List和Set之间的性能和内存分配比较 [英] Performance and Memory allocation comparision between List and Set

问题描述

我想知道List和Set之间在性能，内存分配和可用性方面的比较。

I want to know the comparison between List and Set in terms of performance,memory allocation and usability.

如果我没有保持唯一性的任何要求在对象列表中，既不需要插入顺序来维护，我可以使用ArrayList和SortedSet / HashSet互换吗？
直接使用Collections类而不是列表/集合是好的吗？

If i don't have any requirement of keeping the uniqueness in the list of objects, neither required the insertion order to be maintained, Can I use ArrayList and SortedSet/HashSet interchangeably? Will it be good to directly use Collections class instead of even list/set?

我也没有任何需要列表或设置由java提供的特定函数。
我使用List / Set而不是Array，因为它们可以在没有额外编程的情况下动态增长。

P.S. I also don't have any need for list or set specific functions provided by java. I am using List/Set instead of Array only because they can dynamically grow without extra programming efforts.

推荐答案

你不关心排序，不要删除元素，那么它真的归结为你是否需要在这个数据结构中找到元素，以及你需要这些查找的速度。

If you don't care about the ordering, and don't delete elements, then it really boils down to whether you need to find elements in this data structure, and how fast you need those lookups to be.

在 HashSet 中通过值查找元素是 O（1）。在 ArrayList 中，它是 O（n）。

Finding an element by value in a HashSet is O(1). In an ArrayList, it's O(n).

如果你只是使用容器来存储一堆唯一对象，并在最后（以任何顺序）迭代它们，那么可以争论 ArrayList 是一个更好的选择，因为它更简单，更经济。

If you are only using the container to store a bunch of unique objects, and iterate over them at the end (in any order), then arguably ArrayList is a better choice since it's simpler and more economical.

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