I'm confused about the concept of cloning in Array lists. E.g :
Balloon green = new Balloon("Green",new Address("greenState", "greencity")); Balloon green2 = (Balloon)green.clone(); green.setColor("NewGreen"); System.out.println(green); System.out.println(green2);//color not affected in copy as color is of String type. //Immutable objects are not shallow copied. green.getAddress().state="helloState"; System.out.println(green); System.out.println(green2);//Address does get affected Output:-
Balloon[color = NewGreen Address = Address {state = greenState, city = greencity}]
Balloon[color = Green Address = Address {state = greenState, city = greencity}]
Balloon[color = NewGreen Address = Address {state = helloState, city = greencity}]
Balloon[color = Green Address = Address {state = helloState, city = greencity}]
So this I'm clear. But now lets take array lists.
Balloon red = new Balloon("Red",new Address("redState", "redCity")); Balloon blue = new Balloon("Blue",new Address("blueState", "blueCity")); Balloon yellow = new Balloon("yellow",new Address("yellowState", "yellowCity")); ArrayList<Balloon> list = new ArrayList<>(); list.add(red); list.add(blue); list.add(yellow); ArrayList<Balloon> listCopy = (ArrayList<Balloon>)list.clone(); Balloon green = new Balloon("Green",new Address("greenState", "greencity")); list.get(1).setColor("color"); list.add(green); System.out.println(list); System.out.println(listCopy); Output:-
[Balloon[color = Red Address = Address {state = redState, city = redCity}], Balloon[color = color Address = Address {state = blueState, city = blueCity}], Balloon[color = yellow Address = Address {state = yellowState, city = yellowCity}], Balloon[color = Green Address = Address {state = greenState, city = greencity}]],
[Balloon[color = Red Address = Address {state = redState, city = redCity}], Balloon[color = color Address = Address {state = blueState, city = blueCity}], Balloon[color = yellow Address = Address {state = yellowState, city = yellowCity}]]
So in the above output, changing the color of a balloon in a list affects the copy as well. But adding a new element does not reflect in the copy.
Can someone explain this?
Based on luk2302's answer, the following visualization explains what is going on:
list object listCopy |___ red ___| |___ blue ___| |___ yellow ___| list.add(green); list object listCopy |___ red ___| |___ blue ___| |___ yellow ___| |___ green list.remove(blue); list object listCopy |___ red ___| blue ___| |___ yellow ___| |___ green 
