01.TheMatrix

public class Validation {
    public static int isPositiveNum(Scanner scanner) {
        int firstNum;
        do {
            System.out.println("Must be positive number between 1 and 10!");
            while (!scanner.hasNextInt()) {
                System.out.println("Must be positive number between 1 and 10!");
                scanner.next(); //This is important!
            }
            firstNum = scanner.nextInt();
        } while (firstNum <= 0 || firstNum > 10);
        System.out.println("Thank you! Got it!" );
        return firstNum;
    }
    public static int isNum(Scanner scanner){
        int num;
        while (!scanner.hasNextInt()){
            System.out.println("Please enter number!");
            scanner.next();
        }
        num = scanner.nextInt();
        return num;
    }

}
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("Please enter size of matrix!");
        //Validate and get size of matrix.
        int size = Validation.isPositiveNum(scanner);
        int[][] firstMatrix = new int[size][size];
        //Fill first matrix with user input.
        for (int i = 0; i < size; i++) {
            for (int j = 0; j < size; j++) {
                System.out.printf("Please, for first matrix, enter number, for position %d-%d : ", i, j);
                int num = Validation.isNum(scanner);
                firstMatrix[i][j] = num;
            }
        }
        System.out.println("Thank you! Let`s now fill the second matrix!");
        //Fill second matrix with user info.
        int[][] secondMatrix = new int[size][size];
        for (int i = 0; i < size; i++) {
            for (int j = 0; j < size; j++) {
                System.out.printf("Please, for second matrix, enter number, for position %d-%d : ", i, j);
                int num = Validation.isNum(scanner);
                secondMatrix[i][j] = num;
            }
        }
        int doubleSize = size * 2;
        //Create new matrix to add first and second.
        int[][] firstAndSecondMatrix = new int[size][doubleSize];
        for (int i = 0; i < size; i++) {
            for (int j = 0; j < doubleSize; j++) {
                if (j < size) {
                    firstAndSecondMatrix[i][j] = firstMatrix[i][j];
                } else {
                    firstAndSecondMatrix[i][j] = secondMatrix[i][j - size];
                }
            }
        }
        //Create new matrix for collection the sum of first and second!
        int[][] sumMatrix = new int[size][size];
        for (int i = 0; i < size; i++) {
            for (int j = 0; j < size; j++) {
                sumMatrix[i][j] = firstMatrix[i][j] + secondMatrix[i][j];
            }
        }
        //Create a new matrix for direct sum.
        int[][] directMatrix = new int[doubleSize][doubleSize];
        for (int i = 0; i < doubleSize; i++) {
            for (int j = 0; j < doubleSize; j++) {
                if (i < size && j < size) {
                    directMatrix[i][j] = firstMatrix[i][j];
                } else if (i >= size && j >= size) {
                    directMatrix[i][j] = secondMatrix[i - size][j - size];

                }
                //Initialization of empty slots.
                //else {
                //directMatrix[i][j] = 0;
                //}
            }
        }
        //Print results.
        System.out.println("First and second matrix : ");
        for (int i = 0; i < size; i++) {
            for (int j = 0; j < doubleSize; j++) {
                System.out.printf("%d ", firstAndSecondMatrix[i][j]);
                if (j == size-1)
                {
                    System.out.printf(" | ");
                }
            }
            System.out.println();
        }

        System.out.println("Matrix of sum of first and second matrix : ");
        for (int[] row :
                sumMatrix) {
            for (int num :
                    row) {
                System.out.printf("%d ", num
                );
            }
            System.out.println();
        }
        System.out.println("Direct matrix :");
        for (int[] row :
                directMatrix) {
            for (int num :
                    row) {
                System.out.printf("%d ", num);
            }
            System.out.println();
        }
    }
}


import java.util.Scanner;