What does "Primitive values do not share state with other primitive values" mean?

Question

Section 4.2 of the Java Language Specification states that, "Primitive values do not share state with other primitive values". What exactly does this mean?

Answer 1

This means that each value of primitive type occupies its own space in memory, representing a state which cannot be shared with other values. In other words, you cannot change the state of a variable or a field of a primitive type in any way other than assigning it, directly or through a compound assignment operator.

This is in contrast with reference types, which may or may not share state by "pointing" to the same object. You can change a reference object by manipulating it through a different variable.

Answer 2

I suspect it's drawing a distinction between primitives and reference types - where in the latter case, two values (references) can both refer to the same object. If you have two primitive variables, there is nothing you can do to one that would affect the other.

It's not terribly clearly worded though, as even with reference types the values themselves (the references) don't share state; in particular, changing the value of one reference type variable doesn't change the value of another variable... it's the state of the object itself which is sort of shared "via" variables with the same value.