garbage collection?

[maggie joseph]

class CardBorad{
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);
c1=null;
}
}

here the objects eligible for gc are story and c1...why is cb not eleigible for gc..since after local method completes all objects become eligible for gc and cb is pointing to null???

[W. Joe Smith]

Because cb is just a reference to the same object c2 is pointing to. Since c2 still points to that object, the object is not available for gc.