This is one of the two successor projects of ruby processing
Currently jruby_art (and jruby) does not work with the Java 9 SDK. Install the 1.8 SDK and then use /usr/libexec/java_home -v 1.8 to get the path for JAVA_HOME:
$ export JAVA_HOME="$(/usr/libexec/java_home -v 1.8)"
This should make the installation and running of the examples possible.
$ k9 --run index.rb