原始类型和包装类之间的主要区别是什么？ [英] What is the main difference between primitive type and wrapper class?

问题描述

这两行之间有什么区别？

What is the difference between these two lines?

    int pInt = 500;

和

    Integer wInt = new Integer(pInt);

或

    Integer wInt = new Integer(500);

推荐答案

无。

这是完全相同的事情。在第一种情况下，你只有一个补充变量。

That's the exact same thing. In the first case you just have a supplementary variable.

注意 autoboxing 你很少需要同时拥有 int 和 Integer 变量。所以对于大多数情况来说这就够了：

Note that with autoboxing you rarely need to have both an int and an Integer variables. So for most cases this would be enough :

int pInt = 500;

整数有用的主要情况是区分变量未知的情况（即 null ）：

The main case where the Integer would be useful is to distinguish the case where the variable is not known (ie null) :

Integer i = null; // possible
int i = null; // not possible because only Object variables can be null

但是不要保留两个变量，一个是够了。

But don't keep two variables, one is enough.

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