IBM JDK
The ibm centre for java technology provides java developer kit downloads that can be used
to create and test java applets and application on some of today's most popular platforms, including aix, linux, os/390
and z/os, and windows.
http://www-106.ibm.com/developerworks/java/jdk/?dwzone=java
SUN JDK
Java platform, standard edition, one of the most widely available and preferred client and server software platforms, serves as the cornerstone in sun's portfolio of developer products and services. java multiplatform support offers mission-critical java support for heterogeneous computing environments (e.g., solaris, linux).
http://java.sun.com/j2se/