The document describes modifications to a Java program that calculates mobile phone package costs. The program is updated to calculate and display potential savings for customers of Package A if they switched to Package B or C, and for Package B customers if they switched to Package C. It compares the calculated costs under each package and displays any savings or a message if there are no savings.

1. JAVA
Modify the program you wrote for Programming Challenge 13 so it also calculates and
displays the amount of money Package A customers would save if they purchased Package
B or C, and the amount of money Package B customers would save if they purchased
Package C. If there would be no savings, no message should be printed.
My Code:
import java.util.Scanner;
public class MobilePackage {
final static double COSTPACKA = 39.99;
final static double COSTPACKB = 59.99;
final static double COSTPACKC = 69.99;
final static double ADDITIONALCOSTA = 0.45;
final static double ADDITIONALCOSTB = 0.40;
final static double MINUTESPACKA = 450;
final static double MINUTESPACKB = 900;
public static void main(String[] args) {
double minused = 0, billA, billB;
String choice;
Scanner sc = new Scanner(System.in);
do {
System.out.println("Select a subscription package: ");
System.out.println("A: Package A");
System.out.println("B: Package B");
System.out.println("C: Package C");
System.out.println("Q: Quit");

2. System.out.print("Enter package: ");
choice = sc.next();
switch (choice) {
case "A":
System.out.print("How many minutes were used during the month: ");
minused = sc.nextDouble();
if (minused <= MINUTESPACKA) {
System.out.println("Total cost is: " + COSTPACKA);
// saving with package B
System.out.println("No savings with package B");
// saving with package C
System.out.println("No savings with package C");
} else {
billA = ((minused - MINUTESPACKA) * ADDITIONALCOSTA) + COSTPACKA;
billB = (minused - MINUTESPACKB) * ADDITIONALCOSTB + COSTPACKB;
System.out.println("Total cost is: " + billA + "$");
// saving with package B
if (minused <= MINUTESPACKB && billA > COSTPACKB) {
System.out.println("Savings with package B: " + (billA - COSTPACKB) + "$");
} else if (minused > MINUTESPACKB && billA > billB) {
System.out.println("Savings with package B: " + (billA - billB) + "$");
} else {
System.out.println("No savings with package B");

3. }
// saving with package C
if (billA > COSTPACKC) {
System.out.println("Savings with package C: " + (billA - COSTPACKC) + "$");
} else {
System.out.println("No savings with package C");
}
}
System.out.println();
break;
case "B":
System.out.print("How many minutes were used during the month: ");
minused = sc.nextDouble();
if (minused <= MINUTESPACKB) {
billA = ((minused - MINUTESPACKA) * ADDITIONALCOSTA) + COSTPACKA;
System.out.println("Total cost is:" + COSTPACKB);
// saving with package A
if (minused <= MINUTESPACKA) {
System.out.println("Savings with package A: " + (COSTPACKB - COSTPACKA) + "$");
} else if (minused > MINUTESPACKA && billA < COSTPACKB) {
System.out.println("Savings with package A: " + (COSTPACKB - billA) + "$");
} else {
System.out.println("No savings with package A");

4. }
// saving with package C
System.out.println("No savings with package C");
} else {
billB = (minused - MINUTESPACKB) * ADDITIONALCOSTB + COSTPACKB;
System.out.println("Total cost is: " + billB + "$");
// saving with package A
System.out.println("No savings with package A");
// saving with package C
if (billB > COSTPACKC) {
System.out.println("Savings with package C: " + (billB - COSTPACKC) + "$");
} else {
System.out.println("No savings with package C");
}
}
System.out.println();
break;
case "C":
System.out.print("How many minutes were used during the month: ");
minused = sc.nextDouble();
if (minused <= MINUTESPACKB) {
billA = ((minused - MINUTESPACKA) * ADDITIONALCOSTA) + COSTPACKA;
billB = (minused - MINUTESPACKB) * ADDITIONALCOSTB + COSTPACKB;

5. System.out.println("Total cost is:" + COSTPACKC);
// saving with package A
if (minused <= MINUTESPACKA) {
System.out.println("Savings with package A: " + (COSTPACKC - COSTPACKA) + "$");
} else if (minused > MINUTESPACKA && billA < COSTPACKC) {
System.out.println("Savings with package A: " + (COSTPACKC - billA) + "$");
} else {
System.out.println("No savings with package A");
}
// saving with package C
if (minused <= MINUTESPACKB) {
System.out.println("Savings with package C: " + (COSTPACKC - COSTPACKB) + "$");
} else if (minused > MINUTESPACKB && billB < COSTPACKC) {
System.out.println("Savings with package C: " + (COSTPACKC - billB) + "$");
} else {
System.out.println("No savings with package C");
}
} else {
System.out.println("Total cost is: " + COSTPACKC + "$");
// saving with package A
System.out.println("No savings with package A");
// saving with package B
System.out.println("No savings with package B");

6. }
System.out.println();
break;
case "Q":
System.out.print("Thank you!");
break;
default:
System.out.println("Invalid Choice");
System.out.println();
}
} while (!choice.equals("Q"));
sc.close();
}
}