Java 数组:属性大小? [英] Java array: Attribute size?

问题描述

我在 Stack Overflow 上找到了这个答案:

<块引用><块引用>

length 是常数，用于找出数组存储容量而不是数组中元素的数量

示例:

int a[] = new int[5]

a.length 总是返回 5，称为一个的容量数组，所以长度总是返回容量.但是

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数组中元素的个数称为大小"

示例:

int a[] = new int[5][0] = 10

将导致 a.size = 1 和 a.length = 5.

size() 适用于集合，length 适用于 java 中的数组

(尺寸和长度方法的区别? , 2017-09-06)

由于这个答案收到了五个赞成票，我认为这是正确的.但是实际上 Java 中没有数组的 size 属性.我知道 ArrayLists 有一个方法.但是，如果使用普通数组，如何 a.size 等于 1?我错过了什么吗?

解决方案

你是对的，答案是错误的:Java 数组没有 .size 属性，只有 .length.

为了让答案的作者受益匪浅，我怀疑他们正试图解释 ArrayList 如何在内部使用数组.

ArrayList 实际上通常在元素数组旁边有一个 .size 成员:

class ArrayList实现 ... {私有 T[] 元素；私有整数大小；...}

I found this answer on Stack Overflow:

length is constant which is used to find out the array storing capacity not the number of elements in the array

Example:

int a[] = new int[5]

a.length always returns 5 which is called the capacity of an array, so length always returns the CAPACITY. but

"number of elements in the array is called size"

Example:

int a[] = new int[5]
a[0] = 10

Will result in a.size = 1 and a.length = 5.

size() works with collection, length works with arrays in java

(Difference between size and length methods? , 2017-09-06)

As this answer received five upvotes I thought it is correct. But there is actually no size attribute for arrays in Java. I know there's a method for ArrayLists. However, how can a.size be equal to one if normal arrays are used? Am I missing something?

解决方案

You are correct and the answer is mistaken: Java arrays don't have a .size attribute, only .length.

To give the answer's author the benefit of the doubt, I suspect they are trying to explain how an array gets used internally by an ArrayList.

An ArrayList does in fact typically have a .size member alongside the element array:

class ArrayList<T> implements ... {
    private T[] elements;
    private int size;
    ...
}

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