OS within an OS

Would it be possible to make my own mini OS inside a java application? Over the pass few days I've been working on UI stuff and then I realized I basically implemented my own blackbox environment which made me start to think that with a few modifications i could easily make it into a mini OS

>>4

The JVM is just a cross platform abstraction. There is no emulation. An emulator simulates hardware in software. This is really slow, and is only used when needed, like when developing an operating system, or developing an application for a very different type of device, like a mobile phone. Different implementations of the JVM for each platform, with each version providing the same functionality and interface to the java application, is all that is needed here.