Using CSS in JavaFX to keep the API clean

  • Post category:JavajavafxUI

As a notorious skeptic, the usage of CSS for styling in JavaFX to me was something of a “yeah, nice, but we’ll see how it works out.”. There are some doubts in how CSS will work out when complete skins (like Synthetica for Swing) are created, in combination with third party controls. But last week I had a situation that won me over to the “it’s good” side.

A user of one of my controls, CalendarPicker in JFXtras, came to me and told me about their usage of the control. They had integrated it in their application and styled it Windows 8 alike using CSS. But, he said, our graphical designer wants the arrows of the month and year selector to be on either side of the value, and the value centered instead of left aligned. Shown below is the default UI for CalendarPicker and as you can see, it is not as the designer wants:



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Supporting JSR310 (Jodatime) in JFXtras

Probably everyone is exited that Oracle is finally picking up the highly dubious date time implementation in Java called Calendar. It is interesting to see that large companies like Sun really have problems getting something as seemingly simple as date and time implemented correctly. Of course there are two sides to the problem, first there are all the intricacies of date and time, like time zones and other more or less subtle problems (this is where Date went wrong). And secondly there is the implementation aspect, where for 99% of the usages a date or time is considered an immutable value, like a number, easy to use for a developer (this is where Calendar went wrong, just take a look at the output of toString()).

Now, there are reasons why there is a CalendarPicker and not a DatePicker in JFXtras. And the primary reason is that Calendar has a notion of locality, which Date has not; for example in Germany the week starts on a different day (Monday) than in the USA (Sunday).



Calendar actually is pretty decent when it comes to the domain of dates and times, Jodatime is added to Java 8 is because the implementation, the API, is bad. (more…)

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Layout in Android (and JavaFX)

One of my clients allowed me to write an Android application. I have done Java and mobile development before, so it basically comes down to learning the new framework. And that’s something Java developers do on a fairly regular basis. There were some special things, like connecting to a bluetooth barcode scanner, but nothing that some coding-by-googling wouldn’t fix. The application initially was aimed at Android 2.2+ and phones, but in the meantime it’s been upgraded to Android 4.0+ and 10″ tablets, because it needed a stronger visual screen (with loads of images) and the screens of the phones were simply too small.I’d like to share some of the experiences I had with this project.



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JavaFX layout, a silver lining?

  • Post category:JavajavafxUI

As described in the previous post, I believe that JavaFX’s layout mechanism is not as good as it could (should) have been. Naturally it is one thing to complain, another to offer improvement suggestions, but the best is to provide alternatives. First there is MigPane, which is a very powerful layout manager, but it is also possible to ‘slap’ on a different API onto existing layout managers. And that is what is being attempted in the JFXtra’s drop-in replacement layout managers. These layout managers extend the existing one, but add a different style.

The basic idea is that instead of writing:

VBox lVBox = new VBox(5.0);
Button b1 = new Button("short");
VBox.setVgrow(b1, Priority.ALWAYS);

You can write:

VBox lVBox = new VBox(5.0);
lVBox.add(new Button("short"), new VBox.C().vgrow(Priority.ALWAYS));


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It’s not all gold and sunshine; JavaFX layout

  • Post category:JavajavafxUI

After my previous post, praising the properties and binding mechanism, I’d also like to voice an opinion on something on which I think the JavaFX team has dropped the ball.

In the previous post about Agenda control I explained that there were two ways I updated the nodes in Agenda; either I setup binding in the constructor, or I listen to relevant properties and call a relayout() method, setting the appropriate values there. Especially the binding is a powerful feature. No software engineer can deny that the sniplets below don’t have a certain beauty to them.

Adding a rectangle that serves as a dragger at the bottom of an appointment:

durationDragger.xProperty().bind(widthProperty().multiply(0.25)); // 25% offset from the left border
durationDragger.widthProperty().bind(widthProperty().multiply(0.5)); // 50% of the width of the appointment
durationDragger.yProperty().bind(heightProperty().subtract(5)); // 5 pixels from the bottom border
durationDragger.setHeight(3); // 3 pixels high

Making sure the day head and day body line up:

dayHeader.xProperty().bind( dayBody.xProperty());
dayHeader.widthProperty().bind( dayBody.widthProperty());

What is important here is that the x,y,w,h values are set directly on the children. The container does not do any layout, it simply draws its childeren where they say they want to be. This is called an ‘absolute’ layout. All other layouts (VBox, HBox, BorderPane, …) do not want you to set the x,y,w,h of the children, their added value is that they’ll calculate and set them for you. (more…)

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Writing Google Calendar in JavaFX

  • Post category:JavajavafxUI

After getting my feet wet writing the ListPicker and CalendarPicker control in JavaFX for the JFXtras project, I felt it was time to put my aim at something bigger; I always wanted to write a control that does a “Google Calendar”. Even though such a control on the surface seems simple, there are many things that make it a real challenge and fun for a software engineer to create. For example the beauty of how overlapping appointments are rendered. So after a few days where the spare time went into drawings and scribbles on paper, fleshing out how things should be set it up, the coding started. There were a few things I would like to do different from Google’s version.

  1. When I plan an appointment, I always forget to look at the whole day events, and often get conflicts because of that. So I wanted a whole day event to have a presence during the whole day.
  2. Google only allows for appointments that span a certain amount time. Tasks (which basically only have a single date & time) are not supported. Google has a task feature, but it is not mature enough IMHO in terms of reminders and visibility.

So before diving into how the control is set up, first a quick peek at the state of affairs when writing this blog (tasks are not implemented yet):


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Stand alone business model with Activiti, Eclipselink and unit tests on PostgreSQL

Somewhere around 2007 – 2008 I was setting up a new project which had a business model (BM) as the central component. The business model I envisioned had a three layered structure: an AbstractBean handling all the Java bean plumbing, a from-the-database-reverse-engineered class with the properties (setters and getters), and finally a class containing the custom code on top. I wanted to settle on a standard (JPA) and tried using Hibernate at first, but it could not support this layered structure back then, so I ended up using Eclipselink (and with great satisfaction ever since, I must add).

I also have never been a fan of pure application servers (EJBs), so this BM is compiled into a single jar (already postprocessed by Eclipselink), and simply included in all kinds of applications; a client-server Swing application, a REST interface to support an Android app, several im- and exporters for EDIFACT, emails, XML, and of course a nice in-house webapp. Not having an additional single point of failure (besides the database) is very pleasing and keeps the overall architecture much more simple. (more…)

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Customer support by D-Link

In the age of digital TV, video reaches the screen in your living room in many ways. Currently my TV gets an analog and DVB-C signal through the COAX cable, and the cupboard beneath my TV holds a VCR, DVD player, media streamer and a HDTV box. The latter two receive their data through UTP ethernet connections. The problem naturally is how to get the UTP to those two boxes, because most houses are not equipped with UTP cabling. My home is fairly new (build in 2004) and was delivered with only power lines and COAX. Newly build houses usually are very efficient in using all the space available, so they lack the small corners and niches where one could easily hide some cables. And last but not least; my house is build from concrete and stone, so no easy drilling. Maybe I should have expected problems, but in 2004 I figured that Wifi and Powerlan would do the trick.

So I currently have the need for four networks:

  • wired LAN for my office computers,
  • over-the-air internet for the laptops and tablets,
  • media streaming for watching the family video’s,
  • digital HDTV streaming.


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JavaFX 2.0 bubblemark – part 2

  • Post category:JavajavafxUI

The first post on the JavaFX 2.0 bubblemark created some feedback, most notably an email from the JavaFX engineering team stating in so many words that JavaFX 2.0 has an issue and that is why it per default is not running on full speed. But the remedy should be the magical “-Djavafx.animation.fullspeed=true” option. So without further due the JavaFX bitmap test was run with that option.

So first here is the total view for all 4 tests (the ‘+’ is the fullspeed option):

And the zoomed-in version:


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JavaFX 2.0 bubblemark

  • Post category:JavajavafxUI

Oracle has released the revamped JavaFX 2.0 on JavaOne 2011. It’s an interesting step which immediately invokes many questions. What is the target audience for JavaFX? Which technology segment does it aim at? What are the chances it will actually claim a piece of that segment? Is it any good at the segment it is aiming at? Only the future will tell the answers to all the questions. But some can be attempted to be answered today.

First of all a short summary of what I believe JavaFX 2.0 is: JavaFX attempts to be a higher performance graphics framework, with a UI layer on top, able to display different types of media.

  • “Higher” means that it is not aiming at high end gaming (for example the recently released Battlefield 3 and Call of Duty Modern Warfare 3), but more at the level of platform games like Mario Bros or the fancier and animated user interfaces that some applications have lately.
  • “Graphics framework” indicates that it is not a UI library in its core (like Swing or SWT), but its designed primarily for drawing, manipulating and animating shapes like circles, rectangles and lines.
  • “UI layer on top” to note that it does come with a good set of UI controls, that are drawn using the graphics framework and thus can easily be made “fancy”.
  • “able to display different types of media” means that there is support for playing audio or video streams.

This kind of framework is commonly known as a RIA, or rich internet application, framework.

Having established the technical intention of JavaFX, the first step would be to see if it is any good at what it’s trying to be. This means bringing out the tame racing driver, aka a common frame of reference. For benchmarking a RIA the unofficial first thing to do is throw the bubblemark test at it. (more…)

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