How much additional memory is required when calling the ArrayList.add() method?

Calling ArrayList.add() requires additional memory in two cases:

1. Adding an element: To store the element being added. The size depends on the type of the element.

2. Resizing the internal array: If the current size of the internal array of the ArrayList is insufficient to hold the new element, it is expanded. By default, ArrayList doubles the size of the array (multiplies by 1.5 in recent JDK versions).

   • A new, larger array is created.
   • All existing elements are copied from the old array to the new one.
   • The old array can later be garbage collected.

The additional memory volume during expansion is equal to the size of the new array (approximately 1.5 * current capacity). This does not happen with every call to add(), but only when the current capacity is reached.

Thus, the minimum additional memory is required to store an element, and the maximum is for the new array during expansion.