Java 中的类型列表与类型 ArrayList [英] Type List vs type ArrayList in Java

问题描述

(1) List<?> myList = new ArrayList<?>();

(2) ArrayList<?> myList = new ArrayList<?>();

我知道通过 (1)，可以交换 List 接口的实现.似乎(1)通常用于应用程序而不管需要(我自己总是使用它).

I understand that with (1), implementations of the List interface can be swapped. It seems that (1) is typically used in an application regardless of need (myself I always use this).

我想知道是否有人使用(2)?

I am wondering if anyone uses (2)?

此外，这种情况多久(我可以举个例子)实际上需要使用(1)而不是(2)(即其中(2)不够......除了编码到界面和最佳实践等)

Also, how often (and can I please get an example) does the situation actually require using (1) over (2) (i.e. where (2) wouldn't suffice..aside coding to interfaces and best practices etc.)

推荐答案

几乎总是 List 优于 ArrayList 因为，例如，List> 可以翻译成LinkedList 不影响代码库的其余部分.

Almost always List is preferred over ArrayList because, for instance, List can be translated into a LinkedList without affecting the rest of the codebase.

如果使用ArrayList 而不是List，则很难将ArrayList 实现更改为LinkedList 实现因为在代码库中使用了 ArrayList 特定方法，这些方法也需要重构.

If one used ArrayList instead of List, it's hard to change the ArrayList implementation into a LinkedList one because ArrayList specific methods have been used in the codebase that would also require restructuring.

您可以阅读List 实现这里.

您可以从 ArrayList 开始，但很快就会发现另一个实现是更合适的选择.

You may start with an ArrayList, but soon after discover that another implementation is the more appropriate choice.

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