Java's automatic memory management is the main reason that prevents Java from being used in hard real-time environments. We present the garbage collection mechanism that is used by the Jamaica Virtual Machine, an implementation of the Java Virtual Machine Specification. This mechanism differs significantly from existing implementations in the way threads are implemented, root references are found and in the object layout that is used. The implementation provides hard real-time guarantees while it allows unrestricted use of the Java language. Even dynamic allocation of normal garbage collected Java objects is possible with hard real-time guarantees.