什么是一个空数组和空数组之间的区别？ [英] What is the difference between a null array and an empty array?

问题描述

如果一个int数组中的单个元素不被初始化，什么是默认存储在其中？我似乎发现有类似空数组或一个空数组。有什么区别，哪一个适用于我的第一个问题？

If the individual elements of an int array are not initialized, what is stored in them by default? I apparently found that there is something like an empty array or a null array. What is the difference, and which one applies to my first question?

推荐答案

从技术上讲，有作为的空数组的没有这样的事;但因为数组是对象，数组类型是引用类型（即：数组变量牵住的引用的到阵列），这意味着数组变量可以是空，而不是实际指向数组：

Technically speaking, there's no such thing as a null array; but since arrays are objects, array types are reference types (that is: array variables just hold references to arrays), and this means that an array variable can be null rather than actually pointing to an array:

int[] notAnArray = null;

这是空的数组零长度的数组;它没有元素：

An empty array is an array of length zero; it has no elements:

int[] emptyArray = new int[0];

（可以的从不的有元素，因为它的创建后数组的长度不会改变）。

(and can never have elements, because an array's length never changes after it's created).

当你创建的不的没有为它的元素指定值-empty阵列，它们默认为零样值＆MDASH; 0 为一个整数数组，空为对象类型等的数组;所以，这样的：

When you create a non-empty array without specifying values for its elements, they default to zero-like values — 0 for an integer array, null for an array of an object type, etc.; so, this:

int[] arrayOfThreeZeroes = new int[3];

是相同的，因为这

is the same as this:

int[] arrayOfThreeZeroes = { 0, 0, 0 };

（尽管这些值可以重新之后分配;数组的长度不能改变，但它的内容可以改变）。

(though these values can be re-assigned afterward; the array's length cannot change, but its elements can change).

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