How do I set JAVA environment variables system wide?

Question

I work as java/j2ee application developer so kindly tell me how to set JAVA_HOME, JRE_HOME, CLASSPATH so that I may use Tomcat, Mysql ,java all together in Terminal.

I may be using all together in a pure CLI server environment, or in a GUI desktop environment.

Answer 1

Using 12.04, placing the information in /etc/environment worked for me:

tku@buster:~$ cat /etc/environment 
PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games"
[...]
LC_MEASUREMENT="de_DE.UTF-8"
JAVA_HOME=/home/tku/work/jdk1.7.0_05