Apple's Developer technote here:
Explains what are all the Mac OS X releases for Java, and how to determine if you have the that version. If you don't check Apple - Support - Downloads to see if you can run that update on your machine.
Note, starting with Mac OS X 10.7, Oracle at http://www.java.com/ maintained Java. Use that link to verify your Java version if your operating system is more current than 10.7.