I was just looking in the VM spec if a increment operation on an integer is atomic or not. My opinion it has to be in the case of class members as the increment is surrounded by getfield/putfield instructions.
Accessing an "int" is atomic. Accessing a "long" is not. This is all from memory, which might fail, of course ... so let me see if I can dig up a reference...
There! Doug Lea, "Concurrent Programming in Java", p. 63:
"The Java language specification allows access and storage of [variables of type double and long] (but not those of other scalar types) to be non-atomic."
Ugo
