JavaPolis: More About ME

Thursday’s JavaPolis keynote starts with Bruce Eckel doing basically a partner slot — a 45 minute promotion speech for Flex (what else). What’s this doing at a Java conference? How much did Adobe pay for….. — Oh. Okay. I just saw the first demo. I want to use this! Show me more! And it works in everything with a Flash player on it? Where can I sign up?

Stephan Janssen’s keynote on his side project,, (no seriously, there’s some great stuff on there and the new (Flex) version looks very slick), gives me some time to recap the last two sessions I saw yesterday. As planned, I chose the EJB 3.1 session over yet another intro into JRuby on Rails. While EJB 3.1 promises some useful new features (WAR packaging, singleton beans, timer service etc), a whole hour is a lot of time to listen to the ins and outs of features and subfeatures.

Then came the moment we’d all been waiting for: a panel discussion with James Gosling, Joshua Bloch, Neal Gafter and Martin Odersky about the future of computing. Literally the future of computing, where most of us had expected or hoped to see a discussion about the future of Java. So what did I learn from this?

  1. Interviewing is a real profession. A panel like this needs a good host who will ask the right questions, ask follow-through questions that are on everyone’s minds, and most of all, can keep the discussion going. Uncomfortable moments of silence at a table with guests like these, with about 2000 people watching, just shouldn’t happen.
  2. “Closures are sexy.” Guess who said that, completely out of the blue? But more importantly, why didn’t the interviewer touch the subject that everyone expected to guarantee some fierceful debate?
  3. a < b is not the same as a – b < 0. In C. I think that’s even a better t-shirt text than “There’s only 10 kinds of people: those who understand binary arithmatic and those who don’t.”

The Keynote Continues

Sun’s Tim Cramer is next on Thursday’s keynote. “Who’s programming Java ME?” he asks the audience. About five people raise their hands. “Who’s done it with NetBeans?” One hand remains in the air.

This shows my doubts about the ever-recurring Sun demos (usually during keynotes) with SunSpots, robots and phones. Fun stuff, but how many of us are actually using it? Most of us are developing web apps — which is not to say that there shouldn’t be attention for anything beyond that, but this is overdoing it.

One last observation: while I’m in deep concentration for writing this blog post, I suddenly hear Sun’s Java evangelista Angela Caicedo talk about “moving my guys around.” Huh? Oh, she’s talking about sprites.

2007-12-13. No responses.

“Please Neal,” Pleads Gosling

Bob Lee’s session on Guice got mixed reviews. Having already seen his introduction to Guice, I had an pretty good idea of what Guice is, so I enjoyed hearing about his 50 or so best practices and previews of things to come. However, I spoke with another visitor afterwards who was less impressed; he had expected more of an introductory session.
Right now I’m in a GWT session where one of the speakers has been delayed and time is being killed by someone demoing GWT applications somewhere on the Internet, followed by another substitute who starts his presentation with the announcement “Let’s see how fast we can go through this stack of slides.” and welcomes every slide with a half-surprised “Okay…” — has he even seen these slides before?
To start the day off, there was a triple keynote: Stephan Janssen, building up via Bruce Eckel to James Gosling himself. Something that caught my attention on one of his slides: Java would enable you to “Learn Once, Work Anywhere”. Is that really true? Even in the Java EE world I’m in, developers are getting more and more specialized, making a switch non-trivial — let alone the gap that exists between business application and real-time development. Yes, the language may be the same, but different libraries, frameworks, and even the entire context within which you’re working may well require you to virtually start afresh, if you’re thinking about switching.
There was of course some obligatory promoting of NetBeans 6 and Java FX; a short and not very impressive demo with Sunspots and robots (read the book, seen the movie — again!); and a plea to Neal Gafter to get closures into Java 7. Which is kind of weird if you think about it: the “father of Java” asking a Googler to please implement the feature the he himself was unable to include in Java in the first place.

Simon Ritter doing a robot demo

Near the end, I saw a JasperSoft employee losing about 5 litres of sweat: his guest appearance in Gosling’s session went sour when the beamer, switched over to his laptop, remained black for an uncomfortable number of minutes. The gum he was chewing did not help his demo either, by the way.
The GWT session did not end well. Both guest presenters battling for attention, both ignoring any comments one makes about the other’s slides; as well as the text on half of the slides being garbled and unreadable… Fortunately GWT looks slick enough (both code and end result) but definitely needs better promotors.

2007-12-12. 4 responses.

Warming Up For JavaPolis


2007-12-12. No responses.

A Late Arrival

This plan was doomed from the start: leave from work at 4PM and try to reach Antwerp within two hours, so I could collect my badge and goody bag tonight instead of tomorrow morning (together with 2000 fellow JavaPolis visitors). It was worth a try, but I should have known you can’t beat the Dutch rush hour at its peek. Exactly one hour late (an hour spent halfway through in a traffic jam caused by people looking at an accident on the other side of the road) I entered the Metropolis building–only to be disappointed by Stephan himself. So that’s one beer less to drink tonight, in an attempt to go to bed early and be on time tomorrow morning.
Anyway, all will be forgotten when I sit down tomorrow for the first keynote–and after that for all those sessions I’m looking forward to: Gosling, Gafter, Bloch… Sessions about EJB3.1 and Guice and Scala… (Of course, since I didn’t get the goody bag with the program yet, I’m listing all these from memory so I’ve probably forgotten one or two). I’m sorry to say I will probably miss the JRuby session with Ola Bini and Charles Nutter: you can only see so many introductions into Ruby and Rails.
And in the meantime I’ve done a little reconnaissance in Antwerp’s town center after checking into the hotel. As always, the city is great fun to be in Christmas time: nicely decorated and full of life (and beer). I had some Belgian fries at Frituur No 1 and walked around town a little. I nearly bumped into someone looking a lot like James Gosling, taking snapshots of the Antwerp cathedral. Perhaps not the right moment to ask for an autograph…


On the road to Antwerp…

2007-12-11. No responses.

JavaPolis Going Nuclear

Just when I was about to drive off to Antwerp for this year’s JavaPolis, I learned that a fire has started in Antwerp’s nuclear plant ‘Doel’. Apparently the fire is located in a side building and there’s no immediate danger to the public. Which is exactly what I would say to prevent complete chaos from breaking out…

2007-12-11. No responses.

Where To Marry In Paris (Part 3)

(This is part 3 of 3; part 1 is here, part 2 is here)

We returned from Paris late Sunday evening (March 25th).

What remained was images, shreds of memories, and many of them, in spite of the short time we were there:

The Nautilus-like decoration of the Arts & Métiers subway station.

The American girl in the brasserie too close to the Eiffel tower (but we were too tired to go any further), shouting, “Sir, you’re from Philly, sir?” at an unsuspecting Frenchman wearing an Eagles cap.

The closed doors of the Fashion museum that we had wanted to visit after the Eiffel tower and lunch; apparently, the museum is now closed for visits altogether. We were lured to it by an entry in the Lonely Planet guide, promising “some 100,000 outfits and accessories from the 18th century to the present day”. Instead, we kept walking along the Seine to the Museum of Discovery (Palais de la Découverte), hoping to find traces there of the turn of the 19th century world exhibition that took place there in 1937. However, besides the building itself, very little reminded of that historic fact. The museum houses several themed exhibitions, some very entertaining (animals, visual tricks), some extremely boring. In the animal exhibition, a little rat was showing how it had been trained to run around in a maze and get a tasty snack at certain intervals. Somehow, that reminded me of our own wanderings across Paris.
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2007-05-11. 2 responses.

Where To Marry In Paris (part 2)

(This is part 2 of 3; part 1 is here, part 3 is here)

There’s a lot in Paris to be seen besides museums. Unfortunately, most of these things are outdoors and can best be visited with a bit of sunshine and a pleasant spring temperature. As we had neither of these on our short trip, we had to spend a lot more time inside the shops on the boulevard des Champs Elysées than we normally would have. We had to admire the view of the Eiffel tower from underneath it. And we had to extrapolate what it’s like to spend a day in the park from sitting on a bench in the tuileries for 10 minutes in the only rays of sunlight that we did get.

There is however another very important indoors activity to be done in Paris, as in every part of France: eating! At lunchtime, heavy rains were usually poring down on us, making it impossible to sit down in a park with nothing more than a baguette and some Coulommiers or other cheese. At dinnertime, we were forced to eat out as we stayed in a hotel room, so we really were unable to do some shopping at a nice Parisian market and have a go at the local ingredients ourselves. In short, we couldn’t help but eat out twice a day; and as we felt obliged to do as the Parisians do, we just had to eat a hot meal twice a day as well. What a punishment…
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2007-04-01. One response.

Where To Marry In Paris (part 1)

Even though Paris is only a 6 hour drive from where we live, we never actually go to the trouble of finding a hotel and driving up there. Until now. It’s been 27 years since I last spent some time in Paris–more time than the average hour it takes to drive through it when we’re on our way to the south of France. 27 years, that’s more than anybody should have to wait to return to Paris. So we finally found a decent hotel (see map below: marker A) and arrived after a smooth enough ride through the streets of Paris (thanks to Eva, who for some reason wanted us to take a scenic route off the highroad when we entered France, but thankfully got herself back on track as soon as we reached the city).

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2007-04-01. 3 responses.

Java Closure Examples

One thing I miss in the current BGGA proposal for closures in Java 7, is a good set of examples. There are some examples, but they don’t cover most situations. Also I feel that more examples might better show the advantages of having closures in Java. Of course, as long as the Java compiler has not been patched to work with closures, this remains “swimming on dry land” (as we say in Holland). Syntax errors will no doubt be abundant, and everything might change with the next version of the proposal. I hope this will still be useful to people wondering why there should be closures in Java in the first place. This is why: it makes your code cleaner and leaner.

So here goes, starting with some simple examples. Each example consists of the closure method usage (which will probably be used most) and the closure method definition (which will mostly be done by library developers).

Select objects from collection

This is an example of how the CollectionUtils utility methods could be rewritten using closures.

public Collection<Book> getPublishedBooks(Collection<Book> books) {
    return select(books, {Book book =>

 * Returns the T objects from the source collection for which the
 * given predicate returns true.
 * @param source
 *            a collection of T objects, not null
 * @param predicate
 *            returns true for a given T object that should be
 *            included in the result collection
 * @return a collection of T objects for which the predicate
 *         returns true
public static <T> Collection<T> select(Collection<T> source,
        {T=>Boolean} predicate) {
    Collection<T> result = new ArrayList<T>();
    for (T o : source) {
        if (predicate.invoke(o)) {
    return result;

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2007-02-05. 17 responses.

Test Your Ruby Skills On

JavaBlackBelt is a fast growing community whose members take tests to assess their skills in various Java-related topics. The tests themselves are created also by the site’s members. A small number of Ruby enthusiasts is currently working to add a Ruby exam to this Java-oriented site. I interviewed Mr. John Rizzo, one of JavaBlackBelt’s founders, and asked him what JavaBlackBelt has to offer Java and Ruby developers.

Danny: Why do we need JavaBlackBelt if we already have Sun’s Java certificates?

John Rizzo, co-founder of JavaBlackBeltJohn: We felt that, in the real world, with real teams and real projects, we have no way to assess, in an objective way, Java developers. Java requires so many things to learn. Sun is responsible for many Java apis, like JMS, Java2D, Swing, JDBC, servlet, EJB and so on. But their exam covers only a very small part of that. For example, the Sun Certified Java Programmer (SCJP) is a coverage of a small part of Java SE; JDBC, simple database access, is not even in it. And there are so many other tools and apis that are covered by other groups: Jakarta, Eclipse, jBoss. Their core business is developing their framework, not doing certifications. So there is nothing for this. If you see what a Java developer has to learn the first six months, or the first one or two years, to be productive in a project… All these technologies, and certification covers a very small part, maybe less than 10%. This is the first reason.

The other reason is that when you have three years of experience as a Java developer, and you’d like to do the first Sun certification (SCJP), you still need to study for a few days before you can take the test. Is that normal? You are an experienced developer, and you need to study, before Sun recognizes your skills. That’s why the exams on JavaBlackBelt are made keeping in mind that the candidates have all the resources available. Books, Eclipse, Google, whatever. They can search the web, search the Java apis, they can try things out in Eclipse. They’re only limited by time. They don’t have to remember things by heart. But the exams are hard, even with that. It depends on the exams, we also have basic exams, to help the beginners and to encourage the beginner to learn. Like Ruby Basic for example. And then we have more advanced exams; not just one big certification with a lot of questions.
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2007-01-29. No responses.

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