Java used to be deeply embedded in OS X, but in recent versions of the OS it's an optional install. Here is how to check to see if it is installed, and how to disable or remove it.

This post explains how to install Java or check which version is running on your machine. Install on any OS, and learn about the JDK.

There is, as far as I know, no way to restrict the offline use of Java, that is, Java used by installed applications.