About Java 2 Platform Standard Edition (J2SE) 5.0 Release 1 for Tiger
The Java 2 Platform Standard Edition (J2SE) 5.0 Release 1 software update provides support for cross-platform J2SE 5.0 applications and J2SE 5.0-based applets in Safari on Mac OS X 10.4 "Tiger."
This update does not change the default version of Java on your Mac from Java 1.4.2 to J2SE 5.0, though Java applications that require J2SE 5.0 may specifically request it. You can change the preferred Java version for applications and applets by using the new Java Preferences utility. This utility is installed by the J2SE 5.0 update at /Applications/Utilities/Java/J2SE 5.0/.
Installing J2SE 5.0 Release 1
Get the J2SE 5.0 Update here.
Double-click the "J2SE50Release1.dmg" disk image file that you downloaded, and it will mount to appear as a disk in the Finder.
Open the mounted disk, then double-click the Installer icon.
Follow the onscreen instructions to complete the installation.
Software developers may visit the Java Reference Library for information on this release's features.