Myltiplayer

import java.util.Scanner;

// Create a class named MultiplyBigNumber
public class MultiplyBigNumber {
    // Create a main method
    public static void main(String[] args) {
        // Create a Scanner object named scanner
        Scanner scanner = new Scanner(System.in);

        // Read a String named number1 from the scanner
        String number1 = scanner.nextLine();
        // Read a String named number2 from the scanner
        String number2 = scanner.nextLine();

        // Close the scanner
        scanner.close();

        // If one of the numbers is negative and the other is not, print "-" sign
        if ((number1.charAt(0) == '-' || number2.charAt(0) == '-') && (number1.charAt(0) != '-' || number2.charAt(0) != '-')) {
            System.out.print("-");
        }

        // If both numbers are negative, remove the "-" sign from both of them
        if (number1.charAt(0) == '-' && number2.charAt(0) == '-') {
            number1 = number1.substring(1);
            number2 = number2.substring(1);
        }

        // Call the multiply method with number1 and number2 and print the result
        System.out.println(multiply(number1, number2));
    }

    // Create a static method named multiply that takes two Strings as parameters and returns a String
    static String multiply(String num1, String num2) {
        // Get the lengths of the numbers and store them in int variables named len1 and len2
        int len1 = num1.length();
        int len2 = num2.length();

        // If either length is 0, return "0"
        if (len1 == 0 || len2 == 0)
            return "0";

        // Create an int array named result with size len1 + len2 and fill it with zeros
        int[] result = new int[len1 + len2];

        // Create two int variables named i_n1 and i_n2 and assign them to 0
        int i_n1 = 0;
        int i_n2 = 0;

        // Loop from the last index of num1 to the first index
        for (int i = len1 - 1; i >= 0; i--) {
            // Create an int variable named carry and assign it to 0
            int carry = 0;
            // Convert the char at the current index of num1 to an int and store it in an int variable named n1
            int n1 = num1.charAt(i) - '0';

            // Set i_n2 to 0
            i_n2 = 0;

            // Loop from the last index of num2 to the first index
            for (int j = len2 - 1; j >= 0; j--) {
                // Convert the char at the current index of num2 to an int and store it in an int variable named n2
                int n2 = num2.charAt(j) - '0';

                // Multiply n1 and n2 and add carry and the value at result[i_n1 + i_n2], store the result in an int variable named sum
                int sum = n1 * n2 + carry + result[i_n1 + i_n2];

                // Set carry to sum / 10
                carry = sum / 10;

                // Set result[i_n1 + i_n2] to sum % 10
                result[i_n1 + i_n2] = sum % 10;

                // Increment i_n2 by 1
                i_n2++;
            }

            // If carry is not 0, add it to result[i_n1 + i_n2]
            if (carry > 0)
                result[i_n1 + i_n2] += carry;

            // Increment i_n1 by 1
            i_n1++;
        }

        // Create an int variable named i and assign it to result.length - 1
        int i = result.length - 1;

        // While i is greater than or equal to 0 and result[i] is equal to 0, decrement i by 1
        while (i >= 0 && result[i] == 0)
            i--;

        // If i is equal to -1, return "0"
        if (i == -1)
            return "0";

        // Create a StringBuilder object named sB
        StringBuilder sB = new StringBuilder();

        // While i is greater than or equal to 0, append result[i] to sB and decrement i by 1
        while (i >= 0)
            sB.append(result[i--]);

        // Return sB as a String
        return sB.toString();
    }
}