Set default java on Ubuntu

$JAVA_VERSION = where java is installed (/usr/lib/jvm/java-1.5.0-sun)
sudo update-java-alternative -s $JAVA_VERSION

java version "1.5.0_18"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_18-b02)
Java HotSpot(TM) Server VM (build 1.5.0_18-b02, mixed mode)