Java

Installing Sun's JRE/JDK

See http://wiki.serios.net/wiki/Ubuntu_Java_JRE/JDK_installation_with_java-package

Switching java versions

sudo update-alternatives --config java
sudo update-alternatives --config javac
sudo update-alternatives --config javadoc

If other java binaries are required (check in /etc/alternatives), then update the config for them in the same way as above.

Also, update the JAVA_HOME variable in /etc/bash.bashrc