The platform supporting JVM

Java was claimed to be "Once write, execute everywhere", but I wonder is it really everywhere?

The execution of java program relies on the JVM, and I don't know how many operating systems support JVM.

I went to a oracle(previously 开发者_如何学Csun) website to check for the specification of Java, it only have Windows, Linux and Solaris. Is that all? I've never heard people execute Java in VMS system. However, I don't this is the list, it doesn't have AIX, which I am sure it can run java program.

Oracle does not implement the JVM for all possible operating systems themself. Oracle has a JVM for Windows, Linux and Solaris but for other operating systems you have to go to the manufacturer of the operating system. HP has a JVM implementation for HP-UX, and IBM has a JVM implementation for AIX.

Until recently Apple had their own version of the JVM for Mac OS X but they are now working together with Oracle so that in the future Oracle will maintain the JVM for Mac OS X.

A few years ago I worked on a project where we used Java on OpenVMS, but it was poorly supported and buggy, and then we switched to Red Hat Enterprise Linux which worked much better and faster.

WORA really means write once, run anywhere that has a JVM implementation. Here's a list of known implementations.

(OpenVMS is listed as a proprietary implementation on that page, and seems be be available here)