[NHN NEXT] Java 강의 - Week2

PL�� in�� Java�� Week02��

Object & Class

조영호�� [email protected]��

G o a l ��

O O 패러다임 �� 이해 ��

설 명 만 �� 많 고 �� 코 드 는 �� 별 로 �� 없 어 요 ��

Conceptual Perspective��

Implementation Perspective��

객체지향�� Object-Orientation��

개념�� 관점��

구현�� 관점��

Conceptual Perspective��

Implementation Perspective��

객체지향�� Object-Orientation��

개념�� 관점��

구현�� 관점��

Object & Collaboration��

Object-Oriented Programming

Language��

To p i c s ��

Conceptual Perspective

Implementation Perspective

Object & Class

OO == 실세계의�� 모방?��

실무�� 관점에서는�� 부적절하지만��

개념을�� 이해하는�� 데는�� 유용함��

Object-Orientation��

http://www.slideshare.net/baejjae93/roles-responsibilities-collaborations

Object

Object Object

협력��

message

Object Object

Object Object

협력에�� 참여하는�� 객체��

message

Object

메시지를�� 처리하기�� 위한�� 행동��

Behavior

Object

Object Object

message

Object

behavior

행동에�� 필요한�� 상태��

State

Object

Object Object

OO Design��

message? message

State�� Behavior��

state?

State?��

plusOne ?

State?��

plusOne

plusOne

minusOne

setZero

plusOne

setZero

2

State?��

plusOne 1

State?��

2

plusOne 1

2

5

plusOne

plusOne

Dynamic��

plusOne

plusOne

plusOne

Dynamic��

2

3

6

plusOne

plusOne

plusOne

Dynamic��

2

3

6

Complex!��

Static��

2 3

6

1 2

5

Number

Static(Behavior)��

2 3

6

1 2

5

Number

plusOne behavior��

Static(Behavior + State)��

2 3

6

1 2

5

Number

value

plusOne

state��

behavior��


2 3

6

1 2

5

Number

value

plusOne value = value + 1

state��

behavior��


Number

Simple!��

value


state��

behavior��


Number

Type�� value


state��

behavior��


2 3

6

1 2

5

Number

value


Object�� Type�� instance of��

To p i c s ��



Object & Class

in Class-Based OOPL��

Type��

Number

value


Number

value


member variable��

method��

Class��

state��

behavior��

Implemented By


2 3

6

1 2

5

Object�� Class�� instance of�� Number

value



method��

in Java OOPL��

Class��

Number

value


public class Number { int number; void plusOne() { number = number + 1; } }

syntax


method��

Object

Class

To p i c s ��



Object & Class

Elevator Object��

Behavior��

moveUp(floor)��

Behavior��

moveDown(floor)��

Class와�� Method를�� 작성해�� 보세요��

public class Elevator { void moveUp(int floor) { } void moveDown(int floor) { } }

State��

moveUp(floor)��

moveDown(floor)��

State를�� 표현하기�� 위해�� Member Variable을�� 추가해�� 보세요��

public class Elevator { int floor; void moveUp(int floor) { } void moveDown(int floor) { } }

this��

this��

this��

public class Elevator { int floor; void moveUp(int floor) { this.floor = floor; } void moveDown(int floor) { this.floor = floor; } }

Constraint��

1층��

10층��

this�� public class Elevator { int floor; void moveUp(int floor) { if (floor > 10 || this.floor >= floor) { return; } this.floor = floor; } void moveDown(int floor) { if (floor <1 || this.floor <= floor) { return; } this.floor = floor; } }

diff C C#/Java��

Value Type(Primitive Type)��

Reference Type��

boolean, char, byte, short , int , long, float , double

String, Object, Array …

Pointer Type ?��

Stack Heap

Value Type�� ReferenceType��

Stack & Heap��

boolean, char, byte, short , int , long,

float , double String, Object, Array

diff C C#/Java��

new��

Heap

Object Instantiation��

Elevator elevator = new Elevator();

Class = Type��

ClassName()��

Memory Allocation��

Variable��

Stack Heap

Stack & Heap��

floor = 1 elevator address

Elevator Object

public class Elevator { ... public static void main(String[] args) { Elevator elevator = new Elevator(); System.out.println(elevator.floor); elevator.moveUp(8); System.out.println(elevator.floor); elevator.moveDown(2); System.out.println(elevator.floor); } }

Method Call – object.method()��

new ��

1층��

public class Elevator { Elevator(int floor) { this.floor = floor; } public static void main(String[] args) { Elevator elevator = new Elevator(1); System.out.println(elevator.floor); elevator.moveUp(8); System.out.println(elevator.floor); elevator.moveDown(2); System.out.println(elevator.floor); } }

Constructor��

public class Elevator { }

Default Constructor��

public class Elevator { Elevator() { } }

Compiler��

public class Elevator { Elevator(int floor) { this.floor = floor; } }


public class Elevator { Elevator(int floor) { this.floor = floor; } }

Compiler��

public class Elevator { Elevator() { this.floor = 1; } Elevator(int floor) { this.floor = floor; } }


public class Elevator { Elevator() { this(1); } Elevator(int floor) { this.floor = floor; } }

this()��

Behavior��

moveUp()��

10층��

Behavior��

moveDown()��

1층��

Method Overloading�� public class Elevator { void moveUp() { moveUp(10); } void moveUp(int floor) { if (floor > 10 || this.floor >= floor) { return; } this.floor = floor; } void moveDown() { moveDown(1); } void moveDown(int floor) { if (floor <1 || this.floor <= floor) { return; } this.floor = floor; }

연습문제��

[6-1], [6-2], [6-3], [6-4], [6-5]��

p209��

static void moveUp(Elevator elevator) { elevator.moveUp(10); } public static void main(String[] args) { Elevator elevator1 = new Elevator(1); moveUp(elevator1); System.out.println("Elevator1 " + elevator1.floor); }

Call by Reference��

Stack Heap

Stack & Heap��

floor = 1 elevator1

Elevator Object

Stack Heap

Stack & Heap��

floor = 1 elevator1

Elevator Object

elevator

Stack Heap

Stack & Heap��

floor = 10 elevator1

Elevator Object

elevator

Stack Heap

Stack & Heap��


Elevator Object

static void swap(Elevator elevator1, Elevator elevator2) { Elevator temp = elevator1; elevator1 = elevator2; elevator2 = temp; System.out.println("Elevator1 " + elevator1.floor); System.out.println("Elevator2 " + elevator2.floor); } public static void main(String[] args) { Elevator elevator1 = new Elevator(1); Elevator elevator2 = new Elevator(10); swap(elevator1, elevator2); System.out.println("Elevator1 " + elevator1.floor); System.out.println("Elevator1 " + elevator2.floor); }

Swap��

Stack Heap

Stack & Heap��

floor = 1 elevator1

Elevator Object


Stack Heap

Stack & Heap��

floor = 1 elevator1

Elevator Object


elevator1

elevator2

Stack Heap

Stack & Heap��

floor = 1 elevator1

Elevator Object


elevator1

elevator2

Stack Heap

Stack & Heap��

floor = 1 elevator1

Elevator Object


Software

[NHN NEXT] Java 강의 - Week2