Java is Sun’s Object-Oriented language which claims to be able to “write once, run anywhere”. While this is not too far from the truth, there are a few things to be wary of:

• The portability of Java is reliant on how good the implementation of the Java Virtual Machine (VM) is on the target platform. For example, Java VM implementations on GNU/Linux are still not particularly mature.
• It can be a real bother to download a VM, which will often discourage people from running Java programs if their operating system of choice doesn’t already come pre-installed with a Java VM (this means users of Windows XP, GNU/Linux, *BSD and many others).
• Well written, standards-compliant C code is often as portable as Java, without the overheads of a VM associated with it.

There are some great Java tutorials, plus Java VM downloads at java.sun.com

1. C/C++
2. Java
3. Standard ML, Haskell and other Functional Languages