I.e., in
class A { public String s; }
and
A a1 = new A(); a1.s = \"bla\"; A a2 = new A(); a2.s = a1.s; a1 = null;
Since A has only a reference to s, a2.s pointing to a1.s would not affect a1's garbage collection.
A
s
a2.s
a1.s
a1
i.e a1 is eligible for GC, but the object referred to by a2.s (or a1.s) will not be eligible for GC.