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Codesnippet Doclet 0.20 Release - 2017-02-16 10:40:00

Enhance your Javadoc with Codesnippet4Javadoc version 0.20 which now supports special "coloring" for strings and comments.

--JaroslavTulach 10:40, 16 February 2017 (UTC)

Beware of DefaultMethods - 2016-09-24 10:42:00

DefaultMethods is a new feature of JDK8 that we many cried for. Yet, they carry certain drawbacks with themselves. For example one can write a valid Java program that compiles and works on JDK7, but is broken on JDK8!

--JaroslavTulach 10:42, 24 September 2016 (UTC)

Swing's Bad Reputation - 2016-08-26 10:37:00

Is Swing's openness reason for its so bad reputation?

--JaroslavTulach 10:37, 26 August 2016 (UTC)

Become Polyglot by Learning Java! - 2016-07-22 05:33:00

I was invited to give a talk at CurryOn 2016 about Truffle called Become Polyglot by Learning Java!. It provoked tweets like: If you only watch one talk from @curry_on_conf, this one from @JaroslavTulach on Graal/Truffle is stunning. Here is its recording:

Or go to YouTube page.

--JaroslavTulach 05:33, 22 July 2016 (UTC)

Pitfalls of APIReviews - 2016-07-17 13:38:00

There are two pitfalls of an APIReview. Either there is no code to review or there is too much code already written. The too little code case can easily be fixed. As Linus Torwalds use to say: Talk is cheap. Show me the code!

However what to do when APIReview brings in complex, complete solution with code almost ready for integration? Isn't that insulting? What kind of review one is supposed to perform then? Claim that the solution is completely wrong? That won't make the author happy. On the other hand coming for an architecture advice with fully working version isn't polite to reviewers either. Shall we read it as: Look how great I am! Approve the APIReview now!

Maybe there is a way to handle such review as well. But it remains to be seen if it works. Wish me luck.

--JaroslavTulach 13:38, 17 July 2016 (UTC)

Test your APIs Easily with Maven SigTest Plugin - 2016-07-15 17:52:00

The NetBeans API & Maven community (e.g. me and Miloš Kleint) is proud to announce the immediate availability of sigtest-maven-plugin. Signature testing has never been easier: just follow the tips on the SigTest main page and you'll never make an incompatible change since then!

Read TheAPIBook and let NetBeans SigTest Maven plugin look over you and make you great API designer! Enjoy!

--JaroslavTulach 17:52, 15 July 2016 (UTC)

Make Your Builder Whine! - 2016-06-26 20:00:00

Another variation on the topic of builder patterns. A builder that can track N essential attributes and whine (by throwing a checked exception) until all of them are specified.

Learn how to make your builder whine!

--JaroslavTulach 20:00, 26 June 2016 (UTC)

Chameleon Builder: Changes its Return Color! - 2016-06-16 09:34:00

Hear the news! A new creature of the API design patterns rare species has been discovered. It looks like a builder pattern, but it ducks like something else. If you take a closer look you'll find out it is a chameleon! It changes its return type depending on its state.

Do you want to protect your own builder like a chameleon? Follow this link and learn the trick!

Once you discover the beauty, you'll not stop until you get your own chameleon builder into your own design!

--JaroslavTulach 09:34, 16 June 2016 (UTC)

Builder to Tame Your Checked exception! - 2016-06-13 08:00:00

Here is a nice extension to the builder pattern that allows one to control whether the final build() method throws a Checked IOException or not.

Enjoy this new addition to the list of APIDesignPatterns.

--JaroslavTulach 08:00, 13 June 2016 (UTC)

Boost Your Career: Become an API Tester! - 2016-06-06 08:13:00

Motto: the easiest way to learn something about a code base is to fix bugs. The easiest way to learn something about design API is to join an APIUsabilityStudy!

There are many reasons why you should care about the Truffle framework (please check the changelog of just released version 0.14 to learn more), but the most important one is related to API Design and your career:

I need API testers! I need to organize a usability study of the Truffle API and I need developers to perform it. How can you help?

We have prepared five easy tasks: use Truffle to invoke a code in Ruby, JavaScript, R, exchange data between Java and one of those languages using Truffle interop, etc. In addition to that we ask you five questions: What did you like/dislike? What should we improve, etc.? Overall, the whole study should be easy and entertaining. You can learn something new (e.g. Truffle) and even earn some money.

Originally I wanted to repeat the previous success of netbeans:Html4JavaUXStudy2014, but the then used service is no longer available due to small demand. Understandable, but a shame! I know the demand for API related courses is low (I do one once a few years), but it is always very valuable to seek an advice when it comes to API - the on-line API usability study was really great idea! Alas, we need to organize it ourselves.

Are you interested to help us? If your want to be an API tester for a few hours, please write to my email practical@apidesign.org and I share more details. Thanks in advance!

--JaroslavTulach 08:13, 6 June 2016 (UTC)

Uncheck Your Checked exception! - 2016-04-06 16:26:00

Checked exceptions are Java invention and many like to argue that they are the worst invention ever. I like exceptions and I like Checked exceptions. Today I am ready to explain why!

Do you believe people should only use runtime exceptions? That checked exception add too much overhead? Then you are wrong!

I agree that the concept of checked exceptions in Java has some drawbacks, but I am ready to explain how to overcome the restrictions and uncheck your checked exception whenever you want. Enjoy!

--JaroslavTulach 16:26, 6 April 2016 (UTC)

Improve Javadoc of Your API: Stop showing crappy code samples! - 2015-12-30 15:59:00

I've just finished integration of Codesnippet Javadoc Doclet into Truffle API and the result is great: we found out that one of the samples (actually the first one that I tried) was not compilable!

If you care about Javadoc of your API, consider using Codesnippet doclet too!

Btw. it surprises me I am the first one who created something like this! Showing snippets in documentation is so common. But maybe it is the same issue as with TheAPIBook - it was the first book that ensured all the code samples are compilable by extracting them from real source code (using similar infrastructure as Codesnippet doclet provides). And it worked - while Errata of every book is full of comments about incorrect code samples, there is none for TheAPIBook.

Do your API a favor: use Codesnippet Javadoc Doclet and make your code samples real!

--JaroslavTulach 15:59, 30 December 2015 (UTC)

Introducing Sigtest into Your Project Workflow! - 2015-11-23 10:34:00

Truffle project is using Sigtest since today. I am maintaining the Truffle APIs since May, 2015 and I was applying my best knowledge and skills to design it properly. However I have to admit, I was operating in a blindness. Without having tests it is hard to decide whether your code change doesn't break your product. When designing API, it is important to know whether a change is or isn't backward compatible. Without a tool like Sigtest, it is almost impossible to do that manually!

Every project that designs an API needs an automated compatibility check. Learn what it takes to introduce such checks into your project by reading about the TruffleSigtest showcase!

--JaroslavTulach 10:34, 23 November 2015 (UTC)

Enforcing Proper API Usage by Law - 2015-06-15 09:21:00

Enforcing proper usage of an API is hard. One needs to strive for clarity, one can invent engineering solutions to the problem, but at the end clever hacker always find a way around it. But there is a cure: Let's choose our licenses wisely and scare the hackers with legal actions!

At the end it could also solve the famous sun.misc.Unsafe issue...

--JaroslavTulach 09:21, 15 June 2015 (UTC)

Is localizing an API bad idea? - 2015-05-31 07:48:00

What is the relation between I18N and API design? Should API be internationalized and localized?

--JaroslavTulach 07:48, 31 May 2015 (UTC)

Java Modularity in the Context of JavaScript - 2015-05-29 04:10:00

Obfuscation per library is quite common in JavaScript and it results in faster download times, sharing modules between different applications and easier processing of the obfuscated files. Shouldn't something similar be done in Java?

Yes, it should. And it has been done! Here is description of design and implementation of Obfuscation per JAR file for Java (in a [[Bck2Brwsr|browser).

--JaroslavTulach 04:10, 29 May 2015 (UTC)

API Design as a Service - 2015-05-17 10:26:00

Domain Expert is a person who has knowledge of a particular system. With such knowledge it may seem easy to design APIs for the domain. However without understanding the API Paradoxes the quality of such API may not be high. It is likely going to cover the domain field, but the API usability or readiness for evolution will very likely suffer (unless such Domain Expert reads TheAPIBook first).

However can it work backwards? E.g. can one be just an API expert and then design good enough API without appropriate domain knowledge?

I am now participating in an experiment that will check that. OracleLabs guys asked me to help them design Truffle interoperability APIs. I do understand bit about Truffle, but certainly I am not a Domain Expert, yet I am supposed to design something as complicated as API to allow mixing of languages: imagine part of program written in Ruby, part in JavaScript, part in Java with objects floating between these languages without any borders!

This is a new situation for me: In case of NetBeans or in case of HTML/Java APIs, I was also the architect of the system. I knew it by heart. Now I barely understand how Truffle works and what makes it the fastest execution system for dynamic languages. My biggest fear is that I will design something that will be inherently slow.

On the other hand, I am not yet damaged with the expert knowledge. I can still see the system with new comer eyes - just like you, users of Truffle will. As such I can perform a usability study on me, at least initially.

If I can design easy to use APIs for Truffle, then I can create a perfect API facade around everything! Soon we'll have a chance to see whether one can be good API designer without being real Domain Expert. Soon we'll find out if API Design can be offered as a service!

--JaroslavTulach 10:26, 17 May 2015 (UTC)

JavaScript is the x86 of the Web - 2015-04-22 07:00:00

Brendan Eich, the inventor of JavaScript: I said 'JS is the x86 of the web' ... the point is JS is about as low as we can go..., here is a video to document the current JavaScript situation together with showing excellent demos as a proof:

--JaroslavTulach 07:00, 22 April 2015 (UTC)

Gradle belongs to Stone Age! - 2015-03-15 15:56:00

My friends keep talking about the greatness of Gradle. It is hard to stand it, especially knowing there is a significant flaw introduced in Gradle's core.

The flaw is so huge that I rank Gradle along Ant. Into Ant-age!

--JaroslavTulach 15:56, 15 March 2015 (UTC)

ConfigurationObject Pattern in Java - 2015-02-22 12:44:00

ConfigurationObject pattern is quite common in many JavaScript libraries. Do you know what is the best way to express it in Java? Check my essay that compares four different ways and analyses their impact on API designer and especially API users.

--JaroslavTulach 12:44, 22 February 2015 (UTC)

Final interface. Finally Done Right! - 2015-02-04 16:53:00

Maybe there is nobody interested in final interface API Design Pattern anymore! Now when there is JDK8 with extender methods people may always mitigate bad design (e.g. using final interface at all) by adding methods with default bodies. Still I found it important to cover this pattern in my API Design Patterns Collection.

Let's me guide you through the short and incomplete history of final interface design pattern with small excursion to JDK's own itches and specifics of designing for OSGi to finally describe how to do final interface pattern right!

Let you find such description useful!

--JaroslavTulach 16:53, 4 February 2015 (UTC)

Impossible. Part II. - 2015-01-03 19:23:00

Everybody understands threading is complex. Yet almost everyone believes that with good methodology it is possible to do threading right. Well, it is not. There is no theory to eliminate deadlocks. Achieving proper threading is impossible. Still people keep asking for it. When you tell them it is impossible, you may get fired. Just like me few years ago! Here is my story.

--JaroslavTulach 19:23, 3 January 2015 (UTC)

BinarySelection - #1 Rule of HR - 2014-12-23 06:20:00

BinarySelection plays (except having its classical search meaning) an important role in theory of HR management. It defines what happens when employees are leaving the employer (either voluntarily or after being fired):

BinarySelection means, that "ones" leave and "zeros" stay.

I mention this definition whenever we chat about life of software developers and it always generates grin smile. Of course, because it is so true! I can confess that as for last seventeen years I have been sticking with my job surviving any layoffs and acquisitions: I've seen so many "ones" leaving, but the rest of us is still marching on!

--JaroslavTulach 06:20, 23 December 2014 (UTC)

Publish Bck2Brwsr Libraries as Maven Artifacts - 2014-12-07 05:21:00

Bck2BrwsrLibraries can now be published as Maven Artifacts which greatly reduces edit/compile/run time.

--JaroslavTulach 05:21, 7 December 2014 (UTC)

Converting Truffle - 2014-11-29 13:07:00

I've just converted Truffle to OSGi bundle with following simple script. As I was interested only in PolyglotEngine class, I exported just the single package:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
                        <!-- I am interested only in PolyglotEngine -->
                        <!-- list other packages that should be included in your bundle -->

--JaroslavTulach 13:07, 29 November 2014 (UTC)

Duke Choice Award

DukeScript has been awarded a Duke Choice Award! Here is picture of Toni Epple and me holding the Duke Choice Award on Sep 28, 2014:


Long live Java and HTML on every device (iOS, Android and co.)!

--JaroslavTulach 17:37, 29 September 2014 (UTC)

Play MineSweeper to Become iOS, Android, JavaFX & co. Developer

Since Sep 15, 2014 the MineSweeper NetBeans integration can be used as a starting point to develop own DukeScript applications. Just press the Develop button and a new project wizard will be opened as following picture shows:


--JaroslavTulach 10:57, 15 September 2014 (UTC)

JavaOne2014: Need Speakers for My Session!

JavaOne2014 is around the corner and my sessions have been scheduled. I start with a BOF on Monday evening called Virtually Inside-Out! - it is going to be discussion between authors of alternative JVMs. So far we are two: I have mine Bck2Brwsr and Niklas has RoboVM.

Don't you know a developer working on own JVM who will be at JavaOne2014? If so, please tell him to contact me and stop by! I plan to make the BOF a lively chat (how did you implemented lambdas?, how did you implemented defender methods?), but in case we don't have a topic to talk about, I am ready to explain why value classes should not be in JVM and why InvokeDynamic is a completely stupid idea. Anyone from JDK team to defend these proposals?

On Tuesday morning Toni and me will continue with DukeScript tutorial. In case you use Java and want to learn how to code for iOS, Android, JavaFX and browsers, stop by. We will help you create your first application that is written once and displayed anywhere!

I'll finish on Tuesday noon talking about API Design checklist. I'd like to name at least ten things one should check for, but so far I have about two. Don't you have any idea what could be in such checklist? If so, please talkback!

--JaroslavTulach 18:56, 10 September 2014 (UTC)

Develop in NetBeans and Deploy to AppStore

Minesweeper for iOS has been published. First iBrwsr powered DukeScript application has been deployed to AppStore. If you own an iPad or iPhone, give it a try: https://itunes.apple.com/us/app/fair-minesweeper/id903688146

And don't forget you can use NetBeans to develop such applications yourself! Install DukeScript NetBeans support.

--JaroslavTulach 15:29, 21 August 2014 (UTC)

Develop in NetBeans and Deploy to GooglePlay

Minesweeper for Android has been published. First DlvkBrwsr powered DukeScript application has been deployed to GooglePlay. Give it a try: https://play.google.com/store/apps/details?id=org.apidesign.demo.minesweeper

And don't forget you can use NetBeans to develop such applications yourself! Install DukeScript NetBeans support.

--JaroslavTulach 05:17, 31 July 2014 (UTC)

Japanese Translation is Real

Cover of Japanese translation of TheAPIBook. I am amazed, the book is about 30% shorter, yet is seems to contain all the content of the original one!


Great work Yoshiki!

--JaroslavTulach 06:51, 17 July 2014 (UTC)

Bck2Brwsr Revision 0.9 is Released!

Version 0.9 eliminates useless stack assignments. Instead of doing

var stI0 = lcI0;
var stI1 = lcI1;
var stI0 = stI0 + stI1;
return stI0;

the now generated code is

return lcI0 + lcI1;

which is shorter and more human readable. However I doubt the V8 virtual machine sees any benefits - I think the final native code remains the same. But at least the debugging of the generated JavaScript code is now easier - there is less Step Over invocations and it mimics more closely the original Java source.

Optimized the ahead-of-time compilation, so now the http://xelfi.cz/minesweeper/bck2brwsr/ demo starts up instantly. I had to do it, because it was so embarrassing to see TeaVM to boot the same application so quickly: The initial delay is gone, and moreover it downloads necessary libraries in parallel and on background. Now we are ready for next step: share the libraries between different applications.

Can ObfuscatePerLibrary - e.g. each JAR gets compiled ahead-of-time into its own JavaScript file, which can be shared between many applications.

--JaroslavTulach 06:34, 10 June 2014 (UTC)

Podcast related to Japanese Translation

Japanese translation announcement: --JaroslavTulach 18:45, 2 June 2014 (UTC)

Debug Mixed Java/JavaScript Applications

Before Nashorn (the JDK8 JavaScript engine) performing calls between Java and JavaScript was a pain. Especially when it came to debugging. But now, one can completely freely mix Java and JavaScript inside of a single thread and still be able to debug and inspect the slightest details of Java as well as JavaScript stack frames.

See video showing the power of the synergy between NetBeans 8.0 and Nashorn!

--JaroslavTulach 15:53, 20 February 2014 (UTC)

Japanese Translation of Practical API Design

The Japanese translation of my book has been in progress for several months. Recently I've been asked by Yoshiki to write a preface.

I wrote one and I tried to express how wonderful experience it had been to participate in the Japanese translation. I believe the Japanese version of my book will be great.

Thanks Yoshiki for your work. Dear (Japanese reading) readers, enjoy!

--JaroslavTulach 09:28, 27 January 2014 (UTC)

Unify Eclipse and NetBeans UI

I've managed to prototype a way to share UI between two rich client platforms. These days it is popular to use HTML, so I did it. However in addition to that I managed to remove all need for JavaScript. Design in HTML and code your application logic in Knockout4Java.

See how!

--JaroslavTulach 18:01, 21 December 2013 (UTC)

JavaFX for iOS via NetBeans

I am pleased to announce there is now a way to develop applications for iOS using your favorite language (I mean Java) and your favorite development IDE (I mean NetBeans).

With the help of Prague's JavaFX iOS team we now have a NetBeans plugin that helps anyone develop JavaFX based Java apps for iOS. Many thanks should also go to RoboVM guys for creating such easy to use Maven plugin.

Enjoy JavaFX on iOS!

--JaroslavTulach 12:42, 10 December 2013 (UTC)

API Design Guidelines

I have discovered a nice checklist of guidelines considered good for API design.

--JaroslavTulach 09:30, 2 December 2013 (UTC)

Cloud IDE for Kids

Scratch is getting better and better. If you have not done that yet, give it a try!

--JaroslavTulach 08:48, 2 December 2013 (UTC)

The Smallest Linux JDK

The profiles support is coming for JDK8. Not only it is coming, it works! In case you are searching for a small Java, give profiles a try. They are easy to start with.

--JaroslavTulach 15:12, 27 November 2013 (UTC)

DEW - Java Meets Web with Your Help!

I'm proud to announce DEW - the development environment for web (of course in Java). I am tired of observing JavaScript being on the rise while pretending it is more than just a script language. The real language is Java and it does quite well with HTML. Check DEW here: http://dew.apidesign.org/dew/ and you will not regret!

The more you fiddle with DEW and the more you alter (and save) the samples, the more we will help Java get Bck2Brwsr!

--JaroslavTulach 16:56, 28 October 2013 (UTC)

Maven and Bck2Brwsr 0.8

I've just updated instructions to use bck2brwsr 0.8 from command line. Me and Jonathan Fuerth also verified that the Bck2Brwsr Maven archetype can now be used in Eclipse.

Nothing can stop us from bringing Java Bck2Brwsr!

--JaroslavTulach 12:22, 29 September 2013 (UTC)

Use the Debugger, Stupid!

Debugger is a very useful tool. I greatly recommend it to everyone who asks stupid questions on mailing lists and reports vague bugs into bug tracking systems. If your application does not work: use the debugger! Read here to learn how.

--JaroslavTulach 09:17, 20 August 2013 (UTC)

Bck2Brwsr 0.7 Released!

Write applications once and deploy them to FXBrwsr as well as Bck2Brwsr:

--JaroslavTulach 07:50, 9 May 2013 (UTC)

Bck2Brwsr 0.6 is Released!

Now you can write your own real applications for browser in Java:

  • Full featured demo Twttr demo
  • Bck2Brwsr provides better binding of complex classes (defined by a special @Model) annotation
  • The @Model classes can be obtained from a server via JSON and JSONP. Use @OnReceive annotation
  • Browser testing harness has nicer output with UL and expandable LI

--JaroslavTulach 21:24, 14 April 2013 (UTC)

Older Blog Posts


--JaroslavTulach 21:00, 14 April 2013 (UTC)

Bck2Brwsr and Images as Resources - 2014-10-30 01:19:00

Blob URL support has been implemented for forthcoming version of Bck2Brwsr 0.12. Now you can easily access images packaged as resources in your JAR files and obtain their browser valid URL.

--JaroslavTulach 01:19, 30 October 2014 (UTC)

Impossible. Part I. - 2014-10-20 14:25:00

Explaining that something is impossible is, well impossible! Here is a link to one viral video and one story from my computer science student years, which is so true, I would almost cry. In case you find my impossible story interesting, let me know. I have at least two more on the same impossible topic!

--JaroslavTulach 14:25, 20 October 2014 (UTC)

invokeDynamic is wrong idea. Especially for implementation of lambdas! - 2014-09-25 12:50:00

When I was younger I used to believe that having invokeDynamic instruction in JVM can be beneficial. Now, few years later and after spending time to implement lambdas in my Bck2Brwsr VM and seeing things from the other side I have to admit I was wrong. invokeDynamic is wrong idea (especially for implementation of lambdas).

It is JavaOne time, I have a talk about my Bck2Brwsr together with Niclas from RoboVM, so let's show I understand what is wrong with JVM and start a little rant! I need something from the JDK guys, so let's give them a reason to welcome me with open arms when we see each other in San Francisco:

InvokeDynamic should have never been added to Java and should be removed from the specification. Read why...

--JaroslavTulach 12:50, 25 September 2014 (UTC)

Lambdas Go Bck2Brwsr! - 2014-09-15 17:48:00

Bck2Brwsr 0.10 has just been released. The most important thing to note is that it handles JDK8's lambdas. See the illustrative video:

The JDK emulation library is still based on JDK7, so don't expect your streams & co. code to run. I'll update to JDK8 after JavaOne2014. Meanwhile enjoy lambdas in your own APIs!

--JaroslavTulach 17:48, 15 September 2014 (UTC)

Sources for the Practical API Design book - 2014-08-08 11:16:00

Hear the news: Sources in ZIP format are back!

My Hudson server crashed in early months of 2014. I had to configure it from scratch. While doing so, I forgot to configure the job to produce apidesign.zip file with sources. Has anyone noticed? Nobody sent me an email! Just yesterday Jáchym, my co-worker, who I torture by forcing him to read TheAPIBook and become good API designer, stopped in my office and timidly asked: Where can I get the sources? There is no ZIP file!

For a while I tried to blame him for not using Mercurial, but after a while I realized the problem is on my side. As a result, the zip file with sources is back as of Aug 8, 2014. Will anyone use them? It would be nice as reading Practical API Design book without having whole sources at your hand is like trying to understand Swing just by reading its Javadoc.

--JaroslavTulach 11:16, 8 August 2014 (UTC)

Use NetBeans to Deploy Everywhere! - 2014-06-18 11:09:00

Client Java everywhere is now possible thanks to essential part of DukeScript - its capability to deploy to almost any device on the planet (that can render HTML). One can configure everything in an IDE independent way, but the best way to start is to get your instance of NetBeans 8.0 and follow few easy steps described in the official DukeScript getting started document.

--JaroslavTulach 11:09, 18 June 2014 (UTC)

MineSweeper on iOS - 2014-05-21 14:13:00

Thanks to IBrwsr I managed to run my favorite game on my iPad! Why don't you write applications that run on every device, yet?


--JaroslavTulach 14:13, 21 May 2014 (UTC)

Epistemology of Software Design - 2014-05-15 20:01:00

Epistemology of software design by Nathan is online! I greatly recommend it to everyone who wants to produce software that lasts! After all those years with NetBeans I can only confirm everything Nathans describes!

If you want to stop being a software engineer and become software architect, epistemology of software design is one of the things you have to memorize!

--JaroslavTulach 20:01, 15 May 2014 (UTC)

Lower Your Profile! Adopt JDK8! - 2014-03-23 11:40:00

By lowering profile of our libraries, we can make them more ready for JDK8. Here is few patterns one can use to adopt own library to JDK8 profiles.

Lower your profile, let (your library usage) get higher!

--JaroslavTulach 11:40, 23 March 2014 (UTC)

TeaVM Can Execute DukeScript Applications! - 2014-03-20 14:27:00

Alexey just released his first version of TeaVM. Congratulation!

Well, everyone now writes virtual machines that run in a browser, but TeaVM is special - rather than separating and playing on its own sand field - Alexey decided to speak DukeScript. As a result, the same application can now be deployed to Bck2Brwsr and TeaVM and we can compare which virtual machine is better - or at least play minesweeper 1 and minesweeper 2.

Enjoy and give DukeScript (the JavaScript, the way it was meant to be) a try!

--JaroslavTulach 14:27, 20 March 2014 (UTC)

Avoid Synchronization Problems - 2014-02-14 16:24:00

Don't let your objects escape from your methods! As suggested on page 193.

--JaroslavTulach 16:24, 14 February 2014 (UTC)

It, this and that: Optimizing for Cost of Ownership - 2014-02-11 10:53:00

As paragraph on page 154 shows, it is not easy to find out what a meaning of it, this and that may be. Thanks Yoshiki for contributing this first Errata for Chapter 9!

--JaroslavTulach 10:53, 11 February 2014 (UTC)

Good Advice - 2014-02-06 08:04:00

How do you recognize Good Advice? We already know what a good technology is, can we use the same concept to evaluate whether an advice is good or not? Let me answer that by a quote from TheAPIBook which Yoshiki asked about:

Page 363

Part 1 presents all of API design as a scientific discipline with a strong rational background, not as the art that it sometimes pretends to be. It defines terminology and initial prerequisites that can objectively help us measure if an API design is good. These rules try to be language neutral and applicable to any programming language, not just Java. The theory is unlikely to be complete. Other principles of API design exist elsewhere or are still waiting to be discovered.

However, that should not scare us, as Chapter 1 gives us a tool to evaluate the quality of various principles to find out whether a certain piece of advice helps us design better shared libraries and their APIs or not. It gives us the grand meta-principle: selective cluelessness. This cluelessness is a tool that can measure whether various goals really help. That’s because if they allow people to know less while achieving more and building better software systems more easily, then this advice is good. There is a need for this advice, especially in the future, when software systems will outsize the intellectual capacity of any of their designers.

Yoshiki: What do you mean by this advice?

"this advice" is a reference to advice mentioned in "to find out whether a certain piece of advice helps us design better shared libraries". To rephrase: any advice that helps users increase cluelessness is good and it will be even more valuable in the future when we start to build even bigger systems.

--JaroslavTulach 08:04, 6 February 2014 (UTC)

Changes: HTML for Java, videos and hosting - 2014-01-14 08:24:00

I'd like to announce few changes related to apidesign.org site.

First of all, the Knockout4Java is now a NetBeans subproject and yesterday I managed to release its first bits as a stable version 0.7 - follow three simple steps to see how powerful Java/HTML user interface can be.

The other change is that I am migrating the whole website to new hosting infrastructure. Sources are up, mediawiki as well. However I still need to recover mailing lists, etc. If you find something that is not working and should, please Talkback. Thanks in advance.

One thing you don't have to complain is lack of videos - this is what one gets when using a cloud service! My uploaded screencasts had been found inappropriate and were deleted - after four years of being OK! Should I upload the backup copies (that I can find) elsewhere or rather host it myself?

--JaroslavTulach 08:24, 14 January 2014 (UTC)

Pervert Your Language to Become a Better Programmer - 2013-10-16 13:02:00

Language that you speak and write defines what you can think and reason about. The worse language you can use the better programmer you are. Right?

--JaroslavTulach 13:02, 16 October 2013 (UTC)

Do You Know What a WeakReference Can Do to Your API? - 2013-10-11 08:50:00

References and WeakReferences play important role when designing an API contract or building a framework. Are you sure you use them properly? Read about problems we had when messing with WeakReferences in the Lookup API.

--JaroslavTulach 08:50, 11 October 2013 (UTC)

Can Deserialization Change Value of a Final Field? - 2013-09-23 16:58:00

Deserialization can change value of a final field. See the code snippet to understand how. 1st lesson learned at JavaOne2013.

--JaroslavTulach 16:58, 23 September 2013 (UTC)

The Art of Writing Equals in Object Oriented Languages - 2013-09-06 08:53:00

Do you think you know how to write equals? Are you sure? Take your time. Still sure? Check this example to verify.

--JaroslavTulach 08:53, 6 September 2013 (UTC)

JDK8's Profiles in the Light of Harmony - 2013-08-12 14:54:00

A curious translator of my book asked me about project Harmony. That motivated me to sit down and write an incomplete and mostly wrong history of open source java implementations. While incomplete (for example it does not talk by whom Harmony was founded and why), it explains why JDK8 is/will be a huge step forward and what will be its most important feature. Btw. if you thought lamdas, you were wrong.

--JaroslavTulach 14:54, 12 August 2013 (UTC)

Bck2Brwsr Goes Server Side: Run the Same Code on Server and Client! - 2013-05-20 12:45:00

I'd like to introduce my small contribution to Jersey project. It provides (yet another, but this time very lightweight) converter from Java to JSON and back. Together with Bck2Brwsr or FXBrwsr you can now smoothly execute the same Java code on client as well as on your server.

--JaroslavTulach 12:45, 20 May 2013 (UTC)

Introducing Knockout4Java - 2013-05-16 21:32:00

Knockout4Java takes the best of two words: The type safety of Java and Knockout.js ability to alter any HTML page in any browser. Write your models in Java (using JSON4Brwsr library) and render them as HTML with the help of Knockout4Java!

--JaroslavTulach 21:32, 16 May 2013 (UTC)

Introducing FXBrwsr - 2013-04-30 09:25:00

FXBrwsr is an attempt to give people the rendering power of HTML (via Knockout.js) and the benefits of HotSpot Java VM. As the Twitter example shows, it is then easy to deploy the application to run Bck2Brwsr.

--JaroslavTulach 09:25, 30 April 2013 (UTC)

Cimrman's Planning - 2013-03-19 15:10:00

Short introduction to accurate, agile, modern, reliable, flexible, optimistic, forward looking, experience based, projective planning methodology.

--JaroslavTulach 15:10, 19 March 2013 (UTC)

Javadoc for Coding for Your Browser Published! - 2013-03-01 09:11:00

I've just set a job up to generate Bck2BrwsrJavadoc. Anyone wants to design a library for the browser?

--JaroslavTulach 09:11, 1 March 2013 (UTC)

Platón's Theory of Ideas for Developers - 2013-01-21 08:45:00

Those of you who heard about Platon in school probably also hard about his allegory of a cave (at least I did when I was at high school). It is not often easy to imagine what Platon meant by the cave, shadows, etc. Luckily (at least for developers who know what geometry is), there is a better explanation which which explains Platon's theory of ideas via geometry.

This geometric way of explaining [[ideas was much easier for me to swallow. That is why I decided to share it here.

--JaroslavTulach 08:45, 21 January 2013 (UTC)

On the fact that the Atlantic Ocean has two sides - 2013-01-17 11:56:00

Here are selected notes from my favorite write up by Edsger W. Dijkstra (the guy that invented semaphore). Few decades has passed since the initial publication and the difference between U.S. and Europe may not be as sharp anymore. Still, a lot of Dijkstra's comments apply - especially when it comes to the clash between programmers educated in soft vs. real science schools!

Btw. should this kind of analysis be found interesting, I can share another one: Why our U.S. friends can't read maps and are not aware of that. Just let me know if I should publish it.

--JaroslavTulach 11:56, 17 January 2013 (UTC)

Having a Hammer All Problems Look Like a Nail - 2012-11-12 13:37:00

A theoretical observation about a hammer with application to real world scenario as well as software user interface design.

--JaroslavTulach 13:37, 12 November 2012 (UTC)

TransitivityOfIncompatibleChange - 2012-11-07 02:00:00

A nice clash between real world and academic attempts to describe it can be seen on the case of TransitivityOfIncompatibleChange. While such transitivity is an easy to grasp concept, it is too simplistic and often too hard to apply for the real world of software dependencies. It took me a while to understand its alternative, but now I think I see it.

Last week I had a presentation about the topic of NP-Complete problems in module dependencies at MatFyz and one of the questions was: Why am I not using TransitivityOfIncompatibleChange in case of repositories with RangeDependencies? Well, I don't as it does not have a clear meaning. But the question forced me to sit and write the answer down.

Hopefully not only MatFyz guys find the essay useful.

--JaroslavTulach 02:00, 7 November 2012 (UTC)

Is Java a Language or a Framework? - 2012-10-18 09:06:00

Just a few thoughts about the difference between language and a framework (plus a wish how Java should evolve).

--JaroslavTulach 09:06, 18 October 2012 (UTC)

20 API Paradoxes Published! - 2012-10-11 18:11:00

Today I am ready to announce great news. My new book about 20 API Paradoxes is now publicly available. I'd like to thank everyone who helped me get it to e-readers all over the globe. Jeff corrected my English and made the structure of the book more consistent. Clay stopped me when I wanted to expand the scope and delay the publication. And, most importantly, Clay is responsible for this fantastic cover:


I asked Clay to select cover that would somehow reflect my relation with my home and I am glad he decided to use painting of Josef Lada - a painter of my childhood.

I hope you like the cover too. And not only that, I hope you'll like the content as well. Buy & enjoy!

--JaroslavTulach 18:11, 11 October 2012 (UTC)

C++ May Not Be As Bad As Thought! - 2012-09-27 07:40:00

Do you remember my recent post about object oriented encapsulation and performance? It was written in a response to an article that claimed C is much better than C++. There in given example nicely illustrates that by giving up on encapsulation one can implement more effective linked list. In my recent post I managed to prove that by using traits, one can easily get the same performance while keeping encapsulation in modern object oriented language. Only one question remained: Can one do the same with C++ templates?

I am glad to report we have an answer with a sample code. There is a way to write generic template (well two of them) and orchestrate them in a way that keeps encapsulation and maintains the C linked list performance. C++ is not as bad as I thought.

Last note related to this incident (influenced by book I am currently reading). There are tons of comments attached to the original article yet most of them are really shallow. Usually along the line of that is a non-sense!, use STL! or C rules, I knew it!. I guess this has something to do with Thinking, Fast and Slow: people were provoked to react instantly by seeing a topic they had already have an opinion about. Without really giving the issue a though, they replied using fast thinking.

It took me a weekend to come up with the trait solution and we needed about a week to polish the C++ sample code. Looks like a little bit of slowness can worth tons of fast made opinions. But that is for another story - first of all I need to finish reading Thinking, Fast and Slow book.

--JaroslavTulach 07:40, 27 September 2012 (UTC)

Older Blog Posts - 2012-09-27 07:00:00


--JaroslavTulach 07:00, 27 September 2012 (UTC)

100th Monkey Principle. Multicasting in a Nature? - 2012-08-08 19:29:00

James Borowski on 100th Monkey principle:

Found reading some stuff on your site really interesting. I have not finished reading yet, so, forgive me if you already know this, but I was reading the article DiamondsVsStars and wondered as I read your comments regarding the "something in the air" as people around the world all discover something at the same time, if you were aware of the 100th Monkey principle?

There are different versions of the tale, but essentially, there was an island with a load of monkeys that learnt a trait one at a time of how to knock nuts with a rock to get inside them (other versions of the story are about learning to wash them, but the principle is the same). It took a while for monkeys to copy each other, one at a time, and the speed of uptake was essentially linear and at a fixed rate until they reached the 100th Monkey. At this point, every monkey on the island, and every monkey on the three neighbouring islands all started the same trait, almost instantly. The point is: A species appears to be connected at some vibrational level to the extent that they share certain thought processes/notions. There is a tipping point (apparently this is the square route of 1% of the population pool / or 100 monkeys ) where once reached, this information is availiable to all. Almost as if an entire species are listening on the same multicast address.

Anyway, hope you find as interesting as I found your stuff. For more info see 100th Monkey at wikipedia.

Thanks, for sharing this observation, James!

--JaroslavTulach 19:29, 8 August 2012 (UTC)

How Strict a Backward Compatibility Should Be? - 2012-07-31 12:13:00

Here are some thoughts on the difference between 100% BackwardCompatibility and their slightly more practical variants.

--JaroslavTulach 12:13, 31 July 2012 (UTC)


Enums in APIs - 2008-07-16 14:18:00

An user of an enum might want to ensure he has processed all its fields. This can be problematic when the user doesn't own the enum, such as in an API.

--AndreiBadea 14:18, 16 July 2008 (UTC)

Question on classes and interfaces - 2008-07-15 09:33:00

Someone asked: I guess that, roughly, a client API should use abstract classes while a support/provider API should use interfaces?

To which I responded...

--JesseGlick 09:33, 15 July 2008 (UTC)

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