Developing Algorithms Using ArrayLists

AP Computer Science A· difficulty 3/5

ArrayList<Integer> list = new ArrayList<>();
list.add(1); list.add(2); list.add(3);
for (Integer x : list) {
  if (x == 2) list.remove(x);
}

What happens at runtime?

  • A

    Prints nothing

  • B

    Removes 2 successfully

  • C

    ConcurrentModificationException

    check_circle
  • D

    NullPointerException

Explanation

Modifying a list during enhanced-for iteration triggers ConcurrentModificationException.

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