可以存储在 HashMap 中的键(对象)数量的理论限制?

问题描述

对于可以存储在 HashMap 中的键条目的数量是否有理论上的限制，或者最大值是否完全取决于可用的堆内存?

Is there a theoretical limit for the number of key entries that can be stored in a HashMap or does the maximum purely depend on the heap memory available?

另外，哪种数据结构最适合存储大量对象(比如几十万个对象)?

Also, which data structure is the best to store a very large number of objects (say several hundred thousand objects)?

推荐答案

查看该类的文档，我会说理论上的限制是 Integer.MAX_VALUE (2-1 = 2147483647) 个元素.

Looking at the documentation of that class, I would say that the theoretical limit is Integer.MAX_VALUE (2-1 = 2147483647) elements.

这是因为要正确实现这个类，size() 方法必须返回一个 int 表示键/值对的数量.

This is because to properly implement this class, the size() method is obliged to return an int representing the number of key/value pairs.

来自 的文档HashMap.size()

返回:此映射中键值映射的数量

注意:这个问题与一个列表最多可以容纳多少数据非常相似.

Note: This question is very similar to How many data a list can hold at the maximum.

哪种数据结构最适合存储大量对象(比如几十万个对象)?

我想说这取决于您需要存储什么以及您需要什么类型的访问权限.所有内置集合可能都针对大批量进行了优化.

I would say it depends on what you need to store and what type of access you require. All built in collections are probably well optimized for large quantities.

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