Adam Kruszewski :: WebLog();

Just view first few minutes of Soble's interview with Jonathan Schwartz. Pretty cool!

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I have this on my Things To Do In Some Distant Future^TM list but today I have spotted one person who actually was looking for such article -- so I have finally wrote a small how-to develop Netbeans modules within Eclipse IDE.

To provide a custom component docked into statusbar of NetBeans platform/IDE ( actually I'm using it only as a platform :>) ) just create class implementing org.openide.awt.StatusLineElementProvider. It is a simple one-method interface:

public abstract interface StatusLineElementProvider {
  
  public abstract Component getStatusLineElement();
}

For a while I was playing with J2SE5.0 APT tool (Brian Oxley have written how to create annotation processor for APT) -- this tool mimics behaviour of javac adding additional annotation processing abilities. I was wondering how could I run it to allow multiple passes of different annotation processors (with few ant tasks launched sequentially or something like that), but in mean time I have found JAM. It is Annogen component and it abstracts JSR175 and XDoclet annotations and provide single layer for processing them in a easy way:

  public static void main (String[] args ) throws IOException {

    JamServiceFactory factory = JamServiceFactory.getInstance ();
    JamServiceParams params = factory.createServiceParams ();

    // search in source files.
    params.includeSourcePattern (new File[] { new File (
        "src/sandbox/jam/test/" ) }, "*.java" );

    JamService service = factory.createService (params );

    JamClassIterator jClassIter = service.getClasses ();
    while (jClassIter.hasNext ()) {
      JClass elem = (JClass ) jClassIter.next ();
      System.out.println ("Class name:" + elem.getSimpleName ());
      JAnnotation[] annotations = elem.getAnnotations ();
      dumpAnnotations (annotations );

      for (JField field : elem.getFields ()) {
        System.out.println (" f> " + field.getSimpleName () + ":"
            + field.getType ().getSimpleName ());
        annotations = field.getAnnotations ();
        dumpAnnotations (annotations );
      }

      for (JMethod method : elem.getMethods ()) {
        System.out.println (" m> " + method.getSimpleName ());
        annotations = method.getAnnotations ();
        dumpAnnotations (annotations );
      }
    }
  }

  private static void dumpAnnotations (JAnnotation[] annotations ) {
    for (JAnnotation ann : annotations ) {
      System.out.println ("    a> " + ann.getSimpleName ());
      for (JAnnotationValue annVal : ann.getValues ()) {
        System.out.println ("       v> " + annVal.getName () + ":"
            + annVal.asString ());
      }
    }
  }

Above code with simple annotated class can be downloaded here as Eclipse compressed project (just import it into workspace; Eclipse 3.1M4 is required and you'll need to fix path for tools.jar pointing to your JDK's copy).

jCoverage/djUnit users should check Cobertura project on SourceForge. Basically it is "just a fork" but it seems it'll be more actively developed than original jcoverage.

We all know this principle and we all know how hard is code defensively to keep it.
But it is a little easier now Today AJDT team released developement version 2005012444759 of their Eclipse plugin, providing latest AspectJ5 capabilities to compile and wave J2SE 5.0 code with support to pointcuts matching annotated elements (there is no parameter and package annotations support right now).
Using annotations and one simple aspect we can check all calls to chosen methods and throw IllegalArgumentsExceptions whenever null value is passed to them. Here is how to do it:

• First, create marker kind annotation (let's name it a "GoodCitizen") which we would use to mark methods which calls should be "null parameter" free.
  

  package sandbox.nullchecks;
  
  import java.lang.annotation.*;
  
  /**
   * Indicates methods which should behave as "Good Citizen".
   * In conjunction with GoodCitizenAspect all such methods
   * should throw IllegalArgumentException when there is 
   * null value passed to them or they return null value. 
   */
  @Retention(RetentionPolicy.CLASS)
  @Target( {ElementType.METHOD} )
  @Documented
  public @interface GoodCitizen {
  
  }
  

• Then create aspect which will do the hard work:
  

  package sandbox.nullchecks;
  
  public aspect GoodCitizenAspect {
    
    // it will match any method call to annotated method with any
    // signature.
    pointcut goodCitizenMethodCall() : 
       call (@sandbox.nullchecks.GoodCitizen * *(..));
  
    before() : goodCitizenMethodCall() {
      Object[] methodArgs = thisJoinPoint.getArgs();
      for (int t = 0; t < methodArgs.length; t++) {
        if ( null == methodArgs[t] ) {
          throw (new IllegalArgumentException("Parameter " + (t + 1)
              + " of " + methodArgs.length + " in call to "
              + thisJoinPoint.getSignature()
              + " was NULL, but method is annotated as GoodCitizen."));
        }
      }
    }
  }
  

• Now just try it!
  

  package sandbox.nullchecks;
  
  
  public class GoodCitizenExample1 {
  
    @GoodCitizen
    public void citizenTest(String str, int prim, Object obj) {
      System.out.println(str+":"+prim+":"+obj);
    }
    
    public static void main(String[] args) {
      GoodCitizenExample1 ex = new GoodCitizenExample1();
      // it should yell about null as third parameter when executed.
      ex.citizenTest("str", 9, null);
    }
  }
  

Exception in thread "main" java.lang.IllegalArgumentException:
 Parameter 3 of 3 in call to 
 void sandbox.nullchecks.GoodCitizenExample1.citizenTest(String,
 int, Object) was NULL, but method is annotated as GoodCitizen.

  at sandbox.nullchecks.aspects.GoodCitizenAspect.ajc$before
 $sandbox_nullchecks_aspects_GoodCitizenAspect$1$38402fab
   (GoodCitizenAspect.aj:23)
  at sandbox.nullchecks.GoodCitizenExample1.main
   (GoodCitizenExample1.java:13)

  pointcut NonVoidGoodCitizenMethodCall() : goodCitizenMethodCall() 
    && call(!void *(..));

  after () returning(Object retValue) : NonVoidGoodCitizenMethodCall() {
    if (null == retValue) {
      throw (new IllegalArgumentException("Method "
        + thisJoinPoint.getSignature()
        + " returned NULL but it is marked as GoodCitizen."));
     }
  }

If you use Swing in your applications then make sure to check out Romain Guy's Weblog. He has very useful tips for Swing users. My personall favourite is "wait with style" (just check this webstartable demo). I hope He will create a full WaveLaF someday because it LooksSoCool(tm)

As far as I know there is no simple way to use PicoContainer (tiny IoC framework) in servlet container environment for filters, servlets and so on... (this is also true for any managed object in non-IoC aware container)

The problem is that we cannot control instantiation of such objects -- it is hard coded into servlet engine. But we can of course execute dependecy lookup code in contructor itself (loosing any IoC abilities :/), or we can use AspectJ (or any other AOP framework) to decouple dependency lookup code from constructor. going futher we can use setter injection on our already instantiated object.

It sounds simple and (probably) logical but PicoContainer desn't support injection in already instantiated object 'out of the box' (or at last I couldn't find it). I have achieved this by hacking around SetterInjectionComponentAdapter and creating my own InstanceSetterInjectionAdapter. Resolving dependencies is now as easy as creating one simple aspect:

  pointcut ReferenceServiceInitialization () : execution (public ReferenceService.new ());
 
  after (): ReferenceServiceInitialization () {
    MutablePicoContainer picoContainer = getPicoContainer ();
    PicoUtils.resolveDependencies (picoContainer, thisJoinPoint.getThis ());
  }

   @injectDeps (container="root") public class SomeFilter implements ServletFilter {
    ...
   }

An example is available as compressed eclipse project, just import it into your workspace and take a look. It doesn't depend on servlet/or-something container it is just uses this IoC hack to show this basic idea. (you must have AJDT installed because it is AspectJ project)

Probably You have heard this a while before but just for reference: Here you can download Sun Studio Creator 2 if you are a Sun Developers Network member (registration is free AFAIR).
Personally I just wonder if they fixed the unability to compile with "-source 1.5" which was a major PITA in EA1/EA2 releases? (still downloading on my 256/128kbps adsl connection).

If you doesn't know it already here it is: Hibernate 3.0 Tools for Eclipse and it looks very promising! It is designed for Eclipse 3.1M4 and the download is approx. 8Mb.

There are: JDeveloper 10g (free of charge for all developers), Eclipse 3.1, preview version of Exadel Studio 3.0 and final version of jsr 181 (metadata for web services).

And all in one day, huh! :-)

From thursday I'm lying in bed feeling very sick so I have time to play with latest snapshots of maven2, its plugins and eclipse plugin for it. So far I can tell that I'm impressed, just invoking mvn clean install deploy:deploy and viola! Everything is simple and almost works. I ran upon some difficulties at the beginning:

• MavenIde for Eclipse didn't show precise error messages from default maven compiler, eg. like it doesn't like generics when not set to 1.5 source compatibility (but aspectj compiler plugin does).
• it also somewhat fails to integrate nicely with latest WTP releases -- maven dependencies aren't copied to .deployment/app/WEB-/INF/lib/ directory upon build.
• Aspectj and cobertura plugins are accessible from mojo sandbox subversion repository but as source code and I didn't find a way for maven to auto download them (other than deploying them to my own private repository).

For all jython users (if you didn't already know it) -- there is a nice interactive console avaliable (with autocompletion and command history). You can get it from http://dev.artenum.com/projects/jyconsole.
It would be nice to have similar functionality included in pyDev Eclipse plugin :-)

Today I have stumbled upon a blog post titled "… And what about SealedObject and GuardedObject?" and as a quick exercise I have implemented spoken feature in AspectJ. I didn't write an annotation processor because it was quicker (for me) to go with AspectJ and besides APT builder for Eclipse 3.1.2 is not working for me at the moment. So I'm leaving implementation of a real AnnotationProcessor to orginal author of the idea.
You can try it for yourself by downloading archived project [12kb], and importing it to your workspace. To build it you'll need Eclipse 3.1 and AJDT plugin.

When looking for a game for New Year's Day (see last post ;-))
I stumbled on continuation of RoboCode -- RoboCodeNG.
The first thought I got when I first saw robot team API was: "Wow! How much neater could computer science laboratories be if we could implement byzantene agreement solutions in RoboCode instead of PVM!" ;-)

Some details about this game: It is Java based, you write robot code in pure Java ( you can use Eclipse/NetBeans/IDEA/... for it ) and it is somewhat similar to corewars -- you have an arena where robots makes fights. As very nice addition you can have teams of robots cooperating with each other.

In last week eclipse team released version 3.1M4 of their IDE which (almost) fully supports new J2SE 5.0 features. There was also release of Eclipse WebTools Milestone 2 which of course works with Eclipse 3.1M4 :-) (there is also a small tutorial available)

I highly recommends playing with those -- annotations, generics, enums and others are just addictive :-> (I just can't wait for AJDT J2SE5.0 support; annotations and AOP are IMHO just a killer combination for medium/large projects)

One small tip for WebTools -- don't use spaces in your application server name; and if you share a project with others make sure they have configured J2EE runtime libraries with the same name. (or they will see a nice NPE after importing that project into workspace).