Processing is an open source programming language (processing.org) and environment for people who want to create images, animations, and interactions.

This is how to install it on your Raspberry PI:

• install the java 6 sdk
  sudo apt-get install librxtx-java openjdk-6-jdk
• download and unzip the Linux (x86) version of Processing 1.5.1 to the /home/pi directory
  http://processing.googlecode.com/files/processing-1.5.1-linux.tgz
• change your working directory to /home/pi/processing-1.5.1 before executing the following commands
  cd /home/pi/processing-1.5.1
• delete the directory /home/pi/processing-1.5.1/java
  sudo rm -rf java
• create a symbolic link to the system’s java SDK
  sudo ln -s /usr/lib/jvm/java-6-openjdk-armhf java
• delete the RXTXcomm.jar file
  sudo rm modes/java/libraries/serial/library/RXTXcomm.jar
• copy the system’s RXTXcomm.jar file
  cp /usr/share/java/RXTXcomm.jar modes/java/libraries/serial/library/
• fire up Processing from the file manager (or LZTerminal)
  (ignore the ‘Not found of this java VM‘ warning!)

That’s it!