是ArrayList.size（）方法中缓存？ [英] Is ArrayList.size() method cached?

问题描述

我想知道，是尺寸（）方法，你可以调用现有的的ArrayList＆LT; T＆GT; 缓存？
抑或是preferable在性能关键code，我只是存储尺寸（）在当地的诠释？

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?

我希望它确实缓存，当你不调用之间添加/删除项目尺寸（）。

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

我说得对不对？

更新结果
我说的不是内联或这样的事情。我只是想知道，如果方法尺寸（）本身内部缓存的价值，或者说，它动态地计算每调用时的时间。

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.

推荐答案

我不认为我会说这是缓存这样 - 但它只是存储在一个领域，所以它的速度不够快，经常致电

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.

太阳JDK实施尺寸（）仅仅是：

The Sun JDK implementation of size() is just:

public int size() {
    return size;
}

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