D.2 Features of OOP Questionbank

A smartphone app is being developed to manage tasks and reminders. The app uses classes such as Task, Reminder, and Event, which inherit from a base class ScheduleItem.

A generic Event class is defined as follows:

class Event
{
private String eventID;
private int numberOfRaces;
private Race$$ races;
private Race finals;
public Event(String ID, int numberOfRaces)
{
eventID = ID;
races = new Race$numberOfRaces$;
for(int i = 0; i < numberOfRaces; i++)
{
races$i$ = new Race();
}
finals = new Race();
}
public void addSwimmers()
{
// fills the qualifying heats with swimmers
}
public void fillFinals()
{
// fills the finals race with the best 8 from the qualifying heats
}
// more methods()
}

The Event class above assumes that the event has more than 8 swimmers and requires qualifying heats. However, an event with less than 9 swimmers has no qualifying heats, so the original Event class was inherited by a new class FinalsOnlyEvent.

An airline company is updating its reservation system, which includes classes like Seat, EconomySeat, and BusinessSeat. EconomySeat and BusinessSeat inherit from Seat.

A hotel chain has a loyalty scheme in which customers are awarded 1000 points for each day they stay in one of their hotels. With these points, customers can achieve one of three status levels: Gold, Silver or Bronze. The level will determine the extra services to which they are entitled.

The total number of points collected during the current year will determine which of the three status levels they are assigned for the following year: For example only the points collected in 2018 will determine the status level for 2019.

Occasionally, new customers receive additional bonus points as part of a promotion.

The Pointsclass keeps details of the points and status levels of each customer.

public class Points
{
private String memberId; // id of the hotel customer
private int totalPoints; // this year's points
private int bonusPoints; // any bonus points given to this year's new member
private String statusNow; // current(this year's)status
private String statusNextYear; // following year's status
private Visits$$ allVisits = new Visits$366$;//details of each visit
// during this year
int y; // number of visits this year
public Points(String id) // constructor for new member
{
memberId = id;
bonusPoints = 0;
y = 0;
statusNow = 'Bronze';
}

//constructor for new member given bonus points (valid for current year only)
public Points(String id, int bp)
{
memberId = id;
bonusPoints = bp; // multiples of 1000 - maximum number is 5000
y = 0;
statusNow = 'Bronze';
}

// all the accessor and mutator methods are present but not shown
public Visits getAllVisits(int v)
{
return allVisits$v$;
}
public void addVisit(Visits v) // adds a new Visit object to the array
{
allVisits$y$ = v;
y = y + 1;
}

isGold() {code missing}
calculateTotalPoints(){code missing}
daysMissing(){code missing}
}

The instance variables in the Pointsclass are preceded by the modifier private. The choice of modifier affects the way in which these variables are accessed or used.

The customers will be assigned one of three levels for the following year (Gold, Silver or Bronze) depending upon the current year’s total points as follows.

• Bronze = less than 10 000 points
• Silver = 10 000 or more but less than 50 000
• Gold = 50 000 or more.

In 2018, Tim became a member for the first time and was awarded a bonus of 1000 points. So far, in 2018, Tim has stayed three times at one of these hotels. The first visit lasted 2 days, the second visit lasted 1 day and the third visit lasted 6 days.

The different Pointsobjects are stored in an array which is declared globally in the main (driver) class as follows:Points[] allPoints = new Points[10000];

A company is developing an AI chatbot system with classes such as Chatbot, CustomerServiceBot, and SalesBot. Both CustomerServiceBot and SalesBot inherit from Chatbot.

A company is developing a suite of financial software tools, utilizing programming teams in different countries.

A multimedia software company is creating a graphics editor with classes such as Shape, Circle, and Rectangle. Both Circle and Rectangle inherit from Shape.