原始数据类型和包装数据类型的用法有什么区别，包装数据类型的需求是什么? [英] What is the difference in usage of primitive and wrapper data type and what is the need of wrapper data type?

问题描述

我在网上到处搜索，但所有的答案都只是差异而已.我知道区别，但我不明白它们的应用程序的区别.

I searched it all over the web, but all the answers just consisted of the difference. I know the difference, but I don't understand the difference in their applications.

例如，假设我们必须取两个浮点值，如果我们使用double，我们可以很容易地使用a==b进行比较，而如果我们使用Double，我们将不得不使用a.equals(b).

For example, suppose we have to take two floating values, if we use double, we can easily compare using a==b, whereas if we use Double, we will have to use a.equals(b).

推荐答案

幕后还有更多.原因之一是 Collections API 是如何用 Java 开发的...

There is more than that behind the scenes. One of the reasons is how the Collections API is developed in Java...

考虑到你不能做这样的事情:

Consider that you just can not do anything like:

List<int> myList 

在Java中.您将需要包装器

in Java. You will need the wrapper for that

List<Integer> myList 

因为集合适用于对象而不是基元.

because the Collections work with objects and not primitives.

另一方面，包装器是为开发人员提供一组很好的方法/常量的对象，它们使某些操作更快更容易"，例如:

On the other hand, wrappers are objects that offer the developers a nice group of methods/constants that make "faster and easier" some operations like:

int x = 17;

现在，感谢您可以使用包装器:

Now, thanks to the wrapper you can do:

String pars= Integer.toBinaryString(x);
pars= Integer.toHexString(x);
Integer.MAX_VALUE;
Integer.highestOneBit(x);

没有它，你会感到脖子疼，因为原始的 x 对你做这件事没有多大帮助.

Without that you will get a pain in the neck, since the primitive x has not much helpful for you to do that.

这篇关于原始数据类型和包装数据类型的用法有什么区别，包装数据类型的需求是什么?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！