for循环如何在java中创建使用2D数组的方法

Question

我想创建一个计算次数的方法 二维数组中出现一个数字。 用于循环

Answer 1

   //method to count your number of Occurrences in Your 2-D Array.    
private int getAllOccurence(int [] arr, int yourNumberToSearch){ 
 int count = 0;
for (int[] row : arr) {      //loop will able to get all Rows

    for (int value : row) {      //loop enables you to get each values of each Row.

       // This if Statement will check wheather Your Number exists in array or not
        if(value == yourNumberToSearch) 
              count++; //count increase each times by one If Number exists in a array.
    }
  }
  return count;
}

Here You may try this. You will get Your Answer.

Answer 2

如果需要具有不同行数的值的2D数组，则可以像int[][] matrix = new int[10][10];一样声明2D数组，而不是必须自己创建每一行：

int [][] matrix = new int[10][];
matrix[0] = new int[10];
matrix[1] = new int[20];
//...

要在matrix上迭代，您需要

for (int[] row : matrix) {
    for (int value : row) {
        sum += value;
    }
}