Folien

Transcription

Folien

Fallstudie: Videothek-Verwaltung
Aufgabenstellung
• Abrechnung einer Videothek:
– 3 Arten von Videos
• Normalpreis
• Neuerscheinung
• Kindervideos
€ 2 + € 1,50 pro Tag ab dem 3. Tag
€ 3 pro Tag
€ 1,50 plus € 1,50 pro Tag ab dem 4. Tag
– Bonuspunkte pro Ausleihung
• Normalpreis
• Neuerscheinung
• Kindervideo
• Gewünschte Ausgabe:
1 Punkt
1 Punkt + 1 Zusatzpunkt, ab 2 Tage
1 Punkt
Kunde: Max Glotzmann
Star Trek
Terminator VII
König der Löwen
Gesamtpreis
Bonuspunkte
UE zu SW 2
Fallstudie OO-Entwurf: Videothek-Verwaltung
3,50
6,00
3,00
12,50
4
A.1
Klasse Movie (Filme)
reine Datenklasse
Movie
class Movie {
public static final int regular = 0,
newRelease = 1,
children = 2;
private String title;
private int kind;
- title
- kind
getTitle()
setKind(n)
getKind()
public Movie (Sting s, int n) { title = s; kind = n; }
public String getTitle () { return title; }
public void setKind (int n) { kind = n; }
public int getKind () { return kind; }
}
get- und set-Methoden
• machen es leichter, private Daten später zu ändern.
• erlauben es, read-only-Attribute zu modellieren (z.B. title).
• kosten allerdings Effizienz und machen Programm größer.
UE zu SW 2
A.2
Klasse Rental (Ausleihung)
Ausleihvorgang eines Films durch einen Kunden.
Ebenfalls reine Datenklasse
Rental
- movie
- days
class Rental {
private Movie movie;
private int days;
getMovie()
getDays()
public Rental (Movie m, int d) { movie = m; days = d; }
public Movie getMovie () { return movie; }
public int getDays () { return days; }
}
UE zu SW 2
A.3
Klasse Customer (Kunde)
Pro Kunde werden sein Name und
die von ihm ausgeliehenen Filme gespeichert.
class Customer {
private String name;
private List rentals = new LinkedList();
Customer
- name
- rentals
getName()
addRental(r)
makeInvoice()
public Customer (String name) { this.name = name; }
public String getName () { return name; }
public void addRental (Rental r) { rentals.add(r); }
public String makeInvoice () {
// liefert einen Rechnungstext über alle ausgeliehenen Filme
// hier steckt die gesamte Steuerlogik!
}
}
UE zu SW 2
A.4
Customer: makeInvoice()
int price = 0, total = 0, bonus = 0; // Preise in Euro-Cent
Iterator films = rental.iterator();
StringBuffer sb = new StringBuffer("Kunde: " + name + "\n");
while (films.hasNext()) {
Rental r = (Rental) films.next();
int kind = r.getMovie().getKind(), days = r.getDays();
switch (kind) {
case Movie.regular:
price = 200;
if (days > 2)
price += (days - 2) * 150; break;
case Movie.newRelease: price = days * 300; break;
case Movie.children:
price = 150;
if (days > 3)
}
bonus++; if (kind==Movie.newRelease && days>1) bonus++;
sb.append("\t" + r.getMovie().getTitle() + "\t");
sb.append(price/100 + "," + price %100 + "\n");
total += price;
}
sb.append("\nGesamtbetrag:\t"+ total/100 + "," + total%100);
sb.append("\nBonuspunkte:\t" + bonus);
return
sb.toString();
UE zu
SW 2
A.5
}
Customer: makeInvoice() zerlegen
int price = 0, total = 0, bonus = 0;
StringBuffer sb = new StringBuffer("Kunde: " + name);
int kind = r.getMovie().getKind(), days = r.getDays();
switch (kind) {
computeChargeFor(Rental
r)
case Movie.regular:
price = 200;
if (days > 2)
case Movie.newRelease: price = days * 300; break;
price = 150;
if (days > 3)
}
computeBonusFor (Rental r)
bonus++; if (kind==Movie.newRelease && days>1) bonus++;
total += price;
}
UE zu
SW 2
A.6
return
sb.toString();
}
Customer: compute Charge/Bonus For (r)
public int computeChargeFor (Rental r) {
int price = 0;
int kind = r.getMovie().getKind(), days
switch (kind) {
case Movie.regular:
price = 200;
if (days > 2)
price += (days
case Movie.newRelease: price = days *
price = 150;
if (days > 3)
price += (days
}
return price;
}
= r.getDays();
- 2) * 150; break;
300; break;
- 3) * 150; break;
public int computeBonusFor (Rental r) {
return (r.getMovie().getKind() == Movie.newRelease &&
r.getDays() > 1) ? 2 : 1;
}
UE zu SW 2
A.7
Customer: makeInvoice() NEU
int price = 0, total = 0, bonus = 0; // Preise in Euro-Cent
StringBuffer sb = new StringBuffer("Kunde: " + name);
price = computeChargeFor(r);
bonus += computeBonusFor(r);
total += price;
}
return sb.toString();
}
computeCharge/BonusFor beziehen sich auf Rental nicht auf Customer
==> Methoden in die Klasse Rental verschieben
UE zu SW 2
A.8
Rental: getCharge / getBonus ()
public int getCharge () {
int price = 0;
int kind = movie.getKind();
switch (kind) {
case Movie.regular:
price = 200;
if (days > 2)
price += (days - 2)
case Movie.newRelease: price = days * 300;
price = 150;
if (days > 3)
price += (days - 3)
}
return price;
}
public int getBonus () {
return (movie.getKind()==Movie.newRelease &&
}
Customer:
...
price = r.getCharge();
bonus += r.getBonus();
...
}
UE zu SW 2
* 150; break;
break;
* 150; break;
days>1) ? 2 : 1;
A.9
Movie: getCharge / getBonus (days)
public int getCharge
int price = 0;
switch (kind) {
case regular:
if (days > 2)
case newRelease:
case children:
if (days > 3)
}
return price;
}
(int days) {
price
price
price
price
price
= 200;
+= (days - 2) * 150; break;
= days * 300; break;
= 150;
+= (days - 3) * 150; break;
public int getBonus (int days) {
return (kind == newRelease && days > 1) ? 2 : 1;
}
Rental:
public int getCharge() { return movie.getCharge(days); }
public int getBonus () { return movie.getBonus(days); }
UE zu SW 2
A.10
Price - Klassen
abstract class Price {
public abstract int getCharge (int days);
public int getBonus (int days) { return 1; }
}
class RegularPrice extends Price {
public int getCharge (int days) {
if (days > 2) return 200 + (days-2)*150; else return 200;
}
}
class NewPrice extends Price {
public int getCharge (int days) { return days * 300; }
public int getBonus (int days) {
if (days > 1) return 2; else return 1;
}
}
class ChildPrice extends Price {
public int getCharge (int days) {
if (days > 3) return 150 + (days-3)*150; else return 150;
}
}
UE zu SW 2
A.11
Implementierung von Movie
class Movie {
private String title;
private Price price;
public Movie (String title, Price price) {
this.title = title; this.price = price;
}
public
public
public
public
public
String getTitle () { return title; }
void setPrice (Price p) { price = p; }
Price getPrice () { return price; }
int getCharge (int days) { return price.getCharge(days); }
int getBonus (int days) { return price.getBonus(days); }
}
UE zu SW 2
A.12
Implementierung von Rental
class Rental {
private Movie movie;
private int days;
public Rental (Movie movie, int days) {
this.movie = movie; this.days = days;
}
public
public
public
public
Movie getMovie () { return movie; }
int getDays () { return days; }
int getCharge () { return movie.getCharge(days); }
int getBonus () { return movie.getBonus(days); }
}
UE zu SW 2
A.13
Implementierung von Customer
class Customer {
private String name;
private List rentals = new LinkedList();
public Customer (String name) { this.name = name; }
public void addRental (Rental r) { rentals.add(r); }
int price = 0, total = 0, bonus = 0;
Iterator films = rentals.iterator();
StringBuffer sb = new StringBuffer("Kunde: " + name + "\n");
price = r.getCharge();
bonus += r.getBonus();
total += price;
}
return sb.toString();
}
UE zu SW 2
A.14
}
Videothek-Applikation (1)
class VideoApp {
public static final Price regular = new RegularPrice();
public static final Price newRelease = new NewPrice();
public static final Price children = new ChildPrice();
private Map customers = new HashMap();
private Map movies = new HashMap();
void addMovie (Movie movie) {
movies.put(movie.getName(), movie);
}
void addCustomer (Customer customer) {
customers.put(customer.getName(), customer);
}
...
UE zu SW 2
A.15
Videothek-Applikation (2)
...
public static void main (String[] args) {
VideoApp bb = new VideoApp();
// bb … Blockbuster
Customer mg = new Customer("Max Glotzmann");
bb.addCustomer(mg);
Movie m1 = new Movie("Star Trek", regular),
m2 = new Movie("Terminator VII", newRelease);
m3 = new Movie("König der Löwen", children);
bb.addMovie(m1); bb.addMovie(m2); bb.addMovie(m3);
mg.addRental(new Rental(m1, 3));
System.out.println(mg.makeInvoice());
}
}
UE zu SW 2
A.16

Folien

Transcription

Similar documents

RFID bei Bibliomedia

Geschäftsbriefe