Processing does not work with the default version of Java installed with Ubuntu (hrrr)
so you must install the one that does: the official Sun JDK 6 (or 7)

1. Download the sun jdk 6 bin from here

2. chmod +x jdk-6u32-linux-x64.bin

3. ./jdk-6u32-linux-x64.bin

4. sudo mv jdk1.6.0_32 /usr/lib/jvm/

5. sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/jdk1.6.0_32/bin/javac 1
   sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/jdk1.6.0_32/bin/java 1
   sudo update-alternatives --install /usr/bin/javaws javaws /usr/lib/jvm/jdk1.6.0_32/bin/javaws 1

6. sudo update-alternatives --config javac
   sudo update-alternatives --config java
   sudo update-alternatives --config javaws

Now you can get processing

1. wget http://processing.googlecode.com/files/processing-1.5.1-linux.tgz

2. tar xzvf processing-1.5.1-linux.tgz

3. cd processing-1.5.1
4. ./processing

Resources

• http://www.devsniper.com/ubuntu-12-04-install-sun-jdk-6-7/
• http://wiki.processing.org/w/Supported_Platforms#Linux
• http://code.google.com/p/processing/issues/detail?id=955
• http://blog.joelotz.net/?p=296
• https://help.ubuntu.com/community/Java