Also note that no matter where the variable is defined i.e instance(on Heap) or local(on Stack) the object itself will always be on the Heap there is No Stack object.
... JVM's are allowed in theory to allocate objects on the stack in theory in certain specific circumstances ...
"Escape analysis
The
Java language does not offer any way to explicitly allocate an object on the stack, but this fact doesn't prevent JVMs from still using stack allocation where appropriate. JVMs can use a technique called escape analysis, by which they can tell that certain objects remain confined to a single
thread for their entire lifetime, and that lifetime is bounded by the lifetime of a given stack frame. Such objects can be safely allocated on the stack instead of the heap. Even better, for small objects, the JVM can optimize away the allocation entirely and simply hoist the object's fields into registers. "
http://www.ibm.com/developerworks/java/library/j-jtp09275.html
"Eagles may soar but weasels don't get sucked into jet engines" SCJP 1.6, SCWCD 1.4, SCJD 1.5,SCBCD 5