【解決方法】行数が列数と異なる場合にスパイラル行列を生成する方法は?

Proceed to Spiral class and implement its static method:

int[][] spiral(int rows, int columns)
Return a two-dimensional array coming in the form of a table and containing numbers from 1 up to rows * columns. The size of the table will be specified by the given parameters.
Numbers fill the "table" clockwise from the top-level corner in a spiral manner.
For example, for parameter values (3, 4), the output array should be:
1  2  3  4
10 11 12  5
9  8  7  6

For example, for parameter values (5, 5), the output array should be:
1    2   3   4   5
16  17  18  19   6
15  24  25  20   7
14  23  22  21   8
13  12  11  10   9


This is my code:

<pre>
class Spiral {
    static int[][] spiral(int rows, int columns) {
        int[][] matrix = new int[rows][columns];
        int col_start = 0, col_end = rows - 1;
        int row_start = 0, row_end = columns - 1;
        int element = 1;
 
        while(col_start <= col_end && row_start <= row_end) {
            //top
            for(int j = col_start; j <= col_end; j++) {
                matrix[row_start][j] = element++;
            }
 
            // right side
            for(int i = row_start + 1; i <= row_end; i++) {
                matrix[i][col_end] = element++;
            }
 
            //bottom side
            for (int j = col_end - 1; j >= col_start; --j) {
                matrix[row_end][j] = element++;
            }
 
 
            //left side
            for (int i = row_end - 1; i > row_start; --i) {
                matrix[i][col_start] = element++;
 
            }
            col_start++;
            col_end--;
            row_start++;
            row_end--;
        }
 
        return matrix;
    }
    public static void main(String[] args) {
        {
            int[][] spiral = Spiral.spiral(4, 5);
 
            for (int i = 0; i < spiral.length; i++) {
                for (int j = 0; j < spiral[i].length; j++) {
                    System.out.print(String.format("%4s", spiral[i][j]));
                }
                System.out.println();
            }
        }
    }
}

私が試したこと：

Basically I know how to generate the matrix in spiral form. When the number of rows is equal with the number of columns the result is correct.
But when the number of rows is different than the the number of columns I have a wrong result.

Do you know what should I do to find the correct result?