何时在数组列表上使用队列 [英] When to use queue over arraylist

问题描述

在 ArrayList 上使用 Queue 的一个基本参数是 Queue 保证 FIFO 行为.

One basic argument to use a Queue over an ArrayList is that Queue guarantees FIFO behavior.

但是如果我向 ArrayList 添加 10 个元素，然后从第 0 个元素开始迭代这些元素，那么我将按照添加元素的相同顺序检索这些元素.从本质上讲，这保证了 FIFO 行为.

But if I add 10 elements to an ArrayList and then iterate over the elements starting from the 0th element, then I will retrieve the elements in the same order as they were added. So essentially, that guarantees a FIFO behavior.

与传统的 ArrayList 相比，Queue 有什么特别之处?

What is so special about Queue as compared to traditional ArrayList?

推荐答案

如果我给你一个 Queue 实例，那么你就会知道通过迭代调用 remove() 你将按 FIFO 顺序检索元素.如果我给了你一个 ArrayList 实例，那么你就不能做出这样的保证.

If I gave you a Queue instance then you would know that by iteratively calling remove() you would retrieve the elements in FIFO order. If i gave you an ArrayList instance then you can make no such guarantee.

以下代码为例:

        ArrayList<Integer> list = new ArrayList<Integer>();
    list.add(5);
    list.add(4);
    list.add(3);
    list.add(2);
    list.add(1);


    list.set(4,5);
    list.set(3,4);
    list.set(2,3);
    list.set(1,2);
    list.set(0,1);

    System.out.println(list);

如果我现在给你这个列表，那么我从 0 到 4 的迭代你不会得到按 FIFO 顺序的元素.

If I were now to give you this list, then my iterating from 0 to 4 you would not get the elements in FIFO order.

另外，我想说另一个区别是抽象.使用 Queue 实例，您不必担心索引，如果您不需要 ArrayList 必须提供的所有内容，这会使事情更容易考虑.

Also, I would say another difference is abstraction. With a Queue instance you don't have to worry about indexes and this makes things easier to think about if you don't need everything ArrayList has to offer.

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