Raspbian Buster installs OpenJDK11 (hard float) and that is just fine, if you have more that one version of java installed you could use update-alternatives tool to manage their use. NB: Will not work with OpenJDK-8.

Then install JRuby see jruby.

jgem install picrate

For a first install:-

picrate --install # no args, install samples and geany config
# or
picrate -i Samples # to omit geany config

This installs example sketches in ~/sample_sketches and ties them into a geany project picrate.geany. It should also be possible to run sketches from the geany ide.

Install processing libraries

picrate -i Sound
picrate -i video # install beta verion of vanilla video for now

To create a template sketch from the command line:-

picrate -c my_sketch 600 400

creates file my_sketch.rb

#!/usr/bin/env jruby
# frozen_string_literal: false
require 'picrate'

class MySketch < Processing::App
  def settings
    size 200, 200

  def setup
    sketch_title 'My Sketch'

  def draw


Edit in vim (at command line) or geany (gui), you may need to install vim

vim my_sketch.rb
:!jruby % # from vim runs the sketch

To run sketches from command line:-

jruby my_sketch.rb

Or even chmod +x my_sketch.rb to make an executable script.

See editors geany, for how to run sketches from a gui.

Circle Collision Sketch Running on RaspberryPI