ArrayList: how does the size increase?

Question

I have a basic question on Java ArrayList.

When ArrayList is declared and initialized using the default constructor, memory space for 10 el

Answer 1

Typically, the memory for ArrayList type containers is increased by doubling it. Thus, if you initially had space for 10 items and you added 10, the eleventh item will be added to a new (internal) array of 20 items. The reason for this is that the incremental cost of adding items is reduced from O(n^2) if the array had been incremented in fixed size increments to a nice O(n) when doubling the size each time the internal array is full.