指定数组列表大小和容量？

Question

I have created an arraylist like this

List<Integer> i = new ArrayList<Integer>(2);

i.add(1);
i.add(2);
i.add(3);
i.add(4);

But I am not getting any exception though i have defined initial capacity as 2 why is not throwing any exception? Does the List grows automatically after it reaches the mentioned capacity??

Answer 1

The initial capacity isn't a limit. It represents how much data can be put into the list before the list has to be reallocated.

Answer 2

You aren't getting an exception because you make assumptions on behavior ... which you didn't bother to cross-check. When code doesn't behave as you expect, far too often your expectations are wrong.

And in such cases, you turn to the Javadoc and find:

Each ArrayList instance has a capacity. The capacity is the size of the array used to store the elements in the list. It is always at least as large as the list size. As elements are added to an ArrayList, its capacity grows automatically.