Chapter 5, Problem 8PP

a.

Method heading for each method:

• The method heading is “public void sellTickets(int number)” that takes a parameter “number” of integer type and update the number of tickets sold and total sales.
• The method heading is “public void phoneSalesOver()” that takes no parameters and sales can be made at the venue only...

b.

Preconditions and postconditions of each method:

• Precondition and postcondition of “public void sellTickets(int number)” method.
  • Precondition: checks whether the input is positive and less than or equal to number of unsold tickets.
  • Postcondition: update the number of tickets sold and total sales.
• Precondition and postcondition of “public void phoneSalesOver()” method.
  • Precondition: None.
  • Postcondition: This method is used to sell the tickets only at the venue.
• Precondition and postcondition of “public int getTicketsSold()” method...

c.

Test class for some Java statement:

//Create an object for ConcertPromoter

ConcertPromoter con = new ConcertPromoter();

//Call initialize () method

con.initialize("The Ducks", 100, 10.00, 12.00);

//Display the header message

System.out.println("Concert Promoter Sales Program started");

//Create an object for Scanner class

Scanner reader = new Scanner(System.in);

//Declare and initialize the flag variable

boolean done = false;

//Loop executes until the true

while (!done)

{

/*Call phoneSalesOnly() method to check whether sales through phone. */

    if (con.phoneSalesOnly())

        //Display the Sales details

System.out.println("Sell tickets (S), Change to venue sales (V), Finish selling (F)");

  /*Otherwise, display the modified sales details. */

    else

System.out.println("Sell tickets (S), Finish selling (F)");

    //Read the input from user

    String response = reader.next();

    //Check whether the input is equal to "F"

    if (response...

d.

Implementation of class:

ConcertPromoter.java:

//Import the java package

import java.util.Scanner;

//Define the class

public class ConcertPromoter

{

    //Declare the required variables

    private String bandName;

    private int capacity;

    private int ticketsSold;

    private double costPhone;

    private double costVenue;

    private double totalSales;

    private boolean salesAreByPhone;

    //Define the sellTickets() method

    public void sellTickets(int number)

    {

/*Check whether the number is inbetween "0" and ticket left. */

        if (number > 0 && number <= getTicketsLeft())

        {

            //Add the ticket sold number

            ticketsSold += number;

/*Call getSaleCost() method to calculate the total sales...

e.

List of extra methods and attributes needed for this implementation:

There is no extra attributes are needed for this implementation.

The extra methods that were used apart from the mentioned methods are,

• public void initialize() method:
  • This method is used to initialize the declared variables.
• public boolean phoneSalesOnly() method:
  • This method is used to return the true when user making sales through the phone. Otherwise, return false.
• public String getSalesReport() method:
  • This method is used to return the sales report of sold tickets count and their amount...

f.

Implementation of class:

ConcertPromoter.java:

//Import the java package

import java.util.Scanner;

//Define the class

public class ConcertPromoter

{

    //Declare the required variables

    private String bandName;

    private int capacity;

    private int ticketsSold;

    private double costPhone;

    private double costVenue;

    private double totalSales;

    private boolean salesAreByPhone;

    //Define the initialize() method

public void initialize(String band, int max, double costOverPhone, double costAtVenue)

    {

        //Initialize the declared variables

        bandName = band;

        capacity = max;

        ticketsSold = 0;

        costPhone = costOverPhone;

        costVenue = costAtVenue;

        totalSales = 0.0;

        salesAreByPhone = true;

    }

    //Define the doTicketSale() method

    public void doTicketSale()

    {

        //Read the maximum ticket to sell from user

System.out.println("How many tickets to sell? (Maximum " + getTicketsLeft() + ")");

        Scanner reader = new Scanner(System.in);

        int toSell = reader.nextInt();

        //Call sellTickets() method to initialize the flag

        boolean saleCompleted = sellTickets(toSell);

        //Check whether the flag is "true"

        if (saleCompleted)

/*Call getSaleCost() method to calculate the ticket cost and then display it. */

System.out.println("The cost of the tickets is " + getSaleCost(toSell));

        //Otherwise, display the error message

        else

System.out.println("Sorry, unable to complete that sale");

    }

    //Define the sellTickets() method

    public boolean sellTickets(int number)

    {

/*Check whether the number is in between "0" and ticket left. */

        if (number > 0 && number <= getTicketsLeft())

        {

            //Add the ticket sold count

            ticketsSold += number;

/*Call getSaleCost() method to calculate the total sales. */

            totalSales += getSaleCost(number);

            //Return the true

            return true;

        }

        //Otherwise, return the false

        else

            return false;

    }

    //Define the getSaleCost() method

    public double getSaleCost(int number)

    {

        //Declare the variable

        double saleCost = number;

        //Check whether sales by phone is "true"

        if (salesAreByPhone)

            //Calculate the sale cost with cost phone

            saleCost *= costPhone;

/*Otherwise, calculate the sale cost with cost venue. */

        else

            saleCost *= costVenue;

        //Return the sale cost

        return saleCost;

    }

    //Define the phoneSalesOver() method

    public void phoneSalesOver()

    {

        //Set the flag as "false"

        salesAreByPhone = false;

    }

    //Define the getTicketsSold() method

    public int getTicketsSold()

    {

        //Return the ticket sold

        return ticketsSold;

    }

    //Define the getTicketsLeft() method

    public int getTicketsLeft()

    {

        //Return the remaining ticket

        return capacity - ticketsSold;

    }

    //Define the getTotalSales() method

    public double getTotalSales()

    {

        //Return the total sales

        return totalSales;

    }

    //Define the phoneSalesOnly() method

    public boolean phoneSalesOnly()

    {

        //Return the phone sales

        return salesAreByPhone;

    }

    //Define the getSalesReport() method

    public String getSalesReport()

    {

        //Return the sales report

return "Sales for " + bandName + ":  Tickets sold: " + ticketsSold + " for " + totalSales;

    }

    //Define the main() method

    public static void main(String[] args)

    {

        //Create an object for ConcertPromoter

        ConcertPromoter con = new ConcertPromoter();

        //Call initialize () method

con...