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• Hadoop/MapReduce: Reading and writing classes generated from DDL

  - by Dave

  Hi, Can someone walk me though the basic work-flow of reading and writing data with classes generated from DDL? I have defined some struct-like records using DDL. For example: class Customer { ustring FirstName; ustring LastName; ustring CardNo; long LastPurchase; } I've compiled this to get a Customer class and included it into my project. I can easily see how to use this as input and output for mappers and reducers (the generated class implements Writable), but not how to read and write it to file. The JavaDoc for the org.apache.hadoop.record package talks about serializing these records in Binary, CSV or XML format. How do I actually do that? Say my reducer produces IntWritable keys and Customer values. What OutputFormat do I use to write the result in CSV format? What InputFormat would I use to read the resulting files in later, if I wanted to perform analysis over them?

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• Is there a useDirtyFlag option for Tomcat 6 cluster configuration?

  - by kevinjansz

  In Tomcat 5.0.x you had the ability to set useDirtyFlag="false" to force replication of the session after every request rather than checking for set/removeAttribute calls. <Cluster className="org.apache.catalina.cluster.tcp.SimpleTcpCluster" managerClassName="org.apache.catalina.cluster.session.SimpleTcpReplicationManager" expireSessionsOnShutdown="false" **useDirtyFlag="false"** doClusterLog="true" clusterLogName="clusterLog"> ... The comments in the server.xml stated this may be used to make the following work: <% HashMap map = (HashMap)session.getAttribute("map"); map.put("key","value"); %> i.e. change the state of an object that has already been put in the session and you can be sure that this object still be replicated to the other nodes in the cluster. According to the Tomcat 6 documentation you only have two "Manager" options - DeltaManager & BackupManager ... neither of these seem to allow this option or anything like it. In my testing the default setup: <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/> where you get the DeltaManager by default, it's definitely behaving as useDirtyFlag="true" (as I'd expect). So my question is - is there an equivalent in Tomcat 6? Looking at the source I can see a manager implementation "org.apache.catalina.ha.session.SimpleTcpReplicationManager" which does have the useDirtyFlag but the javadoc comments in this state it's "Tomcat Session Replication for Tomcat 4.0" ... I don't know if this is ok to use - I'm guessing not as it's not mentioned in the main cluster configuration documentation.

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• Is there a Scala version of .irbrc or another way to define some default libraries for REPL use?

  - by Tom Morris

  I've written a little library that uses implicits to add functionality that one only needs when using the REPL in Scala. Ruby has libraries like this - for things like pretty printing, firing up text editors (like the interactive_editor gem which invokes Vim from irb - see this post), debuggers and the like. The library I am trying to write adds some methods to java.lang.Class and java.lang.reflect classes using the 'pimp my library' implicit conversion process to help you go and find documentation (initially, with Google, then later possibly with a JavaDoc/ScalaDoc viewer, and maybe the StackOverflow API eventually!). It's an itch-scratching library: I spend so much time copying and pasting classnames into Google that I figured I may as well automate the process. It is the sort of functionality that developers will want to add to their system for use only in the REPL - they shouldn't really be adding it to projects (partly because it may not be something that their fellow developers want, but also because if you are doing some exploratory development, it may be with just a Scala REPL that's not being invoked by an IDE or build tool). In my case, I want to include a few classes and set up some implicits - include a .jar on the CLASSPATH and import it, basically. In Ruby, this is the sort of thing that you'd add to your .irbrc file. Other REPLs have similar ways of setting options and importing libraries. Is there a similar file or way of doing this for the Scala REPL?

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• Would an immutable keyword in Java be a good idea?

  - by berry120

  Generally speaking, the more I use immutable objects in Java the more I'm thinking they're a great idea. They've got lots of advantages from automatically being thread-safe to not needing to worry about cloning or copy constructors. This has got me thinking, would an "immutable" keyword go amiss? Obviously there's the disadvantages with adding another reserved word to the language, and I doubt it will actually happen primarily for the above reason - but ignoring that I can't really see many disadvantages. At present great care has to be taken to make sure objects are immutable, and even then a dodgy javadoc comment claiming a component object is immutable when it's in fact not can wreck the whole thing. There's also the argument that even basic objects like string aren't truly immutable because they're easily vunerable to reflection attacks. If we had an immutable keyword the compiler could surely recursively check and give an iron clad guarantee that all instances of a class were immutable, something that can't presently be done. Especially with concurrency becoming more and more used, I personally think it'd be good to add a keyword to this effect. But are there any disadvantages or implementation details I'm missing that makes this a bad idea?

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• Using Maven for maintaining product documentation

  - by Waldheinz

  We are using Maven for building a Java server-style application. It consists of several modules (in a single Maven "reactor") which can be plugged together to generate a final product (essentially a .jar) with the features enabled that the customer needs. All the internals are documented using JavaDoc and all, but that's not what you can give to the customer to find out how to get the thing running. Currently we have an OpenOffice document which serves as end-user documentation. I'd like to integrate this documentation into the Maven build process where each module's documentation is maintained (hand-edited) together with the Module's sources and the final document can reference the required Module documentation sections, add some friendly foreword and, if possible at all, can reference into the JavaDocs. Ultimately, the document should be output as a PDF. Is there any experience on Maven plugins can help with this? Is DocBook the right tool? Maybe Latex? Or something completely different? A sound "stick with OpenOffice and some text blocks" could be an answer, too.

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• Mixing menuItem.setIntent with onOptionsItemSelected doesn't work

  - by superjos

  While extending a sample Android activity that fires some other activities from its menu, I came to have some menu items handled within onOptionsItemSelected, and some menu items (that just fired intents) handled by calling setIntent within onCreateOptionsMenu. Basically something like: @Override public boolean onCreateOptionsMenu(Menu menu) { super.onCreateOptionsMenu(menu); menu.add(0, MENU_ID_1, Menu.NONE, R.string.menu_text_1); menu.add(0, MENU_ID_2, Menu.NONE, R.string.menu_text_2); menu.add(0, MENU_ID_3, Menu.NONE, R.string.menu_text_3). setIntent(new Intent(this, MyActivity_3.class)); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { super.onOptionsItemSelected(item); switch (item.getItemId()) { case (MENU_ID_1): // Process menu command 1 ... return true; case (MENU_ID_2): // Process menu command 2 ... // E.g. also fire Intent for MyActivity_2 return true; default: return false; } } Apparently, in this situation the Intent set on MENU_ID_3 is never fired, or anyway the related activity is never started. Android javadoc at some point goes like <<[if you set an intent on a menu item] and nothing else handles the item, then the default behavior will be to [start the activity with the intent]. What does it actually mean "and nothing else handles the item"? Is it enough to return false from onOptionsItemSelected? I also tried not to call super.onOptionsItemSelected(item) at the beginning and only invoke it in the default switch case, but I had same results. Does anyone have any suggestion? Does Android allow to mix the two type of handling? Thanks for your time everyone.

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• Most awkward/misleading method in Java Base API ?

  - by JG

  I was recently trying to convert a string literal into a boolean, when the method "boolean Boolean.getBoolean(String name)" popped out of the auto-complete window. There was also another method ("boolean Boolean.parseBoolean(String s)") appearing right after, which lead me to search to find out what were the differences between these two, as they both seemed to do the same. It turns out that what Boolean.getBoolean(String name) really does is to check if there exists a System property (!) of the given name and if its value is true. I think this is very misleading, as I'm definitely not expecting that a method of Boolean is actually making a call to System.getProperty, and just by looking at the method signature, it sure looks (at least to me) like it should be used to parse a String as a boolean. Sure, the javadoc states it clearly, but I still think the method has a misleading name and is not in the right place. Other primitive type wrappers, such as Integer also have a similar method. Also, it doesn't seem to be a very useful method to belong in the base API, as I think it's not very common to have something like -Darg=true. Maybe it's a good question for a Java position interview: "What is the output of Boolean.getBoolean("true")?". I believe a more appropriate place for those methods would be in the System class, e.g., getPropertyAsBoolean; but again, I still think it's unnecessary to have these methods in the base API. It'd make sense to have these in something like the Properties class, where it's very common to do this kind of type conversions. What do you think of all this ? Also, if there's another "awkward" method that you're aware of, please post it. N.B. I know I can use Boolean.valueOf or Boolean.parseBoolean to convert a string literal into a boolean, but I'm just looking to discuss the API design.

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• Java Equivalent of C++ .dll?

  - by Matt D

  So, I've been programming for a while now, but since I haven't worked on many larger, modular projects, I haven't come across this issue before. I know what a .dll is in C++, and how they are used. But every time I've seen similar things in Java, they've always been packaged with source code. For instance, what would I do if I wanted to give a Java library to someone else, but not expose the source code? Instead of the source, I would just give a library as well as a Javadoc, or something along those lines, with the public methods/functions, to another programmer who could then implement them in their own Java code. For instance, if I wanted to create a SAX parser that could be "borrowed" by another programmer, but (for some reason--can't think of one in this specific example lol) I don't want to expose my source. Maybe there's a login involved that I don't want exploited--I don't know. But what would be the Java way of doing this? With C++, .dll files make it much easier, but I have never run into a Java equivalent so far. (I'm pretty new to Java, and a pretty new "real-world" programmer, in general as well)

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• Google calendar query returns at most 25 entries

  - by Dean Hill

  I'm trying to delete all calendar entries from today forward. I run a query then call getEntries() on the query result. getEntries() always returns 25 entries (or less if there are fewer than 25 entries on the calendar). Why aren't all the entries returned? I'm expecting about 80 entries. As a test, I tried running the query, deleting the 25 entries returned, running the query again, deleting again, etc. This works, but there must be a better way. Below is the Java code that only runs the query once. CalendarQuery myQuery = new CalendarQuery(feedUrl); DateFormat dfGoogle = new SimpleDateFormat("yyyy-MM-dd'T00:00:00'"); Date dt = Calendar.getInstance().getTime(); myQuery.setMinimumStartTime(DateTime.parseDateTime(dfGoogle.format(dt))); // Make the end time far into the future so we delete everything myQuery.setMaximumStartTime(DateTime.parseDateTime("2099-12-31T23:59:59")); // Execute the query and get the response CalendarEventFeed resultFeed = service.query(myQuery, CalendarEventFeed.class); // !!! This returns 25 (or less if there are fewer than 25 entries on the calendar) !!! int test = resultFeed.getEntries().size(); // Delete all the entries returned by the query for (int j = 0; j < resultFeed.getEntries().size(); j++) { CalendarEventEntry entry = resultFeed.getEntries().get(j); entry.delete(); } PS: I've looked at the Data API Developer's Guide and the Google Data API Javadoc. These sites are okay, but not great. Does anyone know of additional Google API documentation?

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• JVM terminated. Exit code = -1

  - by Lex

  Hello, I've been using Eclipse for some time already, and I didn't have any problems with it. However, when I tried to generate some javadoc, I found that I didn't have the SDK installed. I installed jdk 6u23, and from then on, Eclipse hasn't been working. At first it told me it couldn't find a JRE/SDK. After copying and placing the JRE in the Eclipse folder, the error changed to this: http://i258.photobucket.com/albums/hh261/magical_7/Eclipse.png I've searched around for some solutions, and found a few of varying nature. However, none of them seemed to work. I've tried emptying my eclipse.ini file without success. Altering some values in eclipse.ini didn't work either. Installing Java SDK 1.5 didn't work. Does anyone have other possible solutions? Update: I tried reinstalling Eclipse, but it didn't fix the problem. I did notice that it's a 32bit version, while I'm running a 64bit system. However, if this were to be the problem, I find it strange that it hasn't been an issue earlier.

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• Why does java.util.concurrent.ArrayBlockingQueue use 'while' loops instead of 'if' around calls to

  - by theFunkyEngineer

  I have been playing with my own version of this, using 'if', and all seems to be working fine. Of course this will break down horribly if signalAll() is used instead of signal(), but if only one thread at a time is notified, how can this go wrong? Their code here - check out the put() and take() methods; a simpler and more-to-the-point implementation can be seen at the top of the JavaDoc for Condition. Relevant portion of my implementation below. public Object get() { lock.lock(); try { if( items.size() < 1 ) hasItems.await(); Object poppedValue = items.getLast(); items.removeLast(); hasSpace.signal(); return poppedValue; } catch (InterruptedException e) { e.printStackTrace(); return null; } finally { lock.unlock(); } } public void put(Object item) { lock.lock(); try { if( items.size() >= capacity ) hasSpace.await(); items.addFirst(item); hasItems.signal(); return; } catch (InterruptedException e) { e.printStackTrace(); } finally { lock.unlock(); } } P.S. I know that generally, particularly in lib classes like this, one should let the exceptions percolate up.

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• JDK bug migration: components and subcomponents

  - by darcy

  One subtask of the JDK migration from the legacy bug tracking system to JIRA was reclassifying bugs from a three-level taxonomy in the legacy system, (product, category, subcategory), to a fundamentally two-level scheme in our customized JIRA instance, (component, subcomponent). In the JDK JIRA system, there is technically a third project-level classification, but by design a large majority of JDK-related bugs were migrated into a single "JDK" project. In the end, over 450 legacy subcategories were simplified into about 120 subcomponents in JIRA. The 120 subcomponents are distributed among 17 components. A rule of thumb used was that a subcategory had to have at least 50 bugs in it for it to be retained. Below is a listing the component / subcomponent classification of the JDK JIRA project along with some notes and guidance on which OpenJDK email addresses cover different areas. Eventually, a separate incidents project to host new issues filed at bugs.sun.com will use a slightly simplified version of this scheme. The preponderance of bugs and subcomponents for the JDK are in library-related areas, with components named foo-libs and subcomponents primarily named after packages. While there was an overall condensation of subcomponents in the migration, in some cases long-standing informal divisions in core libraries based on naming conventions in the description were promoted to formal subcomponents. For example, hundreds of bugs in the java.util subcomponent whose descriptions started with "(coll)" were moved into java.util:collections. Likewise, java.lang bugs starting with "(reflect)" and "(proxy)" were moved into java.lang:reflect. client-libs (Predominantly discussed on 2d-dev and awt-dev and swing-dev.) 2d demo java.awt java.awt:i18n java.beans (See beans-dev.) javax.accessibility javax.imageio javax.sound (See sound-dev.) javax.swing core-libs (See core-libs-dev.) java.io java.io:serialization java.lang java.lang.invoke java.lang:class_loading java.lang:reflect java.math java.net java.nio (Discussed on nio-dev.) java.nio.charsets java.rmi java.sql java.sql:bridge java.text java.util java.util.concurrent java.util.jar java.util.logging java.util.regex java.util:collections java.util:i18n javax.annotation.processing javax.lang.model javax.naming (JNDI) javax.script javax.script:javascript javax.sql org.openjdk.jigsaw (See jigsaw-dev.) security-libs (See security-dev.) java.security javax.crypto (JCE: includes SunJCE/MSCAPI/UCRYPTO/ECC) javax.crypto:pkcs11 (JCE: PKCS11 only) javax.net.ssl (JSSE, includes javax.security.cert) javax.security javax.smartcardio javax.xml.crypto org.ietf.jgss org.ietf.jgss:krb5 other-libs corba corba:idl corba:orb corba:rmi-iiop javadb other (When no other subcomponent is more appropriate; use judiciously.) Most of the subcomponents in the xml component are related to jaxp. xml jax-ws jaxb javax.xml.parsers (JAXP) javax.xml.stream (JAXP) javax.xml.transform (JAXP) javax.xml.validation (JAXP) javax.xml.xpath (JAXP) jaxp (JAXP) org.w3c.dom (JAXP) org.xml.sax (JAXP) For OpenJDK, most JVM-related bugs are connected to the HotSpot Java virtual machine. hotspot (See hotspot-dev.) build compiler (See hotspot-compiler-dev.) gc (garbage collection, see hotspot-gc-dev.) jfr (Java Flight Recorder) jni (Java Native Interface) jvmti (JVM Tool Interface) mvm (Multi-Tasking Virtual Machine) runtime (See hotspot-runtime-dev.) svc (Servicability) test core-svc (See serviceability-dev.) debugger java.lang.instrument java.lang.management javax.management tools The full JDK bug database contains entries related to legacy virtual machines that predate HotSpot as well as retired APIs. vm-legacy jit (Sun Exact VM) jit_symantec (Symantec VM, before Exact VM) jvmdi (JVM Debug Interface ) jvmpi (JVM Profiler Interface ) runtime (Exact VM Runtime) Notable command line tools in the $JDK/bin directory have corresponding subcomponents. tools appletviewer apt (See compiler-dev.) hprof jar javac (See compiler-dev.) javadoc(tool) (See compiler-dev.) javah (See compiler-dev.) javap (See compiler-dev.) jconsole launcher updaters (Timezone updaters, etc.) visualvm Some aspects of JDK infrastructure directly affect JDK Hg repositories, but other do not. infrastructure build (See build-dev and build-infra-dev.) licensing (Covers updates to the third party readme, licenses, and similar files.) release_eng (Release engineering) staging (Staging of web pages related to JDK releases.) The specification subcomponent encompasses the formal language and virtual machine specifications. specification language (The Java Language Specification) vm (The Java Virtual Machine Specification) The code for the deploy and install areas is not currently included in OpenJDK. deploy deployment_toolkit plugin webstart install auto_update install servicetags In the JDK, there are a number of cross-cutting concerns whose organization is essentially orthogonal to other areas. Since these areas generally have dedicated teams working on them, it is easier to find bugs of interest if these bugs are grouped first by their cross-cutting component rather than by the affected technology. docs doclet guides hotspot release_notes tools tutorial embedded build hotspot libraries globalization locale-data translation performance hotspot libraries The list of subcomponents will no doubt grow over time, but my inclination is to resist that growth since the addition of each subcomponent makes the system as a whole more complicated and harder to use. When the system gets closer to being externalized, I plan to post more blog entries describing recommended use of various custom fields in the JDK project.

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• Simple Project Templates

  - by Geertjan

  The NetBeans sources include a module named "simple.project.templates": In the module sources, Tim Boudreau turns out to be the author of the code, so I asked him what it was all about, and if he could provide some usage code. His response, from approximately this time last year because it's been sitting in my inbox for a while, is below. Sure - though I think the javadoc in it is fairly complete.  I wrote it because I needed to create a bunch of project templates for Javacard, and all of the ways that is usually done were grotesque and complicated.  I figured we already have the ability to create files from templates, and we already have the ability to do substitutions in templates, so why not have a single file that defines the project as a list of file templates to create (with substitutions in the names) and some definitions of what should be in project properties. You can also add files to the project programmatically if you want.Basically, a template for an entire project is a .properties file.  Any line which doesn't have the prefix 'pp.' or 'pvp.' is treated as the definition of one file which should be created in the new project.  Any such line where the key ends in * means that file should be opened once the new project is created.  So, for example, in the nodejs module, the definition looks like: {{projectName}}.js*=Templates/javascript/HelloWorld.js .npmignore=node_hidden_templates/npmignore So, the first line means:  - Create a file with the same name as the project, using the HelloWorld template    - I.e. the left side of the line is the relative path of the file to create, and the right side is the path in the system filesystem for the template to use       - If the template is not one you normally want users to see, just register it in the system filesystem somewhere other than Templates/ (but remember to set the attribute that marks it as a template)  - Include that file in the set of files which should be opened in the editor once the new project is created. To actually create a project, first you just create a new ProjectCreator: ProjectCreator gen = new ProjectCreator( parentFolderOfNewProject ); Now, if you want to programmatically generate any files, in addition to those defined in the template, you can: gen.add (new FileCreator("nbproject", "project.xml", false) {     public DataObject create (FileObject project, Map<String,String> substitutions) throws IOException {          ...     } }); Then pass the FileObject for the project template (the properties file) to the ProjectCreator's createProject method (hmm, maybe it should be the string path to the project template instead, to save the caller trouble looking up the FileObject for the template).  That method looks like this: public final GeneratedProject createProject(final ProgressHandle handle, final String name, final FileObject template, final Map<String, String> substitutions) throws IOException { The name parameter should be the directory name for the new project;  the map is the strings you gathered in the wizard which should be used for substitutions.  createProject should be called on a background thread (i.e. use a ProgressInstantiatingIterator for the wizard iterator and just pass in the ProgressHandle you are given). The return value is a GeneratedProject object, which is just a holder for the created project directory and the set of DataObjects which should be opened when the wizard finishes. I'd love to see simple.project.templates moved out of the javacard cluster, as it is really useful and much simpler than any of the stuff currently done for generating projects.  It would also be possible to do much richer tools for creating projects in apisupport - i.e. choose (or create in the wizard) the templates you want to use, generate a skeleton wizard with a UI for all the properties you'd like to substitute, etc. Here is a partial project template from Javacard - for example usage, see org.netbeans.modules.javacard.wizard.ProjectWizardIterator in javacard.project (or the much simpler one in contrib/nodejs). #This properties file describes what to create when a project template is#instantiated.  The keys are paths on disk relative to the project root. #The values are paths to the templates to use for those files in the system#filesystem.  Any string inside {{ and }}'s will be substituted using properties#gathered in the template wizard.#Special key prefixes are #  pp. - indicates an entry for nbproject/project.properties#  pvp. - indicates an entry for nbproject/private/private.properties #File templates, in format [path-in-project=path-to-template]META-INF/javacard.xml=org-netbeans-modules-javacard/templates/javacard.xmlMETA-INF/MANIFEST.MF=org-netbeans-modules-javacard/templates/EAP_MANIFEST.MF APPLET-INF/applet.xml=org-netbeans-modules-javacard/templates/applet.xmlscripts/{{classnamelowercase}}.scr=org-netbeans-modules-javacard/templates/test.scrsrc/{{packagepath}}/{{classname}}.java*=Templates/javacard/ExtendedApplet.java nbproject/deployment.xml=org-netbeans-modules-javacard/templates/deployment.xml#project.properties contentspp.display.name={{projectname}}pp.platform.active={{activeplatform}} pp.active.device={{activedevice}}pp.includes=**pp.excludes= I will be using the above info in an upcoming blog entry and provide step by step instructions showing how to use them. However, anyone else out there should have enough info from the above to get started yourself!

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• Concurrency Utilities for Java EE Early Draft (JSR 236)

  - by arungupta

  Concurrency Utilities for Java EE is being worked as JSR 236 and has released an Early Draft. It provides concurrency capabilities to Java EE application components without compromising container integrity. Simple (common) and advanced concurrency patterns are easily supported without sacrificing usability. Using Java SE concurrency utilities such as java.util.concurrent API, java.lang.Thread and java.util.Timer in a Java EE application component such as EJB or Servlet are problematic since the container and server have no knowledge of these resources. JSR 236 enables concurrency largely by extending the Concurrency Utilities API developed under JSR-166. This also allows a consistency between Java SE and Java EE concurrency programming model. There are four main programming interfaces available: ManagedExecutorService ManagedScheduledExecutorService ContextService ManagedThreadFactory ManagedExecutorService is a managed version of java.util.concurrent.ExecutorService. The implementations of this interface are provided by the container and accessible using JNDI reference: <resource-env-ref>  <resource-env-ref-name>    concurrent/BatchExecutor  </resource-env-ref-name>  <resource-env-ref-type>    javax.enterprise.concurrent.ManagedExecutorService  </resource-env-ref-type><resource-env-ref> and available as: @Resource(name="concurrent/BatchExecutor")ManagedExecutorService executor; Its recommended to bind the JNDI references in the java:comp/env/concurrent subcontext. The asynchronous tasks that need to be executed need to implement java.lang.Runnable or java.util.concurrent.Callable interface as: public class MyTask implements Runnable { public void run() { // business logic goes here }} OR public class MyTask2 implements Callable<Date> {  public Date call() { // business logic goes here   }} The task is then submitted to the executor using one of the submit method that return a Future instance. The Future represents the result of the task and can also be used to check if the task is complete or wait for its completion. Future<String> future = executor.submit(new MyTask(), String.class);. . .String result = future.get(); Another example to submit tasks is: class MyTask implements Callback<Long> { . . . }class MyTask2 implements Callback<Date> { . . . }ArrayList<Callable> tasks = new ArrayList<();tasks.add(new MyTask());tasks.add(new MyTask2());List<Future<Object>> result = executor.invokeAll(tasks); The ManagedExecutorService may be configured for different properties such as: Hung Task Threshold: Time in milliseconds that a task can execute before it is considered hung Pool Info Core Size: Number of threads to keep alive Maximum Size: Maximum number of threads allowed in the pool Keep Alive: Time to allow threads to remain idle when # of threads > Core Size Work Queue Capacity: # of tasks that can be stored in inbound buffer Thread Use: Application intend to run short vs long-running tasks, accordingly pooled or daemon threads are picked ManagedScheduledExecutorService adds delay and periodic task running capabilities to ManagedExecutorService. The implementations of this interface are provided by the container and accessible using JNDI reference: <resource-env-ref>  <resource-env-ref-name>    concurrent/BatchExecutor  </resource-env-ref-name>  <resource-env-ref-type>    javax.enterprise.concurrent.ManagedExecutorService  </resource-env-ref-type><resource-env-ref> and available as: @Resource(name="concurrent/timedExecutor")ManagedExecutorService executor; And then the tasks are submitted using submit, invokeXXX or scheduleXXX methods. ScheduledFuture<?> future = executor.schedule(new MyTask(), 5, TimeUnit.SECONDS); This will create and execute a one-shot action that becomes enabled after 5 seconds of delay. More control is possible using one of the newly added methods: MyTaskListener implements ManagedTaskListener {  public void taskStarting(...) { . . . }  public void taskSubmitted(...) { . . . }  public void taskDone(...) { . . . }  public void taskAborted(...) { . . . } }ScheduledFuture<?> future = executor.schedule(new MyTask(), 5, TimeUnit.SECONDS, new MyTaskListener()); Here, ManagedTaskListener is used to monitor the state of a task's future. ManagedThreadFactory provides a method for creating threads for execution in a managed environment. A simple usage is: @Resource(name="concurrent/myThreadFactory")ManagedThreadFactory factory;. . .Thread thread = factory.newThread(new Runnable() { . . . }); concurrent/myThreadFactory is a JNDI resource. There is lot of interesting content in the Early Draft, download it, and read yourself. The implementation will be made available soon and also be integrated in GlassFish 4 as well. Some references for further exploring ... Javadoc Early Draft Specification concurrency-ee-spec.java.net [email protected]

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• Is it feasible and useful to auto-generate some code of unit tests?

  - by skiwi

  Earlier today I have come up with an idea, based upon a particular real use case, which I would want to have checked for feasability and usefulness. This question will feature a fair chunk of Java code, but can be applied to all languages running inside a VM, and maybe even outside. While there is real code, it uses nothing language-specific, so please read it mostly as pseudo code. The idea Make unit testing less cumbersome by adding in some ways to autogenerate code based on human interaction with the codebase. I understand this goes against the principle of TDD, but I don't think anyone ever proved that doing TDD is better over first creating code and then immediatly therafter the tests. This may even be adapted to be fit into TDD, but that is not my current goal. To show how it is intended to be used, I'll copy one of my classes here, for which I need to make unit tests. public class PutMonsterOnFieldAction implements PlayerAction { private final int handCardIndex; private final int fieldMonsterIndex; public PutMonsterOnFieldAction(final int handCardIndex, final int fieldMonsterIndex) { this.handCardIndex = Arguments.requirePositiveOrZero(handCardIndex, "handCardIndex"); this.fieldMonsterIndex = Arguments.requirePositiveOrZero(fieldMonsterIndex, "fieldCardIndex"); } @Override public boolean isActionAllowed(final Player player) { Objects.requireNonNull(player, "player"); Hand hand = player.getHand(); Field field = player.getField(); if (handCardIndex >= hand.getCapacity()) { return false; } if (fieldMonsterIndex >= field.getMonsterCapacity()) { return false; } if (field.hasMonster(fieldMonsterIndex)) { return false; } if (!(hand.get(handCardIndex) instanceof MonsterCard)) { return false; } return true; } @Override public void performAction(final Player player) { Objects.requireNonNull(player); if (!isActionAllowed(player)) { throw new PlayerActionNotAllowedException(); } Hand hand = player.getHand(); Field field = player.getField(); field.setMonster(fieldMonsterIndex, (MonsterCard)hand.play(handCardIndex)); } } We can observe the need for the following tests: Constructor test with valid input Constructor test with invalid inputs isActionAllowed test with valid input isActionAllowed test with invalid inputs performAction test with valid input performAction test with invalid inputs My idea mainly focuses on the isActionAllowed test with invalid inputs. Writing these tests is not fun, you need to ensure a number of conditions and you check whether it really returns false, this can be extended to performAction, where an exception needs to be thrown in that case. The goal of my idea is to generate those tests, by indicating (through GUI of IDE hopefully) that you want to generate tests based on a specific branch. The implementation by example User clicks on "Generate code for branch if (handCardIndex >= hand.getCapacity())". Now the tool needs to find a case where that holds. (I haven't added the relevant code as that may clutter the post ultimately) To invalidate the branch, the tool needs to find a handCardIndex and hand.getCapacity() such that the condition >= holds. It needs to construct a Player with a Hand that has a capacity of at least 1. It notices that the capacity private int of Hand needs to be at least 1. It searches for ways to set it to 1. Fortunately it finds a constructor that takes the capacity as an argument. It uses 1 for this. Some more work needs to be done to succesfully construct a Player instance, involving the creation of objects that have constraints that can be seen by inspecting the source code. It has found the hand with the least capacity possible and is able to construct it. Now to invalidate the test it will need to set handCardIndex = 1. It constructs the test and asserts it to be false (the returned value of the branch) What does the tool need to work? In order to function properly, it will need the ability to scan through all source code (including JDK code) to figure out all constraints. Optionally this could be done through the javadoc, but that is not always used to indicate all constraints. It could also do some trial and error, but it pretty much stops if you cannot attach source code to compiled classes. Then it needs some basic knowledge of what the primitive types are, including arrays. And it needs to be able to construct some form of "modification trees". The tool knows that it needs to change a certain variable to a different value in order to get the correct testcase. Hence it will need to list all possible ways to change it, without using reflection obviously. What this tool will not replace is the need to create tailored unit tests that tests all kinds of conditions when a certain method actually works. It is purely to be used to test methods when they invalidate constraints. My questions: Is creating such a tool feasible? Would it ever work, or are there some obvious problems? Would such a tool be useful? Is it even useful to automatically generate these testcases at all? Could it be extended to do even more useful things? Does, by chance, such a project already exist and would I be reinventing the wheel? If not proven useful, but still possible to make such thing, I will still consider it for fun. If it's considered useful, then I might make an open source project for it depending on the time. For people searching more background information about the used Player and Hand classes in my example, please refer to this repository. At the time of writing the PutMonsterOnFieldAction has not been uploaded to the repo yet, but this will be done once I'm done with the unit tests.

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• read user Input of custom dialogs

  - by urobo

  I built a custom dialog starting from an AlertDialog to obtain login information from a user. So the dialog contains two EditText fields, using the layoutinflater service I obtain the layout and I'm saving a reference to the fields. LayoutInflater inflater = (LayoutInflater) Home.this.getSystemService(LAYOUT_INFLATER_SERVICE); layoutLogin = inflater.inflate(R.layout.login,(ViewGroup) findViewById(R.id.rl)); usernameInput =((EditText)findViewById(R.id.getNewUsername)); passwordInput = ((EditText)findViewById(R.id.getNewPassword)); Then I have my overridden onCreateDialog(...) : { AlertDialog d = null; AlertDialog.Builder builder = new AlertDialog.Builder(this); switch(id){ ... case Home.DIALOG_LOGIN: builder.setView(layoutLogin); builder.setMessage("Sign in to your DyCaPo Account").setCancelable(false); d=builder.create(); d.setTitle("Login"); Message msg = new Message(); msg.setTarget(Home.this.handleLogin); Bundle data = new Bundle(); data.putString("username", usernameInput.getText().toString());// <---null pointer Exception data.putString("password", passwordInput.getText().toString()); msg.setData(data); d.setButton(Dialog.BUTTON_NEUTRAL,"Sign in",msg); break; ... return d; } and the handler set in the Message: private Handler handleLogin= new Handler(){ /* (non-Javadoc) * @see android.os.Handler#handleMessage(android.os.Message) */ @Override public void handleMessage(Message msg) { // TODO Auto-generated method stub Log.d("Message Received", msg.getData().getString("username")+ msg.getData().getString("password")); } }; which for now works as a debugging tool. That's all. The Question is: what am I doing wrong? Because when I reach the line highlighted in the code ( the line in which I read the fields in the dialog ) I always get a null pointer exception. Could somebody please tell me the reason why it is so? And give some guidelines to work with dialogs. Thanks in advance!

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• How to use Broadcast Receiver in different Applications in Android?

  - by Sebi

  Hi I have here two applications in two different projects in eclipse. One application (A) defines an activity (A1) which is started first. Then i start from this activity the second activity (B1) in the second project (B). This works fine. I start it the following way: Intent intent = new Intent("pacman.intent.action.Launch"); intent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP); startActivity(intent); Now i want to send intents bewtween the two activities by using broadcast receivers. In activity A1 i send the intents the following way: Intent intent = new Intent("pacman.intent.action.BROADCAST"); intent.putExtra("message","Wake up."); sendBroadcast(intent); The part of the manifest file in activity A1 that is responsible for this broadcast is the following: <activity android:name="ch.ifi.csg.games4blue.games.pacman.controller.PacmanGame" android:label="@string/app_name"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> <intent-filter> <action android:name="android.intent.action.BROADCAST" /> </intent-filter> </activity> In the receiving activity, I define the receiver the following way in the manifest file: <application android:icon="@drawable/icon" android:label="@string/app_name"> <activity android:name=".PacmanGame" android:label="@string/app_name" android:screenOrientation="portrait"> <intent-filter> <action android:name="pacman.intent.action.Launch" /> <category android:name="android.intent.category.DEFAULT" /> </intent-filter> <receiver android:name="ch.ifi.csg.games4blue.games.pacman.controller.MsgListener" /> </activity> </application> The class message listener is implemented this way: public class MsgListener extends BroadcastReceiver { /* (non-Javadoc) * @see android.content.BroadcastReceiver#onReceive(android.content.Context, android.content.Intent) */ @Override public void onReceive(Context context, Intent intent) { System.out.println("Message at Pacman received!"); } } Unfortunately, the message is never received. Although the method in activity A1 is called, i never receive an intent in B1. Any hints how to solve this? Thanks a lot!

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• How to actually use Swing Application Framework?

  - by Joonas Pulakka

  Hello, I'd like to learn how to effectively use Swing Application Framework. Most of the the examples I've found are blog entries that just explain how to great it is to extend SingleFrameApplication and override its startup method, but that's about it. Sun's article is almost two years old, as is the project's own introduction, and there has apparently been some evolution since then. Are there any recent and thorough tutorials/HOWTOs available anywhere? There is JavaDoc of course, but it's hard to get the big picture from there. Any pointers are appreciated. Update: I realized that there's a mailing list archive at the project's site. While somewhat clumsy (compared to StackOverflow ;) it seems to be quite active. Still it's a pity that there are no real tutorials anywhere. The information is scattered here and there. Update 2: Let me clarify - I'm not having trouble using Swing (the widget toolkit) itself, I'm talking about its Application Framework, which is supposed to ease things like application lifecycle (startup, exit and whatever happens between them), action management etc. - that is, things that most Swing applications will need. It's cool to get such framework to be standard part of Java. The only problem is to learn how it's intended to be used. Update 3: For the interested, there was just some discussion at the project's forum regarding the current state and future of JSR 296. Shortly: the current version 1.03 is considered to be quite usable, but the API is not stable and it will change to the final version in Java 7. The package name will also change so Java 7 will not break current applications made on SAF. Update 4: Karsten Lentzsch stated at the above mentioned forum: "I doubt that it can be included in Java 7; and I'll vote against it.". I would rather not question the sincerity of this great guru, and it's certainly wise not to let anything flawed to slip into the core JDK, but frankly it's a strange situation - he is the author of JGoodies Swing Suite which is partly a commercial competitor of JSR 296, and he is sitting in the committee that will decide whether this JSR will be included to standard Java. It was the same thing with JSR 295 Beans Binding which I wrote about earlier. Given the current state of SAF, I think the best solution is to wrap the current implementation into a "homebrew" framework, which can then accommodate possible changes to the existing API.

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• HttpClient response handler always returns closed stream

  - by Alex Ciminian

  I'm new to Java development so please bear with me. Also, I hope I'm not the champion of tl;dr :). I'm using HttpClient to make requests over Http (duh!) and I'd gotten it to work for a simple servlet that receives an URL as a query string parameter. I realized that my code could use some refactoring, so I decided to make my own HttpResponseHandler, to clean up the code, make it reusable and improve exception handling. I currently have something like this: public class HttpResponseHandler implements ResponseHandler<InputStream>{ public InputStream handleResponse(HttpResponse response) throws ClientProtocolException, IOException { int statusCode = response.getStatusLine().getStatusCode(); InputStream in = null; if (statusCode != HttpStatus.SC_OK) { throw new HttpResponseException(statusCode, null); } else { HttpEntity entity = response.getEntity(); if (entity != null) { in = entity.getContent(); // This works // for (int i;(i = in.read()) >= 0;) System.out.print((char)i); } } return in; } } And in the method where I make the actual request: HttpClient httpclient = new DefaultHttpClient(); HttpGet httpget = new HttpGet(target); ResponseHandler<InputStream> httpResponseHandler = new HttpResponseHandler(); try { InputStream in = httpclient.execute(httpget, httpResponseHandler); // This doesn't work // for (int i;(i = in.read()) >= 0;) System.out.print((char)i); return in; } catch (HttpResponseException e) { throw new HttpResponseException(e.getStatusCode(), null); } The problem is that the input stream returned from the handler is closed. I don't have any idea why, but I've checked it with the prints in my code (and no, I haven't used them both at the same time :). While the first print works, the other one gives a closed stream error. I need InputStreams, because all my other methods expect an InputStream and not a String. Also, I want to be able to retrieve images (or maybe other types of files), not just text files. I can work around this pretty easily by giving up on the response handler (I have a working implementation that doesn't use it), but I'm pretty curious about the following: Why does it do what it does? How do I open the stream, if something closes it? What's the right way to do this, anyway :)? I've checked the docs and I couldn't find anything useful regarding this issue. To save you a bit of Googling, here's the Javadoc and here's the HttpClient tutorial (Section 1.1.8 - Response handlers). Thanks, Alex

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• fileToSTring keeps on returning " "

  - by karikari

  I managed to get this code to compile with out error. But somehow it did not return the strings that I wrote inside file1.txt and file.txt that I pass its path through str1 and str2. My objective is to use this open source library to measure the similarity between strings contains inside 2 text files. Inside the its Javadoc, its states that ... public static java.lang.StringBuffer fileToString(java.io.File f) private call to load a file and return its content as a string. Parameters: f - a file for which to load its content Returns: a string containing the files contents or "" if empty or not present Here's is my modified code trying to use the FileLoader function, but fails to return the strings inside the file. The end result keeps on returning me the "" . I do not know where is my fault: package uk.ac.shef.wit.simmetrics; import java.io.File; import uk.ac.shef.wit.simmetrics.similaritymetrics.*; import uk.ac.shef.wit.simmetrics.utils.*; public class SimpleExample { public static void main(final String[] args) { if(args.length != 2) { usage(); } else { String str1 = "arg[0]"; String str2 = "arg[1]"; File objFile1 = new File(str1); File objFile2 = new File(str2); FileLoader obj1 = new FileLoader(); FileLoader obj2 = new FileLoader(); str1 = obj1.fileToString(objFile1).toString(); str2 = obj2.fileToString(objFile2).toString(); System.out.println(str1); System.out.println(str2); AbstractStringMetric metric = new MongeElkan(); //this single line performs the similarity test float result = metric.getSimilarity(str1, str2); //outputs the results outputResult(result, metric, str1, str2); } } private static void outputResult(final float result, final AbstractStringMetric metric, final String str1, final String str2) { System.out.println("Using Metric " + metric.getShortDescriptionString() + " on strings \"" + str1 + "\" & \"" + str2 + "\" gives a similarity score of " + result); } private static void usage() { System.out.println("Performs a rudimentary string metric comparison from the arguments given.\n\tArgs:\n\t\t1) String1 to compare\n\t\t2)String2 to compare\n\n\tReturns:\n\t\tA standard output (command line of the similarity metric with the given test strings, for more details of this simple class please see the SimpleExample.java source file)"); } }

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• Why fill() and copy() of Collections in java is implemented this way

  - by Priyank Doshi

  According to javadoc... Collections.fill() is written as below : public static <T> void fill(List<? super T> list, T obj) { int size = list.size(); if (size < FILL_THRESHOLD || list instanceof RandomAccess) { for (int i=0; i<size; i++) list.set(i, obj); } else { ListIterator<? super T> itr = list.listIterator(); for (int i=0; i<size; i++) { itr.next(); itr.set(obj); } } } Its easy to understand why they didn't use listIterator for if (size < FILL_THRESHOLD || list instanceof RandomAccess) condition as of RandomAccess. But whats the use of size < FILL_THRESHOLD in above? I mean is there any significant performance benefit over using iterator for size>=FILL_THRESHOLD and not for size < FILL_THRESHOLD ? I see the same approach for Collections.copy() also : public static <T> void copy(List<? super T> dest, List<? extends T> src) { int srcSize = src.size(); if (srcSize > dest.size()) throw new IndexOutOfBoundsException("Source does not fit in dest"); if (srcSize < COPY_THRESHOLD || (src instanceof RandomAccess && dest instanceof RandomAccess)) { for (int i=0; i<srcSize; i++) dest.set(i, src.get(i)); } else { ListIterator<? super T> di=dest.listIterator(); ListIterator<? extends T> si=src.listIterator(); for (int i=0; i<srcSize; i++) { di.next(); di.set(si.next()); } } } FYI: private static final int FILL_THRESHOLD = 25; private static final int COPY_THRESHOLD = 10;

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• At the Java DEMOgrounds - JavaFX

  - by Janice J. Heiss

  JavaFX has made rapid progress in the last year, as is evidenced by the wealth of demos on display. A few questions appear to be prominent in the minds of JavaFX enthusiasts. Here are some questions with answers provided by Oracle’s JavaFX team.When will the rest of the JavaFX code be available in open source?Oracle has started to open source JavaFX. The existing platform code will finish being committed to OpenJFX by the end of the year.Why should I use JavaFX instead of HTML5?We see JavaFX as complementary to HTML5, and most companies we talk to react positively once they understand how they can benefit from a hybrid solution. As most HTML5 developers will tell you, the biggest obstacle to deploying HTML5 applications is fragmentation. JavaFX offers a convenient way to render HTML and JavaScript within its WebView component, which provides the same level of quality and features across Windows, Mac, and Linux. Additionally, JavaScript in WebView can make calls into the Java code, and vice versa, allowing developers to tap into the best of both worlds.What is the market penetration of JavaFX? It is currently limited, as we've just made available JavaFX on Mac and Linux in August, but we expect JavaFX to be present on millions of desktop-type systems now that JavaFX is included as part of the JRE. We have also significantly lowered the level of effort required to deploy an application bundling the JRE and JavaFX runtime libraries. Finally, we are seeing a lot of interest by companies operating in the embedded market, who have found it hard to develop compelling UIs with existing technologies.Below are summaries of JavaFX Demos on display at JavaOne 2012:JavaFX EnsembleEnsemble is a collection of over 100 JavaFX samples packaged as a JavaFX application. This demo is especially useful to those new to JavaFX, or those not familiar with its latest features (e.g. canvas, color picker). Ensemble is the reference for getting familiar with JavaFX functionality. Each sample can be run from within Ensemble, and the API for each sample, as well as the source code are available alongside the sample.The samples source code can be saved as a NetBeans project for convenience purposes, or can be copied as is in any other Java IDE. The version of Ensemble shown is packaged as a native Windows application, including the JRE and JavaFX libraries. It was created with the JavaFX packager, which provides multiple packaging options, and frees developers from the cumbersome and error-prone process of packaging a Java application.FX Experience ToolsFX Experience Tools is a JavaFX application that provides different utilities to create new skins for your JavaFX applications. One of the most powerful features of JavaFX is the ability to skin applications via CSS. Since not all Java developers are familiar with CSS, these utilities are a great starting point to create custom skins. JavaFX allows developers to easily customize the look and feel of their applications through CSS. FX Experience Tools makes it easy to create new themes for JavaFX applications, even if you are not familiar with CSS. FX Experience Tools is a JavaFX application packaged as a native application including the JRE and JavaFX runtime libraries. FX Experience tools shows how this type of deployment simplifies the packaging of Java applications without requiring developers to master the intricacies of Java application packaging. The download site for FX Experience Tools is http://fxexperience.com/2012/03/announcing-fx-experience-tools/ JavaFX Scene BuilderJavaFX Scene Builder is a visual layout tool that lets users quickly design the UI of your JavaFX application, without coding. Users can drag and drop UI components, modify their properties, apply style sheets, and the FXML code they create for the layout is automatically generated in the background. The result is an FXML file that can then be combined with a Java project by binding the UI to the application’s logic. Developers can easily create user interfaces for their application, as well as separate the application’s UI from the application logic for easier maintenance. Attendees can get this app by going to javafx.com and checking the link at top of the “Overview” page.Scene Builder allows developers to easily layout JavaFX UI controls, charts, shapes, and containers, so that you can quickly prototype user interfaces. It generates FXML, an XML-based markup language that enables users to define an application’s user interface, separately from the application logic. Scene Builder can be used in combination with any Java IDE, but is more tightly integrated with NetBeans IDE. It is written as a JavaFX application, with native desktop integration on Windows and Mac OS X. It’s a perfect example of a JavaFX application packages as a native application.Scene Builder is available for your preferred development platform. Besides the GA release on Windows and Mac, a Developer Preview of Scene Builder for Linux has just been made available.Scenic ViewScenic View is a tool that can be used to understand the current state of your application UI, and to also easily manipulate properties of the scenegraph without having to keep editing your code. Creating UIs is a complex process, and it can be hard and tedious detecting these issues, editing the code, and then compiling it to test the app again. Scenic View is a great diagnostics tool that helps developers identify these issues and correct them at runtime.Attendees can get Scenic View by going to javafx.com, selecting the “Community” tab, and clicking the link under the “Third Party Tools and Utilities” section.Scenic View allows developers to easily examine the state of a JavaFX application scenegraph while the application is running. Some of the latest features added to Scenic View include event monitoring, javadoc browsing, and contextual menus. The download site for Scenic View is available here: http://fxexperience.com/scenic-view/ Conference TourConference Tour is an application that lets users discover some of the major Java conferences throughout the world. The Conference Tour application shows how simple it is to mix JavaFX and HTML5 into a single, interactive application. Attendees get Conference Tour here.JavaFX includes a Web engine based on Webkit that provides a consistent web interface to render HTML5 across operating systems, within a JavaFX application. JavaFX features a bi-directional bridge that allows Java APIs to call JavaScript within WebView, or allows JavaScript to make calls to Java APIs. This allows developers to leverage the best of both worlds.Java EE developers can take advantage of WebView and the JavaScript-Java bridge to allow their HTML clients to seamlessly bypass Web browser’s sandbox to access native system resources, providing a richer user experience.FXMediaPlayerFXMediaPlayer is an application that lets developers check different media functionality in JavaFX, such as synthesizer or support for HTTP Live Streaming (HLS). This demo shows how developers can embed video content in their Java applications. JavaFX leverages the underlying video (e.g., H.264) and audio (e.g., AAC) codecs on the user’s computer. JavaFX APIs allow developers to interact with the video content (e.g. play/pause, or programmable markers). Some of the latest media features introduced in JavaFX 2.2 include HTTP Live Streaming (HLS). Obviously there is a lot for JavaFX enthusiasts to chew on!

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• Finding the groups of a user in WLS with OPSS

  - by user12587121

  How to find the group memberships for a user from a web application running in Weblogic server ?  This is useful for building up the profile of the user for security purposes for example. WLS as a container offers an identity store service which applications can access to query and manage identities known to the container.  This article for example shows how to recover the groups of the current user, but how can we find the same information for an arbitrary user ? It is the Oracle Platform for Securtiy Services (OPSS) that looks after the identity store in WLS and so it is in the OPSS APIs that we can find the way to recover this information. This is explained in the following documents.  Starting from the FMW 11.1.1.5 book list, with the Security Overview document we can see how WLS uses OPSS: Proceeding to the more detailed Application Security document, we find this list of useful references for security in FMW. We can follow on into the User/Role API javadoc. The Application Security document explains how to ensure that the identity store is configured appropriately to allow the OPSS APIs to work.  We must verify that the jps-config.xml file where the application  is deployed has it's identity store configured--look for the following elements in that file: <serviceProvider type="IDENTITY_STORE" name="idstore.ldap.provider" class="oracle.security.jps.internal.idstore.ldap.LdapIdentityStoreProvider">             <description>LDAP-based IdentityStore Provider</description>  </serviceProvider> <serviceInstance name="idstore.ldap" provider="idstore.ldap.provider">             <property name="idstore.config.provider" value="oracle.security.jps.wls.internal.idstore.WlsLdapIdStoreConfigProvider"/>             <property name="CONNECTION_POOL_CLASS" value="oracle.security.idm.providers.stdldap.JNDIPool"/></serviceInstance> <serviceInstanceRef ref="idstore.ldap"/> The document contains a code sample for using the identity store here. Once we have the identity store reference we can recover the user's group memberships using the RoleManager interface:             RoleManager roleManager = idStore.getRoleManager();            SearchResponse grantedRoles = null;            try{                System.out.println("Retrieving granted WLS roles for user " + userPrincipal.getName());                grantedRoles = roleManager.getGrantedRoles(userPrincipal, false);                while( grantedRoles.hasNext()){                      Identity id = grantedRoles.next();                      System.out.println("  disp name=" + id.getDisplayName() +                                  " Name=" + id.getName() +                                  " Principal=" + id.getPrincipal() +                                  "Unique Name=" + id.getUniqueName());                     // Here, we must use WLSGroupImpl() to build the Principal otherwise                     // OES does not recognize it.                      retSubject.getPrincipals().add(new WLSGroupImpl(id.getPrincipal().getName()));                 }            }catch(Exception ex) {                System.out.println("Error getting roles for user " + ex.getMessage());                ex.printStackTrace();            }        }catch(Exception ex) {            System.out.println("OESGateway: Got exception instantiating idstore reference");        } This small JDeveloper project has a simple servlet that executes a request for the user weblogic's roles on executing a get on the default URL.  The full code to recover a user's goups is in the getSubjectWithRoles() method in the project.

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• Managing highly repetitive code and documentation in Java

  - by polygenelubricants

  Highly repetitive code is generally a bad thing, and there are design patterns that can help minimize this. However, sometimes it's simply inevitable due to the constraints of the language itself. Take the following example from java.util.Arrays: /** * Assigns the specified long value to each element of the specified * range of the specified array of longs. The range to be filled * extends from index <tt>fromIndex</tt>, inclusive, to index * <tt>toIndex</tt>, exclusive. (If <tt>fromIndex==toIndex</tt>, the * range to be filled is empty.) * * @param a the array to be filled * @param fromIndex the index of the first element (inclusive) to be * filled with the specified value * @param toIndex the index of the last element (exclusive) to be * filled with the specified value * @param val the value to be stored in all elements of the array * @throws IllegalArgumentException if <tt>fromIndex &gt; toIndex</tt> * @throws ArrayIndexOutOfBoundsException if <tt>fromIndex &lt; 0</tt> or * <tt>toIndex &gt; a.length</tt> */ public static void fill(long[] a, int fromIndex, int toIndex, long val) { rangeCheck(a.length, fromIndex, toIndex); for (int i=fromIndex; i<toIndex; i++) a[i] = val; } The above snippet appears in the source code 8 times, with very little variation in the documentation/method signature but exactly the same method body, one for each of the root array types int[], short[], char[], byte[], boolean[], double[], float[], and Object[]. I believe that unless one resorts to reflection (which is an entirely different subject in itself), this repetition is inevitable. I understand that as a utility class, such high concentration of repetitive Java code is highly atypical, but even with the best practice, repetition does happen! Refactoring doesn't always work because it's not always possible (the obvious case is when the repetition is in the documentation). Obviously maintaining this source code is a nightmare. A slight typo in the documentation, or a minor bug in the implementation, is multiplied by however many repetitions was made. In fact, the best example happens to involve this exact class: Google Research Blog - Extra, Extra - Read All About It: Nearly All Binary Searches and Mergesorts are Broken (by Joshua Bloch, Software Engineer) The bug is a surprisingly subtle one, occurring in what many thought to be just a simple and straightforward algorithm. // int mid =(low + high) / 2; // the bug int mid = (low + high) >>> 1; // the fix The above line appears 11 times in the source code! So my questions are: How are these kinds of repetitive Java code/documentation handled in practice? How are they developed, maintained, and tested? Do you start with "the original", and make it as mature as possible, and then copy and paste as necessary and hope you didn't make a mistake? And if you did make a mistake in the original, then just fix it everywhere, unless you're comfortable with deleting the copies and repeating the whole replication process? And you apply this same process for the testing code as well? Would Java benefit from some sort of limited-use source code preprocessing for this kind of thing? Perhaps Sun has their own preprocessor to help write, maintain, document and test these kind of repetitive library code? A comment requested another example, so I pulled this one from Google Collections: com.google.common.base.Predicates lines 276-310 (AndPredicate) vs lines 312-346 (OrPredicate). The source for these two classes are identical, except for: AndPredicate vs OrPredicate (each appears 5 times in its class) "And(" vs Or(" (in the respective toString() methods) #and vs #or (in the @see Javadoc comments) true vs false (in apply; ! can be rewritten out of the expression) -1 /* all bits on */ vs 0 /* all bits off */ in hashCode() &= vs |= in hashCode()

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• How to use apache beanutils in a NetBeans platform project? (Error with commons-logging)

  - by I82Much

  For starters, this question is not so much about programming in the NetBeans IDE as developing a NetBeans project (e.g. using the NetBeans Platform framework). I am attempting to use the BeanUtils library to introspect my domain models and provide the properties to display in a property sheet. Sample code: public class MyNode extends AbstractNode implements PropertyChangeListener { private static final PropertyUtilsBean bean = new PropertyUtilsBean(); // snip protected Sheet createSheet() { Sheet sheet = Sheet.createDefault(); Sheet.Set set = Sheet.createPropertiesSet(); APIObject obj = getLookup().lookup (APIObject.class); PropertyDescriptor[] descriptors = bean.getPropertyDescriptors(obj); for (PropertyDescriptor d : descriptors) { Method readMethod = d.getReadMethod(); Method writeMethod = d.getWriteMethod(); Class valueType = d.getClass(); Property p = new PropertySupport.Reflection(obj, valueType, readMethod, writeMethod); set.put(p); } sheet.put(set); return sheet; } I have created a wrapper module around commons-beanutils-1.8.3.jar, and added a dependency on the module in my module containing the above code. Everything compiles fine. When I attempt to run the program and open the property sheet view (i.e.. the above code actually gets run), I get the following error: java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at java.lang.ClassLoader.loadClass(ClassLoader.java:319) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:330) at java.lang.ClassLoader.loadClass(ClassLoader.java:254) at org.netbeans.ProxyClassLoader.loadClass(ProxyClassLoader.java:259) Caused: java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory starting from ModuleCL@64e48e45[org.apache.commons.beanutils] with possible defining loaders [ModuleCL@75da931b[org.netbeans.libs.commons_logging]] and declared parents [] at org.netbeans.ProxyClassLoader.loadClass(ProxyClassLoader.java:261) at java.lang.ClassLoader.loadClass(ClassLoader.java:254) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:399) Caused: java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory at org.apache.commons.beanutils.PropertyUtilsBean.<init>(PropertyUtilsBean.java:132) at org.myorg.myeditor.MyNode.<clinit>(MyNode.java:35) at org.myorg.myeditor.MyEditor.<init>(MyEditor.java:33) at org.myorg.myeditor.OpenEditorAction.actionPerformed(OpenEditorAction.java:13) at org.openide.awt.AlwaysEnabledAction$1.run(AlwaysEnabledAction.java:139) at org.netbeans.modules.openide.util.ActionsBridge.implPerformAction(ActionsBridge.java:83) at org.netbeans.modules.openide.util.ActionsBridge.doPerformAction(ActionsBridge.java:67) at org.openide.awt.AlwaysEnabledAction.actionPerformed(AlwaysEnabledAction.java:142) at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2028) at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2351) at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387) at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242) at javax.swing.AbstractButton.doClick(AbstractButton.java:389) at com.apple.laf.ScreenMenuItem.actionPerformed(ScreenMenuItem.java:95) at java.awt.MenuItem.processActionEvent(MenuItem.java:627) at java.awt.MenuItem.processEvent(MenuItem.java:586) at java.awt.MenuComponent.dispatchEventImpl(MenuComponent.java:317) at java.awt.MenuComponent.dispatchEvent(MenuComponent.java:305) [catch] at java.awt.EventQueue.dispatchEvent(EventQueue.java:638) at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:125) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188) at java.awt.EventDispatchThread.run(EventDispatchThread.java:122) I understand that beanutils is using the commons-logging component (wish it mentioned that in the javadoc, but that's OK). I have tried adding the commons-logging component in two different ways (creating a wrapper library around the commons-logging library, and putting a dependency on the Commons Logging Integration library). Neither solves the problem. Has anyone successfully used BeanUtils in a NetBeans Platform project?

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