I am doing a project where I have to develop a Java program that would work platform independently ...

I was wondering, since Java is platform independent itself (the way the JVM and the compiler's developed), do I have to do anything extra as a programmer?

The OS's that I have in mind are Unix, Windows and Mac OS.

Pretender, Wanderer, Dede or someone else ... help me out here! :)

Avoid specific hardware calls and and platform specific capabilties ...

Keep it simple and you'll not run into trouble ...