How much memory do Objects use?

Question

I'm not sure how to ask this, but how does java manage memory usage for multiple objects? Is the memory needed for a classes methods shared amongst the objects of that class, or does each object have memory for it's methods allocated for its use alone?
For example:
class Foo {
   public void doSomething();
}Let's say I have 30 instances of Foo. I can think of 2 options (but I maybe wrong)
Case A: Each instance of Foo has it's own memory allocated for it's own copy of doSomething(), resulting in the total memory
usage of 30 instances of Foo being about 30 times how much memory 1 Foo uses
Case B: Each instance of Foo looks at a common copy of doSomething(), resulting in less memory needed since there is only one copy of doSomething in memory.
If the case is A, Static methods would seem to be potentially more memory efficient. Assuming my thinking is correct(and feel free to say I'm dead wrong), would it not make sense to make as many functions as possible static?

Answer 1

jverd wrote:
Executable code (initializers, methods, constructors): One copy of the bytecodes per ClassLoader that loads the class. Static/non is irrelevant.Seems to answer the question in full.
With reference (no pun intended) to the subject.
Instance variables (non-static member variables): One copy of the variable per instance of the class. Stored on the heap.
Class variables (static member variables): One copy of the variable per ClassLoader that loads the class. Stored on the heap.
Local variables, including parameters: One copy of the variable per invocation of the method.Just to complete the picture a bit (but NOT to contradict earlier comments).
Primitive variables - as above.
Reference variables - as above. Note that method local reference variables are stored on the stack but
any object instances referenced by these are stored on the heap even so.