but first. Project 1: Movie Theatre Simulation Inheritance and - PDF document

but first…. • Project 1: Movie Theatre Simulation Inheritance and Polymorphism – Handouts / Description now on Web site – Due Dates: The Payroll App • Minimum Effort Due: April 7, 2002 • Full Project Due: April 14, 2002 Movie Theatre Simulation Movie Theatre Simulation • You are to program a simulation of the workings • You will be programming a simulation of a multiplex theatre complex. – There will be a global “clock” indicating the • Rules: current time of day of the simulation – A Theatre Complex has a number of individual theatres – You will be updating the current time as the – Each theatre shows an individual movie a number of simulation progresses through “the day” times based on a given schedule – The state of the objects of the system will – A movie may be shown in more than one theatre change as the current time changes. – Customers can buy tickets in advance for $7 ($4 if ticket is purchased before 4pm) Movie Theatre Simulation Movie Theatre Simulation • Major objects • You will need to implement the following classes: – TheatreSim – main object that drives the simulation – TheatreComplex – represents a multiplex containing a – Movie multitude theatres – Schedule – Theatre – an individual theatre – Theatre – Movie – a movie – TheatreComplex – Schedule – The schedule that a movie will follow at a given individual theatre. Will also maintain the “state” • Specs for these classes are given via of a movie playing at a given theatre. Javadocs and UML diagrams. – Clock – Master clock for the simulation – Time – representing time of day 1

Movie Theatre Simulation Movie Theatre Simulation • A simulation will be defined by two input files (to • Minimum Effort Requirement TheatreSim) – At the very least, you will need to implement – Complex Definition File – the Movie class. • Contains what theatres are playing what movies and when. – Simulation Control file – Submission of this is due April 7 th • List of “events” that happen during the day – Must submit minimum effort requirement to – “buy” – customer buys ticket pass the course. – “advance” – advance the global clock – “status” – Print status report (what’s going on “now” at each theatre) – “summary” – Print summary (how many tickets sold and $$ collected for each theatre) – “schedule” – Print s schedule Movie Theatre Simulation Movie Theatre Simulation • Grading • Submission – First criteria: Program must run correctly! – All submissions (minimum effort + final code) – Deductions for are done using try • Unclear or bad implementation (35%) – Minimum effort due: April 7 th • Bad programming style (including non-use of RCS) (30%) – Weighting – Complete project due: April 14 th • Movie 15% • Schedule 25% • Theatre 25% – No late submissions! • TheatreComplex 25% • All classes together 10% Movie Theatre Simulation Interface data • Questions? • All data associated with an interface, regardless of how they are declared are: – Read-only – Public – Final – Static 2

Interface data A bit more on interfaces public interface Foo { • The Observable/Observer design pattern – Use this pattern when you have one class that public int a = 30; must react to the changes in another class. public static int b = 40; public static final int c = 50; – The second class(Observer) is said to observe the first class (Observable). private int d = 34; // not allowed – In the project, the Clock will be observed by the protected int e = 444; // not allowed Theatre objects. } Observer/Observable ( java.util ) Observer/Observable ( java.util ) • The Observable public void update (Observable o, Object arg) – Observable is defined as a class. – The Observable maintains a set of Observers who are interested when the Observable o – the observable object changes arg – an argument with optional details about • Observer the change. – Observer is defined as an interface – Classes that implement Observer must define an update method Observer/Observable ( java.util ) Observer/Observable ( java.util ) • When an update is made to an Observable, • In our simulation an update message is sent to all Observers – All Theatre objects are registered with the currently in the Observable’s set. global Clock as observers. – When the current time of the Clock changes (via the simulation), the Clock will • Observable.notifyObservers(Ob notifyObservers() ject arg) is used for this purpose • I.e. the update method for all Theatres will be called. 3

Back to our Payroll app Observer/Observable • Questions? • Class hierarchy for theatre app Performer isA isA Actor Musician Guitarist Pianist Drummer Back to our Payroll app Changes to the Payroll class • Instrument hierarchy public class Payroll { private Performer performer[]; private int nPerf; Instrument public void addPerformer (Performer P) { if (nPerf == MAXPERF) { System.err.println ("Payroll is full!"); Guitar Piano Drums } else { performer[nPerf] = P; nPerf++; } } calculateTotalPay A look at Instruments public abstract class Instrument { public double calculateTotalPay() private double rentalCost; { double sum = 0.0; protected Instrument (double cost) for (int i=0; i < nPerf; i++) { sum += performer[i].calculatePay(); rentalCost = cost; } return sum; } public double getWeeklyRental () { return rentalCost; } } 4

A look at instruments A look at Performer public class Guitar extends Instrument { public abstract class Performer implements Comparable { private String myName; public Guitar () private double payPerPerf; { private int nPerformances; super (200.0); } protected Performer (String name, double rate) { protected Guitar (double rate) myName = name; { payPerPerf = rate; super (rate); nPerformances = 0; } } } } A look at Performer Now Actor public abstract double calculatePay(); public class Actor extends Performer { private static final double PAYRATE = 200.0; protected double getBasePay() { public Actor (String name) return nPerformances * payPerPerf; { super (name, PAYRATE); } } public void perform (int n) public double calculatePay () { { nPerformances = n; return getBasePay(); } } } And Musician Finally Musician subclasses public class Drummer extends Musician { public class Musician extends Performer { public Drummer (String name) private Instrument myInstrument; private static final double PAYRATE = 100.0; { super (name, new Drums()); public Musician(String name, Instrument I) } { super(name, PAYRATE); } myInstrument = I; } public double calculatePay() { return getBasePay() + myInstrument.getWeeklyRental(); } 5

• Any questions? • Tomorrow – Exceptions 6