoundException. Is it possible to load a group by child's key?

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