Modify the application so it will only accept customer type codes r and c. It should also discard any extra entries on the customer type line. If the user enters an invalid code, the application should display an error message and ask the user to enter a valid code. This should be done first before the user enters a subtotal:

import java.text.NumberFormat;
import java.util.Scanner;

public class InvoiceApp
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
String choice = "y";

while (!choice.equalsIgnoreCase("n"))
{
// get the input from the user
System.out.print("Enter customer type (r/c): ");
String customerType = sc.next();
System.out.print("Enter subtotal: ");
double subtotal = sc.nextDouble();

// get the discount percent
double discountPercent = 0;
if (customerType.equalsIgnoreCase("R"))
{
if (subtotal < 100)
discountPercent = 0;
else if (subtotal >= 100 && subtotal < 250)
discountPercent = .1;
else if (subtotal >= 250)
discountPercent = .2;
}
else if (customerType.equalsIgnoreCase("C"))
{
if (subtotal < 250)
discountPercent = .2;
else
discountPercent = .3;
}
else
{
discountPercent = .1;
}


// calculate the discount amount and total
double discountAmount = subtotal * discountPercent;
double total = subtotal - discountAmount;

// format and display the results
NumberFormat currency = NumberFormat.getCurrencyInstance();
NumberFormat percent = NumberFormat.getPercentInstance();
System.out.println(
"Discount percent: " + percent.format(discountPercent) + "\n" +
"Discount amount: " + currency.format(discountAmount) + "\n" +
"Total: " + currency.format(total) + "\n");

// see if the user wants to continue
System.out.print("Continue? (y/n): ");
choice = sc.next();
System.out.println();
}
}
}