Java 获取二维数组的行数和列数而不对其进行迭代
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/21363104/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
getting rows and columns count of a 2D array without iterating on it
提问by Aniket Thakur
I have a function which takes 2D array. I am wondering if there is anyway to get rows and columns of the 2D array without having to iterate on it. Method signature is not to be changes.
我有一个接受二维数组的函数。我想知道是否有办法获得二维数组的行和列而不必对其进行迭代。方法签名是不可更改的。
Function is inside the ninetyDegRotatorclass.
函数在ninetyDegRotator类里面。
public static int [][] rotate(int [][] matrix){
int [][] rotatedMatrix = new int[4][4];//need actual row n col count here
return rotatedMatrix; //logic
}
And main code is
主要代码是
public static void main(String args[]){
int [][] matrix = new int[][]{
{1,2,3,4},
{5,6,7,8},
{9,0,1,2},
{3,4,5,6}
};
System.out.println("length is " + matrix.length);
int [][] rotatedMatrix = ninetyDegRotator.rotate(matrix);
}
Also matrix.lengthgives me 4. So I guess it is number of rows that it gives meaning number of references in 1D array which themselves contain arrays. So is there a way to get the count without iterating?
也matrix.length给了我4。所以我猜它是行数，它给出了本身包含数组的一维数组中的引用数。那么有没有办法在不迭代的情况下获得计数？
采纳答案by Alnitak
If it's guaranteed that each row has the same length, just use:
如果保证每行具有相同的长度，只需使用：
int rows = matrix.length;
int cols = matrix[0].length; // assuming rows >= 1
(In mathematics this is of course guaranteed, but it's quite possible in most languages to have an array of arrays, where the inner arrays are notall the same length).
（在数学中，这当然是有保证的，但在大多数语言中很可能有一个数组数组，其中内部数组的长度并不完全相同）。
回答by Nikhil Kumar
int row = mat.length;
int col= mat[0].length;
Mostly in array all row has same length. So above solution will work almost every time.
大多数情况下，所有行都在数组中具有相同的长度。所以上述解决方案几乎每次都有效。
