Java platform is a software-only platform that runs on the top of other hardware-based platforms, other platforms are mostly hardware software or hardware only and can be run only on hardware based.

 Programmer can develop Java code on any OS. 

Most of the other platforms do not have this capability.

https://www.geeksforgeeks.org/what-are-the-main-differences-between-the-java-platform-and-other-platforms/#:~:text=Java%20platform%20is%20a%20software,do%20not%20have%20this%20capability.