Install Sun J2SE Development Kit 6.0 (JDK 6.0)

If you are using earlier versions of Ubuntu than Natty Narwhal, you can install Sun Java 6 simply with an apt-get command:

  sudo apt-get install sun-java6-jdk

If you are running a more recent version of Ubuntu such as Natty, you will find the above command fails unless you have the partner repositories enabled in your /etc/apt/sources.list. You open this file (you must have root access to do so), and un-comment the following line by removing the '#':

  deb http://archive.canonical.com/ubuntu natty partner

After you have saved the above change, then you may run the apt-get install command mentioned above after you have propagated the update to the system:

  sudo apt-get update
  sudo apt-get install sun-java6-jdk

and then optionally set the default version in your system with

  sudo update-java-alternatives

Alternatively, you can download the latest Java from Sun directly .

Check Your Installation

Make sure that the JAVA_HOME environment variable is pointing to the directory where you installed the JDK.

If using the "apt-get install" method for Ubuntu described above combined with the update-java-alternatives command, you should already have this variable set.