IB Computer Science D.1 Objects as a Programming Concept Questionbank

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')
}

public int compareWith(String flightID)
{ if (myFlight.getId().equals(flightID)) { return 0; }
else { return 1; }
}

public int compareWith(Arrival anotherArrival)
{ // missing code
}

// ... plus accessor and mutator methods
}

The code below outlines part of the FlightManagement class used in this program.

For the purposes of this exam only arriving flights are being considered.

public class FlightManagement
{
private Arrival$$ inbound; // array of inbound airplanes
private int last = -1; // index of last used entry
public FlightManagement()
{ inbound = new Arrival$200$;
}
public void add(Arrival newArrival)
{ // missing code that adds the newArrival to the array inbound
// sorted by ETA, and updates last
}

private int search (String flightID)
{ // missing code that searches the array inbound and
// returns the index of the Arrival object with flightID
}

public Arrival remove(String flightID)
{ Arrival result;
int index = search(flightID);
result = inbound$index$;
while (index < last)
{ inbound$index$ = inbound$index + 1$;
index++;
}
last--;
return result;
}

// ... many more methods
}

The method search in the FlightManagement class searches the array inbound and returns the index of the Arrival object with the given flightID.

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;
    }
}

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.

A fitness tracking application records various physical activities. Each activity is stored as a Workout object within a TrainingLog.

To improve the user experience, the application provides a feature to organize the workout history. Users can extract specific workouts into a separate 'Focus List' based on their intensity or performance metrics.

For this system, the focus list is generated by identifying all workouts that exceed a user-defined distance threshold. When a workout is moved to the Focus List, it is removed from the main training log to prevent duplication in the primary view.

A software development company is designing a system to manage tasks and projects. The system uses objects to represent tasks and projects. Each task has attributes such as title, description, and status, while each project has a name, deadline, and a collection of tasks.