- 1.0, 1.1, 1.2, 1.3, 1.4 and then version 1.5 which Sun decided to rename version 5. Latest is version 6. Version 7 is coming soon (2010).
- All very compatible but 1.2 was a major step from 1.1 with new way of doing graphics and new GUI classes (Swing and JFC)
- Versions 1.2 onwards were all, confusingly, called Java 2 but now it is clearer with Java 5, 6, etc
- Each version has several intermediate updates. We are now (July 2010) on Java 6 update 20.
Some further abbreviations to note:
- J2SE = Java 2 Standard Edition, now called Java SE
- J2EE = Java 2 Enterprise Edition - more classes, especially for transactional web servers, now called Java EE
- J2ME = Java 2 Micro Edition, for embedded applications (now Java ME)