arraylist和linkList区别

For LinkedList<E>

• get(int index) is O(n)
• add(E element) is O(1)
• add(int index, E element) is O(n)
• remove(int index) is O(n)
• Iterator.remove() is O(1) <--- main benefit of LinkedList<E>
• ListIterator.add(E element) is O(1) <--- main benefit of LinkedList<E>

For ArrayList<E>

• get(int index) is O(1) <--- main benefit of ArrayList<E>
• add(E element) is O(1) amortized, but O(n) worst-case since the array must be resized and copied
• add(int index, E element) is O(n - index) amortized, but O(n) worst-case (as above)
• remove(int index) is O(n - index) (i.e. removing last is O(1))
• Iterator.remove() is O(n - index)
• ListIterator.add(E element) is O(n - index)