Garbage Collector doubt (Examlab Diagnostic Test) Q4

[Sridhar Gudipalli]

source: (Examlab Diagnostic Test) Q4

Q. How many objects are eligible for Garbage Collector, after executing the Line-12 of the following program?

   
class A {
	A a;
	public A(A a){
		this.a =a;
	}
	
	public static void main(String args[]){
		A a1=null;
		A a2=new A(new A(null));
		A a3 = new A(a2);
		a1=a3;
		a1.a=new A(null);
		a2.a=null; //Line 12
		System.gc();
	}
}

I am confused to solve this problem. Any clue would be highly appreciated.

[Joshua Antony]

You have to analyse this using pen and paper, find out how many objects are created in total and then check out how many gets derefrenced.
I guess 4 new objects are created in this scenario and finally 1 becomes eligible for GC

Cheers-
Joshua

[Rufat Piriyev]

Sridhar Gudipalli wrote:source: (Examlab Diagnostic Test) Q4

Q. How many objects are eligible for Garbage Collector, after executing the Line-12 of the following program?

   
class A {
	A a;
	public A(A a){
		this.a =a;
	}
	
	public static void main(String args[]){
		A a1=null;
		A a2=new A(new A(null));
		A a3 = new A(a2);
		a1=a3;
		a1.a=new A(null);
		a2.a=null; //Line 12
		System.gc();
	}
}

I am confused to solve this problem. Any clue would be highly appreciated.

I am confused too, but IMHO 0 object ?
There is a scheme but I 'm not sure 100%

[Sridhar Gudipalli]

Rufat Piriyev wrote:
I am confused too, but IMHO 0 object ?
There is a scheme but I 'm not sure 100%

Thanks for trying to solve. But the answer is 1. I tried to draw this object creation. But still not clear with the flow.

[Joshua Antony]

Answer is 1 because a2.a=null frees an object therby making it eligible for GC. I am sure you can find out if you try a bit harder

Cheers-
Joshua

[Sahil Kapoor]

Answer is clearly 1.

a2-->[ Object A1 (IV) ]---->Object A2
a3--->[Object A3 (IV) ]---->Object A1
a1---->Object A3
[Object A3 (IV) ] ---->Object A4
Line12 a2.null cause AI object to be eligible for Garbage Collection.


Note:- [Object A1 (IV) )----> by this link i mean Object A1's Instance Variable(IV) is Pointing to

I have numbered Object A's just to make it bit easier....so A1 A2 A3 and A4 are all Object A.

Thanks !!!