Introduction Course Information Object Oriented Concepts Operators & Control Statements Assignment 3. CS Java. Introduction to Java

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1 CS Java Introduction to Java Andy Mroczkowski uamroczk@cs.drexel.edu Department of Computer Science Drexel University January 28, 2008 / Lecture 2

2 Introduction Course Information Basic Course Information Schedule Outline Object Oriented Concepts Key Concepts An Example Objects in Java Inheritance & Polymorphism Operators & Control Statements Operators Conditional Statements Loops Assignment 3

3 Welcome! Course materials adapted from Nadya Belov

4 Welcome! Course materials adapted from Nadya Belov

5 Course Information Instructor Andy Mroczkowski Office Location: TBD Office Hours: TBD Course CS Java Web: uamroczk/cs190 Book: Thinking in Java, 4th Edition Previous edition available for free at wwww.mindview.net/books/tij/

6 Attendance & Lectures Attendance is required Lectures posted online prior to class Tests & Quizzes Midterm 2/18 Final 3/ Quizzes or in-class assignments Assignments 4-5 Assignments Must be turned in on-time Subject to change

7 Attendance & Lectures Attendance is required Lectures posted online prior to class Tests & Quizzes Midterm 2/18 Final 3/ Quizzes or in-class assignments Assignments 4-5 Assignments Must be turned in on-time Subject to change

8 Schedule 1 Jan 7 Jan 14 Jan 21 Jan 28 Feb 4 Feb 11 Feb 18 Mar 3 Feb 25 Mar 10 Mar 17 Course Overview, Introduction to Java No Class (tentative) No Class (University Holiday) Object Oriented Concepts, Control Statements Inheritance, Reuse, Abstraction, Classes, Interfaces Scope, Public/Protected/Private, Java Exception Handling Midterm, File I/O Threading Graphical User Interfaces (AWT, Swing) Networking, Special Topics (Encryption, Reflection) Final 1 Also subject to change

9 Key Concepts Information Hiding Encapsulation Re-use and Extensibility

10 Key Concepts Information Hiding Encapsulation Re-use and Extensibility

11 Key Concepts Information Hiding Encapsulation Re-use and Extensibility

12 Key Concepts Information Hiding Encapsulation Re-use and Extensibility

13 Information Hiding Coined by L. Parnas, On the Criteria to Be Used in Decomposing System into Modules, 1977

14 Encapsulation Related to, but not synonymous with Information Hiding

15 Re-use and Extensibility

16 So what is an Object? A definition An object has a state, a set of behaviors and an identity. Grady Booch

17 An Example

18 An Example Identity (Type)? State (Properties)? Behaviors (Methods)?

19 An Example Identity (Type)? State (Properties)? Behaviors (Methods)?

20 An Example Identity (Type)? State (Properties)? Behaviors (Methods)?

21 An Example Identity (Type)? State (Properties)? Behaviors (Methods)?

22 An Example Identity (Type) Bicycle State (Properties) Color Size Number of gears Current gear Behaviors (Methods) Pedal Change gears Brake

23 An Example Identity (Type) Bicycle State (Properties) Color Size Number of gears Current gear Behaviors (Methods) Pedal Change gears Brake

24 An Example - Formalized Bicycle color size numberofgears pedal() changegear() brake()

25 An Example - More Formalized Bicycle String color float size int numberofgears void pedal() boolean changegear(int newgear) boolean brake()

26 An Example - in Java class B i c y c l e { p u b l i c S t r i n g c o l o r ; p u b l i c f l o a t s ize ; p u b l i c i n t numberofgears ; p u b l i c void pedal ( ) { } p u b l i c boolean changegear ( i n t newgear ) { r e t u r n f a l s e ; } } p u b l i c boolean brake ( ) { r e t u r n f a l s e ; }

27 Objects in Java Everything is an object. Almost.

28 Objects in Java Everything is an object. Almost.

29 Primitive Types byte short int long float double boolean char void

30 Objects in Java Everything else is an object.

31 Creating an Object B i c y c l e mybike = new B i c y c l e ( ) ;

32 Accessing Properies System. out. p r i n t l n ( mybike. c o l o r ) ; mybike. size = ;

33 Calling Methods mybike. pedal ( ) ; mybike. changegear ( 5 ) ; mybike. brake ( ) ;

34 Inheritance & Polymorphism

35 Inheritance

36 Inheritance - Formalized Bicycle String color float size int numberofgears void pedal() boolean changegear(int newgear) boolean brake() MountainBicycle boolean hasfrontsuspension boolean hasrearsuspension

37 Inheritance - in Java class MountainBicycle extends B i c y c l e { boolean hasfrontsuspension ; boolean hasrearsuspension ; }

38 Multiple Inheritance

39 Polymorphism

40 Operators & Control Statements

41 Operator Soup * / % + - [] (). new expr++ expr-- ++expr --expr +expr -expr ~! ==!= & ^ && << >> >>> < > <= >= instanceof = += -= *= /= %= &= ^= = <<= >>= >>>=? :

42 Types of Operators Mathematical, Relational, Logical, Bitwise, Assignment,... Unary, Binary, Ternary

43 Types of Operators Mathematical, Relational, Logical, Bitwise, Assignment,... Unary, Binary, Ternary

44 Types of Operators Mathematical, Relational, Logical, Bitwise, Assignment,... Unary, Binary, Ternary

45 Mathematical * / % + i

46 Mathematical Shorthand expr++ expr- ++expr -expr

47 Relational < > <= >= instanceof ==!=

48 Logical &&!

49 Bitwise ~ & ^ << >> >>>

50 Assignment Operator: = Meaning: Take the value on the right hand side and assign it to the variable on the left hand side rvalue: on the right hand side lvalue : the left hand side must be a distinct, named variable

51 Assignment Shorthand Mathematical = += -= *= /= %= Bitwise &= ^= = <<= >>= >>>=

52 Unary, Binary, Ternary Unary:! - Binary: + - && == = Not to be confused with Bitwise Ternary:? : Boolean-expression? true-statement : false-statement

53 Precedence Example a = x + y - 2/2 + z; vs. a = x + (y - 2)/(2 + z);

54 Special String Operators + += Example S t r i n g s1 = " Peanut B u t t e r " ; S t r i n g s2 = " J e l l y Time " ; S t r i n g s3 = s1 + " " + s2 ; Also know as concatentaion.

55 Conditional Statements

56 if - else Statements Form 1 i f ( Boolean expression ) statement Form 2 i f ( Boolean expression ) statement else statement

57 if - else Statements (cont.) Example i f ( a < b ) p r i n t ( " a i s smaller " ) ; else i f ( a > b ) p r i n t ( " b i s smaller " ) ; else p r i n t ( " a and b are equal " ) ;

58 switch Statements Form switch ( i n t e g r a l s e l e c t o r ) { case i n t e g r a l value1 : statement ; break ; case i n t e g r a l value2 : statement ; break ; / /.. d e f a u l t : statement ; }

59 Example switch Statements (cont.) switch ( c ) { case a : case e : case i : case o : case u : p r i n t ( " vowel " ) ; break ; case y : p r i n t ( " sometimes a vowel " ) ; break ; d e f a u l t : p r i n t ( " consonant " ) ; }

60 Loops

61 for Loops Form f o r ( i n i t i a l i z a t i o n ; Boolean expression ; step ) statement Example f o r ( char c = 0; c < 128; c ++) System. out. p r i n t l n ( " value : " + ( i n t ) c + " character : " + c ) ;

62 while Loops Form while ( Boolean expression ) statement Example long now = new Date ( ). gettime ( ) ; long l a t e r = new Date ( ). gettime ( ) ; while ( now < l a t e r ) { now = new Date ( ). gettime ( ) ; }

63 Assignment 3

Course Status Polymorphism Containers Exceptions Midterm Review. CS Java. Introduction to Java. Andy Mroczkowski

Course Status Polymorphism Containers Exceptions Midterm Review. CS Java. Introduction to Java. Andy Mroczkowski CS 190 - Java Introduction to Java Andy Mroczkowski uamroczk@cs.drexel.edu Department of Computer Science Drexel University February 11, 2008 / Lecture 4 Outline Course Status Course Information & Schedule