Weiqi Gao's Observations

Friday Java Quiz: Know Your JDK

Fri, 11 May 2012 12:48:36 GMT

Haven't had one of these for a while. I was busy doing other things.

Since it's been so long, I'll pose an easy quiz today:

Q: What does the following command print?

weiqi@gao /opt/jdk1.7.0_04/bin$ ls | wc -l

(/opt/jdk1.7.0_04 is where I installed my JDK, your JDK installation locations may vary.)

Strict rules apply today: You have twenty minutes to think about it and you must write down your answer before you go to your JAVA_HOME and run the command.

Software Engineering Tech Trend (SETT): Experiments With JavaFX 3D Scenes

Wed, 02 May 2012 03:28:20 GMT

The last article I wrote for OCI's online newsletter Java News Brief (JNB) was Six JDK Classes You Think You Know, which several readers have told me was fun. That was the last article in the JNB series. The following month, the series began its publication under the new name Software Engineering Tech Trend (SETT), with an expanded scope covering a broader array of software engineering topics. Here's a sample of the articles that was published in SETT in the last year and a half:

In this months SETT article, Experiments With JavaFX 3D Scenes, I show you one aspect of JavaFX, its 3D scenes support, through a set of experiments that go from simple animated squares moving along straight lines to an animated formation of a tetrahedron in 3D. I was hoping to show you an animation of a dodecahedron being formed from a stack of pentagons,but I ran out of time for the article and have to settle for a tetrahedron there.

I did, however, finish an animated dodecahedron after I submitted the article. And here is how it goes:

Enjoy!

An Updated JavaFX 2 Applet: Pythagorean Theorem

Wed, 04 Apr 2012 12:25:27 GMT

Oracle announced the EOL (end of life) for JavaFX 1.2 and 1.3 36 days ago:

javafx4you: Today, we are announcing that JavaFX 1.2 and JavaFX 1.3 will reach end of life (EOL) on December 20, 2012. More specifically, the Oracle server providing access to the JavaFX Runtime for these versions will no longer be available after that date.

So I spent some time in the last couple of days to update one of my JavaFX 1.1.1 applets published on this blog—an animation that depicts a proof of the Pythagorean Theorem. It appeared in Zhou Bi Mathematical Manual (周髀算经) which I wrote 1061 days ago. I wanted to update this applet because people have told me that it helped them or their kids to understand the Pythagorean Theorem better.

JavaFX 1.x code, which is in JavaFX Script, translates easily into JavaFX 2.0 code, which is simply Java. The two facilities of JavaFX 1.x that made the original applet work, bindings and animations, are major APIs in JavaFX 2.0. And the porting is almost mechanical. Naturally the Java code is more verbose than the equivalent JavaFX Script code. But that's the price we pay for converting JavaFX into the wider-reaching Java APIs.

While I was at it, I added a background image that was merely put side by side with the applet in the original post. Since JavaFX 2.0 applets only works on Windows, I have put the applet on a separate page here. The source code is here. The background image is here. The following is a video showing the applet at work. Notice the actual jpg file is bigger than the applet's Stage size. I used a viewport on an ImageView to pick out a portion of the image.

Your browser does not support HTML 5 video. Here's the link to the video file.

Enjoy the elegance of geometry and JavaFX.