Yesterday, Apple released Java 2 Platform Standard Edition (J2SE) 5.0 Release 3. It's in Software Update, and you can read more about it (and find a download link) on Apple's About the Java 2 ... Release page. If you're like me, you might be slightly confused by the version number -- it seemingly jumps the Java version from 1.4.2 to 5.0, which is quite the move. In addition, unlike prior Java updates, this one doens't replace the 1.4.2 version; it's installed right next to it.
To help clarify the situation, macosxhints forum moderator hayne has put together a nice write-up that explains what's up with the version number, why two versions are installed, and how to put the new version to use.
Here's a summary of the topics he covers:
- The update (which is only available on Tiger) installs Java 5 (which is also known as Java 1.5)
- The default version of Java remains as Java 1.4 even after the update. Thus it should be quite safe to install this update since by default it makes no change to the Java environment.
- You can change the version of Java to be used by certain Java programs/applets by using the new Java Preferences app, which is found in the Java/J2SE 5.0 folder, within the /Applications/Utilities folder.
- Contrary to what you may have read elsewhere, you should not modify anything (e.g. symbolic links) in the /System area of OS X to change the default to be Java 5.

