Any compiler converts source code to machine code in reference with the platform (OS + Hardware) so compiled code becomes platform dependent. But in case of java jvm forms a layer between compiler and the actual platform. so while compiling compiler can't see the original platform but its looking at a dummy platform (JVM) and hence the compiled code formed is no longer in reference of your original platform and is platform independent.

compiled code in java is called Bytecode generated by java compiler (javac).

Java Interpreter(java) is part of JVM.

For different platform JVM Differs.

Other Language:-

source code

compiler (Reference of platform)

compiled code (machine code)