JavaOOP/lab_2/main.java

package lab_2;

import org.jetbrains.annotations.Contract;
import org.jetbrains.annotations.NotNull;

import java.util.Scanner;

public class main {

    public static short protectedInput(String inputPrompt, String errorMessage, Scanner input) {
        short read_variable;

        do {
            try {
                System.out.println();
                System.out.print(inputPrompt);

                read_variable = input.nextShort();
                break;
            } catch (Exception e) {
                System.out.println(errorMessage);
                input.nextLine();
            }
        } while (true);

        return read_variable;
    }

    @NotNull
    public static String format(int number) {
        int width = String.valueOf(number).length() + 1;

        return "|%" + width + "d ";
    }

    @Contract(pure = true)
    public static double average(@NotNull short[] row) {
        short sum = 0;

        for (short element : row) {
            sum += element;
        }

        return (double) sum / row.length;
    }

    public static void main(String[] args) {
        short rows, columns;

        Scanner input = new Scanner(System.in);

        final short a = protectedInput("Input a constant to multiply a matrix by: ",
                "A constant must be a short-data type integer, try again.", input);

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

        do {
            rows = protectedInput("Rows: ",
                    "A number of rows must be a short-data type integer, try again.", input);
        } while (rows <= 0);

        do {
            columns = protectedInput("Columns: ",
                    "A number of columns must be a short-data type integer, try again.", input);
        } while (columns <= 0);

        input.close();

        short[][] matrix_B = new short[rows][columns];

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

        String format = format(rows * columns);

        for (short i = 0; i < rows; i++) {
            for (short j = 0; j < columns; j++) {
                matrix_B[i][j] = (short) ((i + 1) * (j + 1));

                System.out.printf(format, matrix_B[i][j]);
            }

            System.out.println("|");
        }

        System.out.println();
        System.out.println("Matrix a×B:");

        format = format(rows * columns * a);

        for (short i = 0; i < matrix_B.length; i++) {
            for (short j = 0; j < matrix_B[i].length; j++) {
                matrix_B[i][j] *= (a);

                System.out.printf(format, matrix_B[i][j]);
            }

            System.out.println("|");
        }

        System.out.println();
        System.out.println("Averages of each row:");

        for (short[] row : matrix_B) {
            System.out.println(average(row));
        }
    }
}