IB Computer Science D.3 Program Development Questionbank

The management of the company will launch a new scheme to give every 50th car driver and every 60th motorcyclist a free coffee voucher. The code for printing this voucher has already been created and is activated by calling the static method Vouchers.printCoffeeVoucher().

A getKind() method has already been added to the Vehicle class, which returns a char value indicating whether it is a car (c) or a motorbike (m).

One test performed on the finished code was defined as follows:

An airport uses an object-oriented program to keep track of arrivals and departures of planes. There are many objects in this system and some are listed below.

The code below outlines the Arrival class used in this program.

public class Flight
{ private String id;
public String getId() {return this.id;}
// ... more variables, accessor and mutator methods
}
**
public class** Arrival
{ private Flight myFlight;
private String sta; // Scheduled Time of Arrival ('hh:mm')
private int runway;
private String gate;
private int delay;
private boolean landed;

public Arrival(Flight myFlight, String sta)
{ **this.**myFlight = myFlight;
**this.**sta = sta;
**this.**runway = 0;
**this.**gate = null;
**this.**delay = 0;
**this.**landed = false;
}

public void addDelay(int newDelay)
{ **this.**delay = newDelay;
}

public String getETA()
{ // calculates the Estimated Time of Arrival (ETA) of the flight
// by adding the delay to the sta and returning the result as a // String ('hh:mm') }

A municipal library system manages a large collection of physical resources across several branches. To streamline operations, a digital cataloging system is being developed to track individual books and their availability.

Each book in the system has a title and a recorded page count. The system must also track whether the book is currently checked out to a member or available on the shelf. The books are managed within specific branches, each represented by a collection with a defined maximum capacity.

A developer has drafted the following Book and Library classes as part of the initial model:

public class Book {
    private String title;
    private int pages;
    private boolean borrowed;

    public Book(String t, int p) {
        title = t;
        pages = p;
        borrowed = false;
    }

    public void setBorrowed(boolean status) {
        borrowed = status;
    }

    public String getTitle() {
        return title;
    }

    public int getPages() {
        return pages;
    }
}

public class Library {
    private Book[] collection;
    private String branchName;

    public Library(String bName, int max) {
        branchName = bName;
        collection = new Book[max];
    }

    public void addBook(Book b, int index) {
        if (index >= 0 && index < collection.length) {
            collection[index] = b;
        }
    }

    public String getBranchName() {
        return branchName;
    }
}

The array inbound in the FlightManagement class is sorted by Estimated Time of Arrival (ETA).

Assume the following classes/fields/methods are available:

• Class FlightManagement

  • Arrival[] inbound (sorted by Arrival's ETA in increasing order)
  • int last (index of the last occupied element in inbound, so valid entries are 0 to last)
  • Arrival remove(String flightID) (removes and returns the Arrival whose flight has ID flightID)
  • void add(Arrival newArrival) (inserts newArrival into inbound so that it remains sorted by ETA)

• Class Arrival

  • String getETA() (returns ETA as a String in the format "HH:MM" so lexicographic order matches time order)
  • boolean getLanded() (returns true if the flight has landed)
  • Flight getMyFlight() (returns the associated Flight)
  • int compareWith(Arrival other) (returns a negative value if this arrival's ETA is before other's ETA, 0 if equal, positive if after)
  • void addDelay(int minutes) (updates this arrival's ETA by adding minutes)

To improve customer satisfaction, a supermarket chain wants to create an object-oriented program (OOP) to simulate the lines of customers at the check-outs in their point of sale (POS) system.

This point of sale (POS) system consists of several check-out counters. After filling their shopping carts with items, customers line up at one of the check-out counters. In most cases, they wait in line until it is their turn to pay.

Three real-world objects are implemented using the following classes:

The UML diagram for the class POSline is provided below.