Elektor_Mag_-_January-February_2021

98 January & February 2021 http://www.elektormagazine.com

I also joined the Pi4J-team. Pi4J is a frame-

work and library to combine Java applica-

tions with the full power of the GPIOs of

the Raspberry Pi. This project was started

by Robert Savage, and he was looking for

extra team members to bring this project to

a new generation which fully supports Java

11+ and the Raspberry Pi 4 with Java modules

and an easily extendable architecture. I’m

really excited about the second version of this

framework, which we hope to release soon.

Abate: Let’s return to the book, Getting

Started with Java on the Raspberry Pi. Why

did you write it?

Delporte: When starting the drum booth

project, I had to find out how to use Java on

the Raspberry Pi, how to install the right

version of JavaFX, how to control the GPIO

and an Arduino, etc. That’s when I wrote my

first article [9], which was published in MagPi

(July 2019, Dutch [10] and French [11] edition).

Elektor contacted me and asked if this

could be the subject of a book. As I couldn’t

find a recent one on this topic and Java

had some major changes in the last years,

this question really triggered me and the

next day I started writing. It took me more

than six months and a lot of evening and

nights, but I really had fun while writing

and experimenting. And, of course, I hope

it’s as much fun to read the book and try out

the projects that I included.

Abate: Do you have any advice for engineers

or makers who are thinking about using Java

for their Raspberry Pi-based designs?

Delporte: Try it, really! Java is still one of

the top programming languages world-

wide. Whether you are an experienced

Java developer or starting from scratch,

there is a lot to learn and experiment when

experience with Arduino and Raspberry

Pi. They brought there kits to the club, and

I was really amazed of the power of these

inexpensive boards and what you can

achieve with them combined with small

electronic components.

I was blogging already for some time, but

my first “public” Raspberry Pi-project was

indeed this Pong game that we used on

some activities of the school of my son.

I used Python for the user interface; but

I have to be honest, I didn’t like to code

it very much. For that kind of applica-

tion, I really prefer JavaFX for which there

is even a very nice gaming framework:

FXGL [6].

Abate: Do you have any RPi-based designs

or applications running at home or in your

workspace?

Delporte: I started with Java on the

Raspberry Pi to build a drum booth control-

ler [7] for my son. It’s a touch-screen user

interface to control multiple lights with a

relay-board and LED strips controlled by

Arduino (Figure 3).

This way I learned to use serial communi-

cation between the two boards and I²C to

control the relays. In my book, I extended

this further and used a Mosquitto queue to

exchange messages between more boards

and PCs.

Abate: What else are you working on these

days? New projects, programs, or books?

Delporte: I’m further experimenting with

Java on the Raspberry Pi, of course. I wrote

some more blog posts on this subject and also

experimented with other Java technologies

(Quarkus [8], Spring, GraalVM) and 64-bit

operating systems on the board.

Since I started experimenting with Java
on Raspberry Pi, I got involved in some
open-source projects and discussions, and
that’s a complete new world to me, where
I meet a lot of very bright people who are
also willing to share their knowledge and
experience. Still every day I’m amazed by
the stuff you can learn from these projects
and people. You don’t have to contribute
code, but you can also join such a project
by reviewing pull requests, helping to test
or document the code.

Abate: Are you anti-Python or anti-C? I
assume you aren’t, but I have to ask.

Delporte: Definitely not! I hate haters.
There are no bad programming languages!
I once read a quote which says, “The best
tool for the job is the one you know the
best.” In my case, that’s Java and JavaFX if
I want to make an application with a nice
user interface. But in my book, I also used
Python to control a LED number display
and an Arduino with LED strips.

For each project (Figure 2), you must make
a decision what the best tool, programming
language or framework is. And once you’ve
decided, go for it! Maybe you’ll realize later
you didn’t make the best choice, but at least
you will have learned new things.

Working with Java on the
Raspberry Pi

Abate: You have been blogging about technol-
ogy since 2007. It looks like your first post
about Rapsberry Pi was “Pong on a Raspberry
Pi” [5] (December 2017). Can you tell us about
your first experiences and projects with RPi?
When did you get started with it?

Delporte: When I started with CoderDojo,
there were some coaches who already had

Figure 3: The drum booth controller’s installed components. Figure 4: Rainbow effect selected for LED strips.