Qualified variables for garbage collection in Java

I was preparing for ocpjp, and I was trapped in the following mock exam questions:

Whereas:

3. interface Animal { void makeNoise(); }

4. class Horse implements Animal {
5.     Long weight = 1200L;
6.     public void makeNoise() { System.out.println("whinny"); }
7. }

8. public class Icelandic extends Horse {
9.     public void makeNoise() { System.out.println("vinny"); }

10.    public static void main(String[] args) {
11.        Icelandic i1 = new Icelandic();
12.        Icelandic i2 = new Icelandic();
12.        Icelandic i3 = new Icelandic();
13.        i3 = i1; i1 = i2; i2 = null; i3 = i1;
14.    }
15. }

When line 14 is reached, how many objects qualify for the garbage collector?

A. 0

B. 1

C. 2

D. 3

E. 4

F. 6

Their correct answer is e, four objects, but I'm not sure why From my point of view, I2 and its weight will qualify for garbage collection Maybe I missed something, please advise me

Solution

Let's call Icelandic () on line 11 ICEA, line 12 iceb, and so on

After creation

i1 = IceA
i2 = IceB
i3 = IceC

After I3 = I1

i1 = IceA
i2 = IceB
i3 = IceA

After I1 = I2

i1 = IceB
i2 = IceB
i3 = IceA

After I2 = null

i1 = IceB
i2 = null
i3 = IceA

After I3 = I1

i1 = IceB
i2 = null
i3 = IceB

So only Icelandic () created in line 12 is left Now, each Icelandic () has a long weight, so ICEA and ICEC are not referenced now, which means that four objects (ICEA, icea.weight, ICEC, ICEC. Weight) can be used for GC

Other questions:

>Args is still args. They do not calculate this problem. Out of range > long weight is not statically declared, so each instance of the class has a weight object