java如何创建具有用户定义维度的矩阵，并使用从上到下、从左到右的递增值填充它？

Question

我正在练习Java，我得到了这个，我不知道在哪里以及如何继续：

• Creates a matrix with user-defined dimensions.
• Fills the matrix with increasing values from top to bottom, left to right.
• Print the status of the matrix.

我必须达到的结果应该是这样的5x5：

0  5  10  15  20
1  6  11  16  21
2  7  12  17  22
3  8  13  18  23
4  9  14  19  24

或者这个7x2：

0  7
1  8
2  9
3  10
4  11
5  12
6  13

这就是我所做的：

public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    int count = 0;

    System.out.print("Insert rows [i] : ");
    int i = in.nextInt();
    in.nextLine();

    System.out.println("Insert columns [j] : ");
    int j = in.nextInt();
    in.nextLine();

    int[][] matrix = new int[i][j];
    for (int k = 0; k < matrix.length; k++) {
        for (int l = 0; l < matrix[i].length; l++) {
            matrix[i][j] = count;
            count++;
        }
    }
}

Answer 1

如果你理解nested loops是如何工作的，这并不困难。在内部循环中，可以从等于行索引的值开始，并在内部循环的每次迭代中按行数递增该值

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        System.out.print("Enter the number of rows: ");
        int rows = in.nextInt();

        System.out.print("Enter the number of columns: ");
        int cols = in.nextInt();

        int[][] matrix = new int[rows][cols];

        // Fill the array
        for (int i = 0; i < matrix.length; i++) {
            for (int j = 0, value = i; j < matrix[i].length; j++, value += rows) {
                matrix[i][j] = value;
            }
        }

        // Display the matrix
        for (int i = 0; i < matrix.length; i++) {
            for (int j = 0; j < matrix[i].length; j++) {
                System.out.print(matrix[i][j] + "\t");
            }
            System.out.println();
        }
    }
}

运行示例：

Enter the number of rows: 5
Enter the number of columns: 5
0   5   10  15  20  
1   6   11  16  21  
2   7   12  17  22  
3   8   13  18  23  
4   9   14  19  24  

另一个示例运行：

Enter the number of rows: 7
Enter the number of columns: 2
0   7   
1   8   
2   9   
3   10  
4   11  
5   12  
6   13  

Answer 2

您可以使用流中的流来填充这样的数组：

int m = 5;
int n = 4;
int[][] arr = new int[m][n];
IntStream.range(0, m).forEach(i ->
        IntStream.range(0, n).forEach(j ->
                arr[i][j] = i + j * m));

Arrays.stream(arr).map(Arrays::toString).forEach(System.out::println);
//[0, 5, 10, 15]
//[1, 6, 11, 16]
//[2, 7, 12, 17]
//[3, 8, 13, 18]
//[4, 9, 14, 19]

---

或者您可以在循环中使用循环：

int m = 7;
int n = 2;
int[][] arr = new int[m][n];
for (int i = 0; i < m; i++) {
    for (int j = 0; j < n; j++) {
        arr[i][j] = i + j * m;
    }
}

for (int[] row : arr) {
    System.out.println(Arrays.toString(row));
}
//[0, 7]
//[1, 8]
//[2, 9]
//[3, 10]
//[4, 11]
//[5, 12]
//[6, 13]

---

^{另见：Printing a snake pattern using an array}