Most Java 2 Platform Standard Edition have an internal code or project name, as listed below. Starting with Tiger, each version has two version numbers: an internal number, such as 1.5.0, and an external number, such as 5.0.
JDK 1.1.4 Sparkler Sept 12, 1997
JDK 1.1.5 Pumpkin Dec 3, 1997
JDK 1.1.6 Abigail April 24, 1998
JDK 1.1.7 Brutus Sept 28, 1998
JDK 1.1.8 Chelsea April 8, 1999
J2SE 1.2 Playground Dec 4, 1998
J2SE 1.2.1 (none) March 30, 1999
J2SE 1.2.2 Cricket July 8, 1999
J2SE 1.3 Kestrel May 8, 2000
J2SE 1.3.1 Ladybird May 17, 2001
J2SE 1.4.0 Merlin Feb 13, 2002
J2SE 1.4.1 Hopper Sept 16, 2002
J2SE 1.4.2 Mantis June 26, 2003
J2SE 5.0 (1.5.0) Tiger Sept 29, 2004
Future Releases
J2SE 6.0 (1.6.0) Mustang Not yet released
J2SE 7.0 (1.7.0) Dolphin Not yet released