Garbage Collection :exam lab

[Sudhakar Duraiswamy]

Hi,


Could some explain me how the answer is Line 10.


Q: After which line only one object is eligible for GC

1.  public class Aegis{
     2.       Aegis ags=null;
     3.       public static void main(String argv[]){
     4.            Aegis a1=new Aegis();
     5.            Aegis a2=new Aegis();
     6.            Aegis a3=new Aegis();
     7.            a1.ags=new Aegis();
     8.            a2.ags=a1.ags;
     9.            a3.ags=a2.ags;
     10.           a1=null;
     11.           a2=null;
     12.           a3=null;
     13.      }
     14. }

Here is my derivation

Situation at Line 9

a1	    a2	    a3
|	    |	    |
|	    |	    |
a4----->a4----->a4

at Line 10

a2           a3
|             |
|             |
null         null

so my answer was Line 11


how is it Line 10
Source :Exam Lab

[Abimaran Kugathasan]

From where the object a4 came?

[Henry Wong]

Sudhakar Duraiswamy wrote:
how is it Line 10
Source :Exam Lab

After line 10 is executed, how do you reach the object that was created on line 4?

Henry

[Sudhakar Duraiswamy]

@Abimaran a4 is the object that was newly created at line 7 . I gave it a name a4 for reference.

@henry:
I didnt understand .Could you please elaborate your question

[Abimaran Kugathasan]

Sudhakar Duraiswamy wrote:@Abimaran a4 is the object that was newly created at line 7 . I gave it a name a4 for reference.

@henry:
I didnt understand .Could you please elaborate your question

Check this figure, I manage to draw it . In the line 10, the object, previously referred by a1, has no reference. So it's eligible for GC

[ravi keshri]

hiiiii sudhakar
i think for any object which is eligible for garbage collection the condition is that there should no refercence varible exist or by any way we cannot access that object.
in your question you can see after line 10 one object is eligible for gc.
thanks......have a good day.

[Faisal A Khan]

Just to elaborate Ravi's point. Please note the object reference contained in a1 has already been copied to the other objects. Hence only a1 is eligible after line 10