（int [] []）的方法是什么意思？ [英] What does a method with (int[] []) mean?

问题描述

我们给出了一些代码片段来查看并弄清楚代码会做什么/将要做什么。

We are given some code snippets to look at and figure out what the code does/will do.

我理解使用数组的方法和方法但我从未见过 methodName（int [] [] m）有两个 [] []

I understand methods and methods with arrays but I have never seen methodName(int[][] m) with two [][]

这是什么意思？数组中的数组？

What does this mean? an array within an array?

推荐答案

int [] [] in方法签名是指双整数数组。您可以将双整数数组视为 int 值的矩阵。

int[][] in the method signature refers to a double array of integers. You can think of a double integer array as being a matrix of int values.

以您的示例2D数组为例：

Taking your example 2D array:

int[][] in = {{2, 0, 2}, {3, 1, 2}, {1, 8, 4}};

此数组具有以下属性：

System.out.println(in.length);     // prints 3 (number of arrays inside 'in')
System.out.println(in[0].length);  // prints 3 (number of ints in first array)
System.out.println(in[1].length);  // also prints 3 (number of ints in second array)

这是一个视觉效果，向您展示如何访问此数组有效：

Here is a visual to show you how accessing this array works:

int a = 1;
int b = 0;

然后在[a] [b] ==中的 [1] [ 0] == 3 ：

Then in[a][b] == in[1][0] == 3:

 2 0 2
{3 1 2} <-- a = 1 (second subarray)
 1 8 4

{3 1 2}
 ^-- b = 0 (first element in that subarray)

第一个索引 a 选择子阵列，索引 b 选择子数组中的元素。

The first index a chooses the subarray, and the index b chooses the element inside the subarray.

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