GC question (K&B SCJP 6)

[Sajesh Adulkar]

I need help to understand why object c3 and its Wrapper object will not be eligible for GC in the following question:

class CardBoard {
Short story = 200;
CardBoard go(CardBoard cb) {
cb = null;
return cb;
}
public static void main(String args[]) {
CardBoard c1 = new CardBoard();
CardBoard c2 = new CardBoard();
CardBoard c3 = c1.go(c2);
//System.out.println(c3);
//System.out.println(c3.story);
c1 = null;
}
}

c3 is indeed set to null so why is it not eligible? (As I understand c2 is not eligible because of return cb; in go()...right?)

[karthick chinnathambi]

To make it Simple...

Your Question's Equivalent one is

class CardBoad
{
  public static void main(String... a)
  { 
      CardBoad c2 = new CardBoad();
       c2 = null;
      CardBoad c3 = c2;
     
  }
}

In the above code as far as i know "c3 is Garbage Collectible ".


only if you do...

class CardBoad
{
  public static void main(String... a)
  { 
      CardBoad c2 = new CardBoad();      
      CardBoad c3 = c2;
       c2 = null;     
  }
}

Then C3 is NOT garbage Collectible

[Sajesh Adulkar]

Thank you, your explanation clarifies what is happening.