ArrayList

ArrayList provides a growable array implementation of a List.

Advantages:

• get and set are O(1)

• add and remove at the end are O(1), so an ArrayList makes a good implementation of a stack.

Disadvantages:

• add and remove are O(n) for random positions: the rest of the list has to be moved down to make room.

• contains is O(n). contains uses the .equals() method of the contents type.

• Some space in the array is wasted, O(n), because the array grows by a factor of 3/2 each time it is expanded.

• clear is O(n), because clear replaces all existing entries with null to allow those items to possibly be garbage collected.