How to install Java in Windows
Chances are, there is a copy of Java on any computer you walk up to. According to Sun Microsystems, the company behind Java, it has been installed on more than 800 million computers. There are versions of Java for many operating systems, including Windows, OS X, Linux, and Solaris, just to name a few. You can see if Java is installed on a computer by visiting Javatester.org.
If there is a copy of Java on a computer you own or maintain, it may be old. JavaTester.org not only reports the installed version but gives you some idea of more