Doubling a Matrix

Question

I\'ve created a two dimensional matrix and populated it with random numbers. I\'ve then printed it out. I need help creating a second matrix that is twice the size of the first,

Answer 1

import java.util.Scanner;
import java.util.Random;


public class MatrixDoubler {
    public static void main(String[] arg) {
        Scanner keyboard = new Scanner(System.in);
        Random rand = new Random();

        System.out.println("Enter the size of the matrix");

        int size = keyboard.nextInt();
        int A[][] = new int[size][size];

        for (int row = 0; row < size; ++row) {
            for (int col = 0; col < size; ++col) {
                A[row][col] = rand.nextInt(10);
            }
        }

        System.out.println("Matrix A:");
        printMatrix(A);

        int[][] B = doubleMatrix(A);

        System.out.println("Matrix B:");
        printMatrix(B);
    }

    private static int[][] doubleMatrix(int[][] A) {
        int rows = A.length;
        assert(rows > 0);
        int cols = A[0].length;
        assert(cols > 0);

        int B[][] = new int[rows * 2][cols * 2];

        for (int row = 0; row < rows * 2; ++row) {
            for (int col = 0; col < cols * 2; ++col) {
                B[row][col] = A[row / 2][col / 2];
            }
        }

        return B;
    }

    private static void printMatrix(int[][] M) {
        for(int i = 0; i < M.length; i++) {
            for(int j = 0; j < M.length; j++) {
                System.out.print(M[i][j] + " ");
            }

            System.out.println();   
        }
    }
}