Location of Java 2 SDK

I am trying to install the J2me Wireless Toolkit on a Linux system but the install errors with a

"This application requires Java 2 SDK" message. Please point me to the correct file(s) as the Sun site is not the easist to interpret. I have JRE1.5 currently installed - obviously not an SDK as the install requires.

Regards

[340 byte] By [touchwooda] at [2007-10-3 4:11:14]