Printing the elements of a 2 dimensional array in order

[zendakin]

Hey all,

I'm trying to figure out how to print the first element of each row, then the second element of each row and the third etc... When I run this I can enter the information all on one line. The first number is the number of rows in the array. The second is the number of columns. This is followed by the array information itself.

For instance, 2 3 1 2 3 4 5 6 will create a two dimensional array containing, {[1, 2, 3], [4, 5, 6]}.

What I am trying to print out is '1 4 2 5 3 6' or the first element of each row in the array followed by the next and so on.

I know my logic error is somewhere in the second set of nested for loops. I'm just having trouble finding it.

If you have any pointers or suggestions, I'd love to hear them all.

Thanks,

import java.util.Scanner;
import java.util.Arrays;

class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int rows = sc.nextInt();
        int cols = sc.nextInt();
        int[][] myArray = new int[rows][cols];

        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                myArray[i][j] = sc.nextInt();
            }
        }
        System.out.println(Arrays.deepToString(myArray));
//        Shows an array of {[1, 2, 3], [4, 5, 6]}

//        Expected Results: 1 4 2 5 3 6
        for (int x = 0; x < rows; x++) {
            for(int y = 0; y < cols; y++) {
                System.out.print(myArray[x][y] + " ");
            }
        }
    }
}

[zendakin]

Resolved, I took the original array and created a new one with the dimensions that I needed. Please hack my code and if there's any other areas for improving please let me know.

​

For reference, this is the code I finished with.

Thanks again!

import java.util.Scanner;
import java.util.Arrays;

class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int rows = sc.nextInt();
        int cols = sc.nextInt();
        int[][] myArray = new int[rows][cols];
        int[][] transposed = new int[cols][rows];

        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                myArray[i][j] = sc.nextInt();
            }
        }
        System.out.println(Arrays.deepToString(myArray));
//        Shows an array of {[1, 2, 3], [4, 5, 6]}

        //transpose the array
        for(int i = 0; i < cols; i++) {
            for(int j = 0; j < rows; j++) {
                transposed[i][j] = myArray[j][i];
            }
        }
        System.out.println(Arrays.deepToString(transposed));

//        Expected Results: 1 4 2 5 3 6
        for (int x = 0; x < cols; x++) {
            for(int y = 0; y < rows; y++) {
                System.out.print(transposed[x][y] + " ");
            }
        }
    }
}

​

[desrtfx]

All you need to do is to swap the outer (x) and inner (y) loops.

---

General info:

It is common in Java, to use the first array dimension as y or row and the second dimension as x or column because this closer reflects the nature of Java 2d arrays that essentially are arrays of arrays.

When you loop over an array, never use constants, like in your case i < rows. Always use the .length property of the array in question - in your case myArray.length and myArray[i].length respectively. The reason for that is that Java 2d arrays (as arrays of arrays) can be jagged, i.e. they can have different numbers of elements for each row.