That i don't think is platform  independence. Even if you have 2 or more
different OS on your system, the underlying machine code is the same
since u have 1 processor only. Whether u compile using VC on windows or
gcc on Linux both produce the machine code for the same processor. What
differs are the libraries or other related stuff.

What platform independence means that your code will run on different
processor architectures. i.e. you write your code for your pc and you
can move it to say a sun SPARC machine, or an IBM mainframe, or even a
Nokia mobile phone. It will work since the task of converting byte code
to machine code is of the Java virtual machine.