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

no, there is no hardware simulation on the JVM.
java bytecode is an intermediate language that when fed to the VEM will be converted to common assembly, stuffed with managed-code stubs, libs loaded, rechecked, optimized and so on until loaded on memory and executed normally on the machine's hardware, you can read and use the system peripherals directly from java, there is no double memory address masking