Question

I was wondering, is the size() method that you can call on a existing ArrayList<T> cached?
Or is it preferable in performance critical code that I just store the size() in a local int?

I would expect that it is indeed cached, when you don’t add/remove items between calls to size().

Am I right?

update
I am not talking about inlining or such things. I just want to know if the method size() itself caches the value internally, or that it dynamically computes every time when called.

Answer 1

I don’t think I’d say it’s “cached” as such – but it’s just stored in a field, so it’s fast enough to call frequently.

The Sun JDK implementation of size() is just:

public int size() {
    return size;
}