I have a pet C++ framework that gives a lot useful classes (provided you want to do game/graphics type stuff, play with threads etc) but nothing like the featureset offered by java's runtime.
The problem you have is that java has a fair few syntatical differences from C++ that would make any such project impossible as well as keywords and their expected behaviours. There's no final, abstract, synchronized, implements, interface, import, export, extends etc and even though the behaviour of these can often be implemented, you won't get that implementation into a simple #define'd keyword that makes your source appear similar to the equivalent java source.
Furthermore, java uses garbage collection, C++ doesn't and writing a GC implementation on a system where your classes might have to do low level work (eg locking hardware resources etc), GC becomes extremely tricky to implement.
There are a great many more differences too, far to many to detail here.
