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...