why and how Java is platform independent?

Question

as it's clear that since Java is platform independent, it is portable etc...But how come it's code runs on every manufactured micro processor independently without Java compiler?

Answer 1

Java on its own is not very effective. It uses native code like c or c++. This native code is switched in the diffrent versions like Windows Linux and Mac.
Socket can exist on diffrent OSs.

Answer 2

it need the jre (java runtime environment)
which includes jvm (java virtual machine)
to run the code which mean java need a virtual machine to run in every platform.