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  • Performance implications of finalizers on JVM

    - by Alexey Romanov
    According to this post, in .Net, Finalizers are actually even worse than that. Besides that they run late (which is indeed a serious problem for many kinds of resources), they are also less powerful because they can only perform a subset of the operations allowed in a destructor (e.g., a finalizer cannot reliably use other objects, whereas a destructor can), and even when writing in that subset finalizers are extremely difficult to write correctly. And collecting finalizable objects is expensive: Each finalizable object, and the potentially huge graph of objects reachable from it, is promoted to the next GC generation, which makes it more expensive to collect by some large multiple. Does this also apply to JVMs in general and to HotSpot in particular?

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  • JSF: attach rich:toggleControl to radio buttons or select items.

    - by arw
    Has anyone had any success attaching a rich:toggleControl component to a radio button component (h:selectOneRadio) or alternatively any of its children select items (in this case s:enumItem). Basic code example: <h:selectOneRadio value="#{backingValue}"> <s:enumItem enumValue="VAL_1" itemLabel="Value One" /> <s:enumItem enumValue="VAL_2" itemLabel="Value Two" /> <s:convertEnum /> </h:selectOneRadio> The ideal thing would be to attach the toggle control to the enumItems so I could have it switch to a particular state. However at this point I'd be happy if the toggle control can just be attached to the selectOneRadio. I've tried the toggle control as a child of the selectOneRadio and enumItems; neither works. I've also tried wrapping the toggleControl around the selectOneRadio, the toggle control works in this case but the radio buttons don't :(

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  • Maven Ant BuildException with maven-antrun-plugin ... unable to find javac compiler

    - by robsbobs
    Im trying to make Maven call an ANT build for some legacy code. the ant build builds correctly through ant however when i call it using the maven ant plugin it fails with the following error: [ ERROR] Failed to execute goal org.apache.maven.plugins:maven-antrun-plugin:1.6:run (default) on project CoreServices: An Ant BuildException has occured: The following error occurred while executing this line: [ERROR] C:\dev\projects\build\build.xml:158: The following error occurred while executing this line: [ERROR] C:\dev\projects\build\build.xml:62: The following error occurred while executing this line: [ERROR] C:\dev\projects\build\build.xml:33: The following error occurred while executing this line: [ERROR] C:\dev\projects\ods\build.xml:41: Unable to find a javac compiler; [ERROR] com.sun.tools.javac.Main is not on the classpath. [ERROR] Perhaps JAVA_HOME does not point to the JDK. [ERROR] It is currently set to "C:\bea\jdk150_11\jre" My javac exists at C:\bea\jdk150_11\bin and this works for all other things. Im not sure where Maven is getting this version of JAVA_HOME. JAVA_HOME in windows envionrmental variables is set to C:\bea\jdk150_11\ as it should be. The Maven code that im using to call the build.xml is <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-antrun-plugin</artifactId> <version>1.6</version> <executions> <execution> <phase>install</phase> <configuration> <target> <ant antfile="../build/build.xml" target="deliver" > </ant> </target> </configuration> <goals> <goal>run</goal> </goals> </execution> </executions> </plugin> </plugins> </build>

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  • Looking for android Facebook SDK examples...

    - by brybam
    I've looked all over the internet and can't seem to find what i'm looking for... I'm just trying to find a site with some examples on how to use the OFFICIAL facebook android SDK http://github.com/facebook/facebook-android-sdk To be specific i'd like to see some examples on notification use and simple photo upload. But i'll take anything to help get a feel for using the SDK. If anyone knows of any examples please share thank you so much!

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  • How can I get the name of all tables in a JavaDB database?

    - by Jonas
    How can i programmatically get the names of all tables in a JavaDB database? Is there any specific SQL-statement over JDBC I can use for this or any built in function in JDBC? I will use it for exporting the tables to XML, and would like to do it this way so I don't miss any tables from the database when exporting.

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  • Creating custom Android project templates in Eclipse?

    - by Rich
    Every app I make starts out with a number of common base classes, interfaces, utility classes and a basic package structure that has been working for me. Is there a way for me to set up a project template in Eclipse that will give me all of the basic Android project stuff PLUS a bunch of custom packages, classes and interfaces? I guess I could just put all of this stuff into one or more libraries as opposed to creating a whole project template, so if you have a preferred approach or information/links/etc on how to do any of the above, please share (I'm relatively inexperienced with Eclipse, so the more detail the better). Thanks.

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  • Hibernate/JPA DB Schema Generation Best Practices

    - by Bytecode Ninja
    I just wanted to hear the opinion of Hibernate experts about DB schema generation best practices for Hibernate/JPA based projects. Especially: What strategy to use when the project has just started? Is it recommended to let Hibernate automatically generate the schema in this phase or is it better to create the database tables manually from earliest phases of the project? Pretending that throughout the project the schema was being generated using Hibernate, is it better to disable automatic schema generation and manually create the database schema just before the system is released into production? And after the system has been released into production, what is the best practice for maintaining the entity classes and the DB schema (e.g. adding/renaming/updating columns, renaming tables, etc.)? Thanks in advance.

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  • Testing code that uses SoftReference<T>

    - by bmargulies
    To get any code with SoftReference<T> to be fully tested, one must come up with some way to test the 'yup, it's been nulled' case. One might more or less mock this by using a 'for-test' code path to force the reference to be null, but that won't manage the queue exactly as the GC does. I wonder if anyone out can share experience in setting up a repeatable, controlled, environment, in which the GC is, in fact, provoked into collecting and nulling?

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  • Ref to map vs. map to refs vs. multiple refs

    - by mikera
    I'm working on a GUI application in Swing+Clojure that requires various mutable pieces of data (e.g. scroll position, user data, filename, selected tool options etc.). I can see at least three different ways of handling this set of data: Create a ref to a map of all the data: (def data (ref { :filename "filename.xml" :scroll [0 0] })) Create a map of refs to the individual data elements: (def datamap { :filename (ref "filename.xml") :scroll (ref [0 0]) })) Create a separate ref for each in the namespace: (def scroll (ref [0 0])) (def filename (ref "filename.xml")) Note: This data will be accessed concurrently, e.g. by background processing threads or the Swing event handling thread. However there probably isn't a need for consistent transactional updates of multiple elements. What would be your recommended approach and why?

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  • Spring Form: Submitting extra parameter on submit buttons

    - by theringostarrs
    Hi, I am working on a form with a bunch of selection criteria that will generate a report when the form is submitted. I also have a number of different reports that can be generated form this same criteria, and want the type of report to be selectable by using a tab system where each tab clicked on submits the form and generates the correct report. I was to do this by passing an extra parameter into the form to switch onto the right form type I am new to Spring, and from the guidance of an elder was told to use an input button for each tab with the following approximate syntax: <input type="submit" name="${form.selectionValues.tabSelection}" value="1" /> tabSelection form property of the SelectionValues object is not being set. I wasn't surprised ;) DIdn't think this would work. So I am wondering how can I can submit a post back from a button in Spring containing the form values plus an extra tabSelection parameter and value? How should I mark up this mechanism? Will I have to do anything to the form controller to register this extra parameter? The original markup I was using to build this page, was using HTML anchor tags instead of buttons for the tab links, which would be much better for the CSS, is there any way to trigger a full form submit using an anchor href? I know this will be a GET request instead of a POST, and not associated with the form.. so I dont expect this to work.. just trying to think of solutions! I would prefer to use the priginal markup, as the styles are there. Any help would be appreciated

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  • Stacking a View with the Editor Area?

    - by Patrick
    Hello everybody, :-) Is it possible, when developing an Eclipse RCP Application, to stack a view with the editor area? Like this? http://www.fotos-hochladen.net/stackingaviewwithane9e1fdbvp.png I have multiple lists / tables. I want to create a kind of preview composite. When an Item on a list is selected by single mouse click, i want my preview composite to show the data of the item. If the user double clicks an item, i want to open an editor in the stack behind the preview composite. Is there anyway to achieve this? Thanks Patrick :-)

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  • Pointers, links, object and reference count

    - by EugeneP
    String a = "a"; // allocate memory and write address of a memory block to a variable String b = "b"; // in a and b hold addresses b = a; // copy a address into b. // Now what? b value is completely lost and will be garbage collected //* next step a = null; // now a does not hold a valid address to any data, // still data of a object exist somewhere, yet we cannot get access to it. Correct me if there's a mistake somewhere in my reflexions. My question is: suppose anInstance object of type Instance has a property ' surname ' anInstance.getSurname() returns "MySurname". now String s = anInstance.getSurname(); anInstance = null; question is - is it true that getSurname value, namely MySurname will not be garbage collected because and only because it has active reference counter 0, and if other properties of anInstance have a zero reference counter, they'll be garbage collected?

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  • Use ObjectOutputStream and FileOutputStream with FileWriter

    - by wishi
    Hi! Is there any way to use ObjectOutputStream like this: <tag>output of the ObjectOutputStream</tag> If I try: FileOutputStream fos = new FileOutputStream(filename); ObjectOutputStream oos = new ObjectOutputStream(fos); FileWriter fw = new FileWriter(fos); And for example: fw.write("<tag>"); oos.write(cool_object); fw.wrote("</tag>"); I don't get that result. It seems the ObjectOutputStream overwrites the file completly each and every time.

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  • ANDROID : how to get value stored in ArrayList<HashMap<key,value>>?

    - by Roshni Kyada
    I have ArrayList. At another activity i want to access all values stored in ArrayList. I tried following code. ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>(); for(Hashmap<String, String> map: mylist) { for(Entry<String, String> mapEntry: map) { String key = mapEntry.getKey(); String value = mapEntry.getValue(); } } but it shows an error at for(Entry mapEntry: map) that it only interate over Array.

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  • inserted in multiple tables of database at a time

    - by rajkumari
    can we work with multiple tables of database with same connection object of database at same time . suppose i have inserted value in table 1 and at same time also inserted value in table 2 of data base with same object of data base connection. I am using sqlite database in code and getting database locked exception while commit() .

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  • Using HSQLDB in production environments

    - by lewap
    I want to use HSQLDB in a production environment for stroring some data in memory and for data export using files. Does anybody have experience with using hsqldb in production environments? Is hsqldb treating server resources gracefully and does it cleanup unused resources properly?

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  • Android HTTP Connection

    - by Ubersoldat
    Can anybody tell my why this doesn't work in the Android emulator? From the browser I have access and the server is internal. All I can think of is that I'm missing some configuration on my app so it can access the network layer. try { InetAddress server = Inet4Address.getByName("thehost"); //Doesn't work either //or InetAddress server2 = Inet4Address.getByAddress(new String("192.168.1.30").getBytes()); if(server.isReachable(5000)){ Log.d(TAG, "Ping!"); } Socket clientsocket = new Socket(server, 8080); } catch (UnknownHostException e) { Log.e(TAG, "Server Not Found"); } catch (IOException e) { Log.e(TAG, "Couldn't open socket"); } Throws an UnknownHostException Thanks

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  • How to center elements in the BoxLayout using center of the element?

    - by Roman
    I use outputPanel.setLayout(new BoxLayout(outputPanel, BoxLayout.Y_AXIS)); and then I add elements (for example JLabels, JButtons) to the outputPanel. For example: outputPanel.add(submitButton);. I see that all added elements are "centered". It is good, because I do want my elements to be in the center. When I write "center" I mean "equal distance from left and right". But the problem is that the left part of the element is put into the center. And I want to have center of elements to be put into the center. How can I get this behavior?

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  • How to get icons for entities from eclipse?

    - by fastcodejava
    I am writing an eclipse plugin. How do I get the various images from eclipse library? So I don't have have keep a local set of images for the standard entities, e.g classes, interfaces, junits, etc. EDIT : I used PlatformUI.getWorkbench().getSharedImages().getImage(ISharedImages.IMG_OBJ_FILE) from the article : http://www.eclipse.org/articles/Article-Using%20Images%20In%20Eclipse/Using%20Images%20In%20Eclipse.html. That did not work.

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  • Which use cases make temporary JMS queues a better choice than persistent queues?

    - by Stephen Harmon
    When you are designing a JMS application, which use cases make you pick temporary queues over persistent queues? We use temporary queues for response messages. We're having some issues maintaining connections to the temp queues, though, so I am testing persistent response queues, instead. One clear disadvantage of persistent queues is that your application has to "know" about them beforehand. If that's not a big deal, though, are there use cases where temp queues are the obvious choice?

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  • Conditionally required jsf validation in a4j form

    - by volothamp
    Hello, I'm having a little problem with using conditionally evaluated expression in jsf/a4j Here's my code <a4j:form> <h:inputText id="id1" value="#{mybean.myvalue}" size="1" required="#{not mybean.condition}" rendered="#{not mybean.condition}" requiredMessage="Put a number in here" /> <h:selectBooleanCheckbox value="#{mybean.condition}"> <a4j:support event="onclick" reRender="id1"/> </h:selectBooleanCheckbox> <a4j:commandButton action="#{mybean.myaction}" value="Do something" /> </a4j:form> The boolean checkbox conditionally enable/disable the validation. This doesn't work: the a4j:commandButton simply skip the validation. Thanks.

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