Recommended Setup For PiCrate

Raspbian Stretch Release

The installed Oracle JDK8 probably works best, you can use the stock OpenJDK8 from Debian distribution.

sudo apt-get install openjdk-8-jdk

Raspbian Buster Release

As of writing java does not come pre-installed with Buster, we strongly recommend that you install stock OpenJDK8 distribution.

sudo apt-get install openjdk-8-jdk

You should avoid installing the default openjdk-11-jdk, since it probably wont perform as well, and lead to complications (lots of warning messages etc). If you still want to use openjdk11, it is recommended that you install the jruby-launcher gem.

Oracle jdk8 for Arm

Is still available for personal use, but it is a bit of hassle to install:-

  1. download
  2. Untar to say /opt folder
  cd /opt
  sudo tar xzvf ~/Downloads/*.tar.gz
  1. Install and configure using update-alternatives
  sudo update-alternatives --install /usr/bin/java java /opt/jdk1.8.0_231/jre/bin/jar 100
  sudo update-alternatives --install /usr/bin/javac javac /opt/jdk1.8.0_231/bin/javac 100
  sudo update-alternatives --install /usr/bin/jar jar /opt/jdk1.8.0_231/bin/jar 100

configure

  sudo update-alternatives --config java
  sudo update-alternatives --config javac
  sudo update-alternatives --config jar

edit ~/.profile

  export JAVA_HOME=/opt/jdk1.8.0_231

install jruby-launcher gem

  sudo jgem install jruby-launcher

Building native extensions. This could take a while... Successfully installed jruby-launcher-1.1.10-java 1 gem installed