I need an explanation to the code below line by line and thank you.

import java.math.BigDecimal;

import java.util.Scanner;

public class Calculator {

public static void main(String[] args) {

char choice = 'y';

while (choice == 'y' || choice == 'Y') {

BigDecimal num1, num2;

Scanner input = new Scanner(System.in);

System.out.print("Enter first number: ");

num1 = input.nextBigDecimal();

System.out.print("Enter second number: ");

num2 = input.nextBigDecimal();

System.out.print("Enter the operator (+,-,*): ");

char op = input.next().charAt(0);

BigDecimal result;

switch (op) {

case '+':

result = num1.add(num2);

break;

case '-':

result = num1.subtract(num2);

break;

case '*':

result = num1.multiply(num2);

break;

default:

System.out.println("You entered an invalid operator");

result = BigDecimal.ZERO;

break;

}

System.out.println("result= " + result);

System.out.print("Do you wish to continue (Y/N)? ");

choice = input.next().charAt(0);

}

}

}