java garbage collection and null reference

Question

In my studying for OCJP I came across the following question:

class CardBoard {
           Short story = 200;
           CardBoard go(CardBoard cb) {
                


        

Answer 1

c3 is not an object. It's a variable referencing null. A variable can't be eligible to GC. Only objects can be eligible to GC.

The objects eligible to GC are the Cardboard which was initially referenced by c1, and the Short instance initially referenced by the CardBoard initially referenced by c1.