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1 !" # %"# #&#'(##) %#*+, +-,.-% /00&&& 00

2 Software Development Today & 0 ()## +

3 Course Concept 3 3 3!" '&/? #A4 # 3 / = >4() (#)9 (<) 9 3 (4 #:4;) 2 ( 2 ) & 4( ) 4 () (6& 7) & & 0 ()## 1

4 Course Outline, Timetable +B ' 1- ''. = -B = '4& +-= & +G = ( 4<) F ''4 -+ ' E! D35 -C! +1! 6#7 1,! C 9 #&4# 0 ()## B

5 Exercises and Lab Classes! &4B 9>1-+,,F /%#+,4+-B //00&&& 00 > 3/? H 0 ()## F

6 Exam ' > '& ()## C

7 ' '

8 What is an Object? ' () () () () & /Light lt = new Light(); /lt.on(); 0 ()## G

9 Alan Kay s 5 Rules @ & 0 ()## E

10 Classes ( ) 5 '& / B 0 ()## -,

11 Class Instance Object "/ Light lt = new Light(); Light lt I '3 0 ()## --

12 Example of a Simple Class class Rectangle { int x; int y; int width; int height; void draw() { //... } void erase() { //... } } >/ >J-,,KJ+,,K &J-,K J+,K 0 ()## -+

13 Objects Hide Complexity ' 0 ()## -1

14 Example of Hidden Complexity 3 5& > class Person { double height ; double weight ; double calculatebmi () { return weight/(height*height); } } < Person p = new Person(); p.height = 1.80 ; p.weight = 75 ; p.calculatebmi () ; 0 ()## -B

15 3

16 The Object-oriented Approach 6> & (4 4 4 ) "L - 3% && + ' % & 1 ' %& & (6'%(7) M 43 /N 0 ()## -C

17 1. Relationship between SWM and PM & () & (#") ( ) () () () () (/# M= N) 0 ()## -.

18 2. Resilience of SWM A 45 O4 &&P ( ) () () () () 0 ()## -G

19 3. Reusability of SWMs P > 4 4 P ( ) 6 # 3 #A 0 ()## -E

20 Concept: Inheritance I '; ; ; & > ; ( 34 4 #) 3 &() () #A &() () # &() () &() () () 0 ()## +,

21 Inheritance II '&/ (draw()) & (length()) & 0 ()## +-

22 Concept: Overriding I #& 0 ()## ++

23 Deduce Meaning from Context I/ " " " I Q/ " " " 0 ()## +1

24 Concept: Method Overloading >/ class SuperWasher { void wash (Shirt s) {... } void wash (Car c) {...} void wash (Dog d) {...} } R =4 & 0 ()## +B

25 Goal: Safe and Flexible Substitutability ()&5 / ' &s 34#A Shape s ; //... s.draw () ; s.erase () ; # 3 #A 0 ()## +F

26 Means: Polymorphism Shape draw() 3# Ellipse draw() erase() Circle draw() erase() M) / > () N 0 ()## +C

27 Means: Dynamic Binding " ( 4& ) draw() draw() draw() draw() Circle.draw() Square.draw() Rectangle.draw() > 0 ()## +.

28 Example: Writing General Code void dostuff (Shape s) { s.erase () ; //... s.draw () ; } //... Circle c = new Circle () ; Triangle t = new Triangle () ; Line l = new Line () ; dostuff (c) ; dostuff (t) ; dostuff (l) # # &4 & # # 0 ()## +G

29 Variability and Polymorphism (1) #A ()/ Circle createshape () Shape createshape () </ Shape s=createshape();//expects "Shape" 0 ()## +E

30 Variability and Polymorphism (2) ()/ rotate(shape s) rotate(circle c) </ rotate (new Circle ()) ()/ class Shape { public Color color ; } color / new Shape ().color = Color.black ; color / Color defaultcolor = new Shape ().color ; 0 ()## 1,

31 Reuse " 4/ -? (>) + " (>) 1 >& B >& 0 ()## 1-

32 Reuse by Composition 5& > 36%7 67 '> 34& O & () "MBN M+N 0 ()## 1+

33 Reuse by Inheritance 5& > > '6'7 I && &() () &() () &() () &() () 0 ()## 11

34 Inheritance vs. Composition? 4 L 3 L "MBN " &MCN 3 "MBN " &MCN M+N "R '4 A 0 ()## 1B

35 "5&

36 Object-Oriented Programs > ()## 1C

37 References %&4 0 0 () = R a 0 ()## 1.

38 Reference Type Variables & "a:=b4 ' a4 br a b a b &545&& 5R 0 ()## 1G

39 Comparison 3() a==b c!=a 3 a.equals(c) a.equals(b) c a b '&4 A( ) 0 ()## 1E

40 Methods 3 (4 4) <returntype> <methodname>(<argument-list>) { <method-body> }} () 0 ()## B,

41 Message Sending ( 4 ) / 67 ; - D(-,,)K ; () 0 ()## B-

42 Constructor > P!5 () P R 0 ()## B+

43 Constructor Example! 3 class Person { Object() String name; Person(String paramname) { name = paramname; } } class Student extends Person { int studentid; Student(String paramname, int paramstudentid) { super(paramname); studentid = paramstudentid; } } super(paramname) Person(String) P name 0 ()## B1

44 References to Current Object / %&& & L #/? (67 )&!this #self ' this4&!super 0 ()## BB

45 References to current object this super this super 67 5 S 5 S =/super.superr class Square extends Shape { dostuff () { } } super.draw () ; this.draw () ; # &() () #A &() () 0 ()## BF

46 Visibility * & ()## BC

47 Casting <& > '& > & </ & () () " () () () () &() &/ 4 5 &> Shape s = new Circle(); Circle c = (Circle) s; // ok: s happens to be a Circle Rectangle r = (Rectangle) s; // runtime error 0 ()## B.

48 Runtime Type Identification 65&7 4 / if (s instanceof Rectangle) { Rectangle r = (Rectangle)s ; } else // what to do??? throw new RuntimeException ( unexcpected type + r.getclass ().getname ()) ; <D 0 ()## BG

49 0 ()## BE

50 3

51 Classes Revisited & / () ( ) () & ( 67)4 & ( ) & Shape Ellipse Circle c = new Circle() 0 ()## F-

52 Abstract Classes & 0 ()## F+

53 Interfaces 3 3 A 67 5 interface List { public void add(object o); public Object get(int index); } class ArrayList implements List { private Object[] data ; public void add (Object o) { /* Implementation */ } public Object get (int index) { /* Implementation */ } } 0 ()## F1

54 Multiple Inheritance 3 " 9 FemaleDoctor & Doctor Woman ( ) 3& = =!44 43TT 0 ()## FB

55 Forms of Typing # 5 5 > 0 ()## FF

56 Garbage ' 5&& & & & 0 ()## FC

57 Metaclass S U 67 5&& I (4 444 ) 44 43TT S S S ( #5) 0 ()## F.

58 Metaclass Example 9!4java.lang.Class #()V 33 J 3 ()K # (W3/WT3 = ())K MN J3 ()K (J,KX KTT) # (W /WT MN= ())K Y (=/I 4 ) 0 ()## FG

59 Java s Metaclass Replacements!567 ' / static / abstract class WebPage { static private int numberofaccesses; static public getnumberofaccesses(){ return numberofaccesses ; } }// class WebPage abstract interface 0 ()## FE

60 Levels of Object-Orientation /4 67 ( ) %/ ( 3TT) &/4 (!) ('/444 4#5) 0 ()## C,

61 Generics P & & 5(5& &/ () ( >) ) &/ P/ () ( >) A/ ( ) ( >) 0 ()## C-

62 Generics in Java class List<E> { void add(e data); E get(int index); /*... */ }; "/ List doglist = new ArrayList(); doglist.add(new Dog()); doglist.add(new Cat()); 00 "/ List<Dog> doglist = new ArrayList<Dog>(); doglist.add(new Dog()); doglist.add(new Cat()); 00 =&!F!F/ #? ' 0 ()## C+

63 Generics in C++? =& 3& template<class T> class List { public: void add (T data) ; T get (int index) ; List () { /*... */ } private: //... the data... }; 0 ()## C1

64 Generics with Wildcards?& 5&(& ) List<?> list = new ArrayList<String> () ; list.add (new Object ()) ; // does this work? Object o = list.get (0) ; // what about this? 3 " ( ) 6 #7 void draw (List<? extends Shape> shapes) { for (Shape s : shapes) s.draw(); } /? super Shape %5&shapes 4 shapes Shape ( Shape) 0 ()## CB

65 Generics Catches O& void addcircle (List<? extends Shape> shapes) { shapes.add (new Circle ()); //Why does this not work? } shapes List<Rectangle> ' 4/ void addcircle (List<Shape> shapes) { shapes.add (new Circle ()) ; //now this works } shapes List<Shape>. # Circle Shape4&5 0 ()## CF

66 Covariance List<Shape> List<Circle>L =RR O! String[] Object[] 0 ()## CC

67 On OO: Links and References ( 9: /00&&& 0Z500A0 S(!) /00&&& #U!F / F,0 )* 43 / # 3# 8() 0 ()## C.