code attribute cannot be changed as Item class doesn’t have setter method for it.

for (int i = 0; i < itemList.size(); i++) { if(itemList.get(i) != null) { ((Item)itemList.get(i)).code = 50+i; } }

int i = 0; Item im = null; while (i < itemList.size()) { im = (Item)itemList.get(i); if(im != null) { im.code = 50+i; } i++; }

int i = 0; Item im = null; Iterator itr = itemList.iterator(); while (itr.hasNext()) { im =(Item) itr.next(); im.code = 50+i; i++; }