Open the project named ch02_ex3_Invoice that’s in the ex_starts directory.
Then, open the file named InvoiceApp.java
Modify the code so the application ends only when the user enters “n” or ‘N”.
As it is now, the application ends when the user enters anything other than “y”
or “Y”. To do this, you need to use a not operator (!) with the equalsIgnoreCase method.
This is illustrated by the third example in figure 2-14. Then, compile this class and test this change by entering 0 at the Continue prompt.
Modify the code so it provides a discount of 25 percent when the subtotal is greater than or equal to 500. Then, test this change.
Modify the code so it displays the number of invoices, the average invoice amount, and the average discount amount when the user ends the program. Then, test this change.
public class InvoiceApp
public static void main(String args)
// welcome the user to the program
System.out.println(“Welcome to the Invoice Total Calculator”);
System.out.println(); // print a blank line
// create a Scanner object named sc
Scanner sc = new Scanner(System.in);
// perform invoice calculations until choice isn’t equal to “y” or “Y”
String choice = “y”;
// get the invoice subtotal from the user
System.out.print(“Enter subtotal: “);
double subtotal = sc.nextDouble();
// calculate the discount amount and total
double discountPercent= 0.0;
if (subtotal >= 200)
discountPercent = .2;
else if (subtotal >= 100)
discountPercent = .1;
discountPercent = 0.0;
double discountAmount = subtotal * discountPercent;
double total = subtotal – discountAmount;
// display the discount amount and total
String message = “Discount percent: ” + discountPercent + “n”
+ “Discount amount: ” + discountAmount + “n”
+ “Invoice total: ” + total + “n”;
// see if the user wants to continue
System.out.print(“Continue? (y/n): “);
choice = sc.next();