clone(): ArrayList.clone() I thought does a shallow copy

Question

ArrayList a=new ArrayList();
a.add(5);
ArrayList b=(ArrayList)a.clone();
a.add(6);
System.out.println(b.t         


        

Answer 1

If it was like you thought, then the clone method would be completely useless, because in that case, the following lines would be equivalent:

ArrayList b = (ArrayList)a.clone();
ArrayList b = a;

Cloning is - like in real world scenarios - a process of creating two entities with exactly the same properties (at the time of the cloning operation).

And as Bozho mentioned - avoid the Java clone() concept. Even it's author mentioned, that it is broken.

This question and it's answers are quite valuable and provide a link to Josh Blochs own comments on his piece of work ;-)