This page describes the Apple Java Preferences Application.
If you have not yet installed Apple's Java OS X 2012-006 update, then you are still using a version of Apple Java 6 that includes the plug-in and the Java Preferences app. There is an important difference about the installation of Oracle Java (both JRE and JDK) that you should be aware of.
The Applications > Utilities > Java Preferences application is part of Apple's implementation of Java. Once Apple no longer distributes Java as part of their release, the Java Preferences application is retired.
Under Apple's implementation of Java, it was possible to have multiple JREs installed, and the Java Preferences app was used to determine the first compatible version that would be used. The following instructions show how to change the default JRE.
Launch Java Preferences. The Java Preferences window contains a list of installed JREs. Java applications and command line tools use the listed order to determine the first compatible version to use. The Vendor column indicates whether the Java release is supplied by Apple or Oracle. The Version column specifies the version of Java that is installed.
To make JRE 8 the default version of Java, re-order the list by dragging Java SE 8 to the top of the list.
Note that if you install only Oracle Java JRE 8, it will not appear in this list. You must install the full JDK in order for JRE 8 to be listed.