试图在 Java 中使用数组，但不知道我做错了什么

Question

I am trying to achieve the following structure,

100    200    300    400    500    600    700    800
200    400    600    800  1,000  1,200  1,400  1,600

I tried with the following code but I can't make it work.

public class Main {

    public static void main(String[] args) {
        int cols = 5;
        int rows = 4;
        int number = 100;
        int [][] doublearr = new int [rows][cols];


        for (int i = 0; i < doublearr.length ;i ++){
            for(int j=0; j < doublearr[i].length; j++){
                    doublearr[0][0] = number;
                    doublearr[i][j] = doublearr[0][0] *( j+1);
                    System.out.print("\t" + doublearr[i][j]);
            }
            System.out.println();
        }
    }
    }

This is the output i am getting for this.

100 200 300 400 500
100 200 300 400 500
100 200 300 400 500
100 200 300 400 500

I really appreciate if any one can point me in the right direction. thanks in advance.

Answer 1

You want to change your column into 8 and row into 2 because your output value is 8 * 2 = 16 . Your equation is doublearr[0][0] * (j + 1)

If your equation is doublearr[0][0] * (j + 1) :

1. 100 * (0 + 1) = 100

2. 100 * (1 + 1) = 200

3. 100 * (2 + 1) = 300

4. 100 * (3 + 1) = 400

5. 100 * (4 + 1) = 500

6. 100 * (5 + 1) = 600

7. 100 * (6 + 1) = 700

8. 100 * (7 + 1) = 800

9. 100 * (0 + 1) = 100

10. 100 * (1 + 1) = 200

11. 100 * (2 + 1) = 300

12. 100 * (3 + 1) = 400

13. 100 * (4 + 1) = 500

14. 100 * (5 + 1) = 600

15. 100 * (6 + 1) = 700

16. 100 * (7 + 1) = 800

If equation change to doublearr[0][0] * (j + 1) * (i + 1) :

1. 100 * (0 + 1) * (0 + 1)= 100

2. 100 * (1 + 1) * (0 + 1)= 200

3. 100 * (2 + 1) * (0 + 1)= 300

4. 100 * (3 + 1) * (0 + 1)= 400

5. 100 * (4 + 1) * (0 + 1)= 500

6. 100 * (5 + 1) * (0 + 1)= 600

7. 100 * (6 + 1) * (0 + 1)= 700

8. 100 * (7 + 1) * (0 + 1)= 800

9. 100 * (0 + 1) * (1 + 1)= 200

10. 100 * (1 + 1) * (1 + 1)= 400

11. 100 * (2 + 1) * (1 + 1)= 600

12. 100 * (3 + 1) * (1 + 1)= 800

13. 100 * (4 + 1) * (1 + 1)= 1000

14. 100 * (5 + 1) * (1 + 1)= 1200

15. 100 * (6 + 1) * (1 + 1)= 1400

16. 100 * (7 + 1) * (1 + 1)= 1600

Here down is my code:

public class MyClass {
    public static void main(String[] args) {
    int cols = 8;
    int rows = 2;
    int number = 100;
    int [][] doublearr = new int [rows][cols];


    for (int i = 0; i < doublearr.length ;i ++){
        for(int j=0; j < doublearr[i].length; j++){
                doublearr[0][0] = number;
                doublearr[i][j] = doublearr[0][0] * (j + 1) * (i + 1);
                System.out.print(" " + doublearr[i][j]);
        }
        System.out.println();
    }
}
}

Answer 2

If you want to print double of the above column then you will need to do a small change:

for (int i = 0; i < doublearr.length ;i ++){
    for(int j=0; j < doublearr[i].length; j++){
            doublearr[0][0] = number;
            doublearr[i][j] = doublearr[0][0] *( j+1);
            System.out.print("\t" + doublearr[i][j]);
    }
  number*=2;  // add this line
    System.out.println();
}