as .class file is executable in any OS with the help of JVM( Java Virtual Machine ), hence Java is called as platform independent.
JVM Software is platform dependent.
a seperate version of JVM software is introduced for every OS.
as .exe (executable) are executable in any OS with the help of a CLR (Common Language Runtime).
hence .Net is platform independent.
for every OS a seperate version of CLR is available, hence CLR is Platform dependent.
.Net is partially Platform Independent Technology
as of now CLR softwares are not yet developed for DOS and Win 95.