Which is the most performance efficient implementation for assignCode method from the given options?
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code attribute cannot be changed as Item class doesn’t have setter method for it.
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for (int i = 0; i < itemList.size(); i++) { if(itemList.get(i) != null) { ((Item)itemList.get(i)).code = 50+i; } }
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int i = 0; Item im = null; while (i < itemList.size()) { im = (Item)itemList.get(i); if(im != null) { im.code = 50+i; } i++; }
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int i = 0; Item im = null; Iterator itr = itemList.iterator(); while (itr.hasNext()) { im =(Item) itr.next(); im.code = 50+i; i++; }
Option D uses an Iterator to traverse the list, which avoids repeated get(i) calls and index recalculation. For LinkedList, get(i) is O(n), making B and C O(n²). Iterator provides consistent O(1) traversal regardless of List implementation. Options A, B, C all work but D is most efficient.
Using an Iterator to walk the list is the most robust and efficient choice because it doesn't depend on the underlying List implementation supporting fast random access — get(i) in a loop can degrade to O(n) per call (and O(n^2) overall) for implementations like LinkedList, whereas an iterator always advances in O(1). The indexed for and while loops using get(i) work but are less efficient in general, and the first option is simply false since the code visibly mutates the public code field directly.