交通大學資訓工程學系蔡文能 1 More about OOP 蔡文能 [email protected] [email protected] 交通大學資訊工程學系 2006/11/09 tsaiwn/java

交通大學資訓工程學系蔡文能

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More about OOP

蔡文能[email protected]@cs.nctu.edu.tw

交通大學資訊工程學系2006/11/09

http://www.csie.nctu.edu.tw/~tsaiwn/java/


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Agenda

• Other OO Languages

• OO tools– Other OO languages: Java, C#– CRC card– Façade Design Pattern– UML

http://www.csie.nctu.edu.tw/~tsaiwn/cpp




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Other O-O Languages (1/2)

• C++ (Java = C++--++)In fact, Java is very similar to C++, except:

• All user-defined types are classes• All objects are allocated from the heap and accessed through

reference variables, including Arrays• Individual entities in classes have access control modifiers

(private or public), rather than clauses• All inheritances are public; all functions are virtual except

final• No operator overloading; No destructor; No pointer type• Java has a second scoping mechanism, package scope,

which can be used in place of friends– All entities in all classes in a package that do not have access

control modifiers are visible throughout the package


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Other O-O Languages (2/2)

• C# ( 唸作 C-Sharp, by MicroSoft)– Based on C++ and Java– Adds two access modifiers, internal and protected internal– All class instances are heap dynamic (same as in Java)– Default constructors are available for all classes– Garbage collection is used for most heap objects, so destructors are rar

ely used– structs are lightweight classes that do not support inheritance– Common solution to need for access to data members: accessor metho

ds (getter and setter)– C# provides properties as a way of implementing getters and setters w

ithout requiring explicit method calls


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• An Abstract Data Type (ADT) is a user-defined data type that satisfies the following two conditions: (Encapsulation + Information Hiding)– The representation of, and operations on, objects of

the type are defined in a single syntactic unit; also, other program units can create objects of the type.

– The representation of objects of the type is hidden from the program units that use these objects, so the only operations (methods) possible are those provided in the type's definition which are known as interfaces.

ADT --- Data Abstraction


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OO featuresEncapsulationInformation Hiding The concept of abstraction is

fundamental in programming

Subprogram / function

process abstraction

ADT

Data abstractionSoftware Reuse

增加 :InheritancePolymorphism

抽象化的概念以前就有 : 函數 / 副程式


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認真看 class• C 語言的 struct 目的是把相關資料 group 在一起• class ( 類別 ) 就是原來的 struct with some regulations• class is a user-defined data type, 自訂的 , 抽象的• 所以 class 是 Abstract Data Type (ADT)• ADT 就是把 data 以及對這些 data 有關的動作 (method, 就

是 function) 一起封藏 (Encapsulate) 在一個程式單元 (program unit) 之內 , 例如 C++ 用 class 來封藏

• Class 可用來設計軟體元件 (Software Component)• Class 內的 data member/method member 存取控制 :

– private, protected, public (C++ 與 Java 寫法不同 )

• Constructor? Destructor? Default Constructor? …• Java 沒有 Destructor, 但有 finalize 函數


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Constructor 就是與 Class 同名的函數 Constructor 函數沒有 type, 不可以寫 return type Constructor 將在 object 被安排好記憶體後立即執行 , 所

以通常用來設定初值 (initial value) Student x; // 這樣會幫 x 安排一塊記憶體 , 並執行 x.Student( ); Student * p; // 這樣只有指標 , 沒有生出 Student, 不會執行

constructor, 要 p= new Student( ); 才會執行 constructor

Summary of Constructor in C++

Object 就是 Class 的一個 instance ( 案例 ); 就是變數啦 Constructor 可以不寫 , 此時等於有一個沒參數且不做事

的 Default constructor 只要寫了一個 Constructor, 則原先的 Default Constructo

r 就自動消失不能用了 Constructor 也可以寫很多個 , 自動依參數決定用哪個

此即 Function name overloading ( 函數名稱重複用 ) 的概念


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Student x; // 這樣只會幫 x 安排一個參考 (reference, 其實就是 C++ 的指標 )必須再用 x = new Student( ); // 才會生出物件

Student * p; // 這樣在 Java 是錯的

Summary of Constructor in Java


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OO tools

• There are many OO tools for Software Engineering ( 軟體工程 )

• OOA– CRC cards (Class-Responsibility-Collaborator)

• OOD– Class diagram, UML, Rational ROSE, …

• OOP– Languages support OOP: C++, Java, Ada, …


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OOA: CRC Cards• Step two: Write CRC cards and work through scenarios

– Class-Responsibility-Collaborator Cards (Cunningham and Beck)– Just 3x5 cards

Data fields (attributes) 寫在背面

•Although CRC is not part of UML, they add some very useful insights throughout a development.


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OOD: Object-Oriented Design

• Step one: Create a UML class diagram of your objects

• Step two: Create a detailed description of the services to be performed– Peter Coad's "I am a Count. I know how to

increment…"– Activity, sequence, or collaboration UML

diagrams


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Façade Design Pattern• Façade: defines a clean, high-level interface to a subsystem.

• Context: building easy-to-use and maintain subsystems

• Problem: Each class in the subsystem provides part of the subsystem’s functionality, clients has to know the inside, changes to the subsystem may require changes to the clients.

• Solution: Add an interface class (the façade class) that knows the structure of the subsystem and forwards requests…

• Consequences: no or less dependency of client from structure of subsystem, ideal for layered subsystems

Facade


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MDA-Model Driven Architecture?

• A New Way to Specify and Build Systems– 2001 年由 OMG 制定的新開發架構 (http://www.omg.o

rg)

– 以 UML Model( 塑模 ) 為基礎– 支援完整開發週期 : Analysis, Design, Implementation,

Deployment, Maintenance, Evolution & Integration with later systems ( 改進與後續整合 )

– 內建協同運作性及跨平台性– 降低開發初期成本及提高 ROI ( 投資報酬 )

– 可套用至你所使用的任何環境 :

• Programming language Network

• Operating System Middleware


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Unified Modeling Language

• There have been O-O gurus for many years• Three of them worked together to define UML

(“Three amigos”: Booch, Rumbaugh, Jacobson)• Has now been approved as a standard by the

Object Management Group (OMG)• Very powerful, many forms of notation

– It's even provable! (with OCL)

http://www.UML.org

amigos = friends

http://www.omg.org

(Object Constrain Language)


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So, What is UML?

• UML is a Unified Modeling Language• UML is a set of notations, not a single methodology• Modeling is a way of thinking about the problems using m

odels organized around the real world ideas.• Resulted from the convergence of notations from three lea

ding Object-Oriented methods:• Booch method (by Grady Booch)• OMT (by James Rumbaugh)• OOSE (by Ivar Jacobson)

• You can model 80% of most problems by using about 20% of the UML

UML is a “blueprint” for building complex software

軟體工程師共通的語言


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History of the UML( http://www.uml.org/ )

PublicFeedback

Web - June 1996 Web - June 1996 UML 0.9UML 0.9

Unified Method 0.8Unified Method 0.8OOPSLA 95OOPSLA 95

UML 1.0UML 1.0UML partnersUML partners

OMG Acceptance, Nov 1997Final submission to OMG, Sept 1997First submission to OMG, Jan 1997

OMG Acceptance, Nov 1997Final submission to OMG, Sept 1997First submission to OMG, Jan 1997

UML 1.1UML 1.1

UML 2.0UML 2.0Approved 2004Approved 2004

Minor revision 1999 Minor revision 1999 UML 1.3UML 1.3

UML 1.4UML 1.4Minor revision 2001Minor revision 2001

OOSEOther methods OMTBooch method

Minor revision 2003Minor revision 2003 UML 1.5UML 1.5

http://www.uml.org/


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UML 常用的 Diagrams

• Use case diagrams– Functional behavior of the system as seen by the user.

• Class diagrams– Static structure of the system: Objects, Attributes, and

Associations.• Activity diagrams

– Dynamic behavior of a system, in particular the workflow, i.e. a flowchart.

• Sequence diagrams – Dynamic behavior between actors and system objects.

• Statechart diagrams– Dynamic behavior of an individual object as FSM ( 有限狀態機 ).


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UML 12 Diagrams

• Behavior : – Use Case– Sequence– Collaboration– State Chart– Activity

• Structural:– Class– Component– Deployment– Object

• Model Management: – Packages (class diagram contains packages)– Subsystems (class diagram contains subsystems)– Models (class diagram contains models)


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UML Core Conventions• Rectangles are classes or instances

• Ovals are functions or use cases

• Types are denoted with non-underlined names SimpleWatch Firefighter

• Instances are denoted with an underlined names myWatch:SimpleWatch Joe:Firefighter

• Diagrams are higraphs– Nodes are entities (e.g. classes, states)

– Arcs are relationships among entities (e.g. sender/receiver)

– Containment represents belonging (e.g. use cases in package)

Higraphs are an extension to the familiar Directed Graph structure where nodes are connected by edges to other nodes. Nodes represent entities in some domain (in our case, classes, packages, methods, etc.).


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Use Case Diagram examples

WatchUserWatchRepairPerson

ReadTime

SetTime

ChangeBattery

Actor

Use case

PackageSimpleWatch

Use case diagrams represent the functionality of the systemfrom user’s point of view. ( 強調 what, 但暫不管 how)

A use case documents the interaction between the system user and the system. It is highly detailed in describing what is required but is free of most implementation details and constraints.


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Class Diagram : a simple Watch

Batteryload()

1

2

Timenow()

PushButtonstatepush()release()

1

1

1

1

1

2

blinkIdxblinkSeconds()blinkMinutes()blinkHours()stopBlinking()referesh()

LCDDisplay

SimpleWatch

Class

Association

Operations

Class diagrams represent the structure of the domain or system

Attributes

Multiplicity


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Sequence DiagramObject

MessageActivation

Sequence diagrams represent the behavior as interactionsIt shows sequence of events for a particular use case

blinkHours()blinkMinutes()

incrementMinutes()refresh()

commitNewTime()stopBlinking()

pressButton1()

pressButton2()

pressButtons1And2()

pressButton1()

:WatchUser :Time:LCDDisplay:SimpleWatch

Activation

Collaboration Diagram

Object diagram withnumbered messages

Sequence numbers of messages are nested by procedure call


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button1&2Pressed

button1&2Pressed

button1Pressed

button2Pressed

button2Pressed

button2Pressed

button1Pressed

button1&2Pressed IncrementMinutes

IncrementHours

BlinkHours

BlinkSeconds

BlinkMinutes

IncrementSeconds

StopBlinking

State chart Diagrams for the watchStateInitial state

Final state

Transition

Event

FSM: Finite State Machine


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Activity Diagrams• An activity diagram shows flow control within a system

• An activity diagram is a special case of a state chart diagram in which states are activities (“functions”)

• Two types of states: – Action state:

• Cannot be decomposed any further

• Happens “instantaneously” with respect to the level of abstraction used in the model

– Activity state: • Can be decomposed further

• The activity is modeled by another activity diagram

描述 Business process 或 use case 的操作流程 ; 像流程圖

HandleIncident

DocumentIncident

ArchiveIncident


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Classes in UML

• Classes describe objects– Behaviour (member function signature / implementation)

– Properties (attributes and associations)

– Association, aggregation, dependency, and inheritance relationships

– Multiplicity and navigation indicators

– Role names

• Objects described by classes collaborate– Class relations → object relations

– Dependencies between classes


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UML ClassClass name

Data members(attributes)

Instance methods

ArgumentsReturn typesClass method (static)

Data members, arguments and methods are specified byvisibility name : type

Visibility shown as+ public- private# protected


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Class AttributesAttributes are the instance data membersand class data members

Class data members (underlined) are shared between all instances(objects) of a given class

Data types shown after ":"

Visibility shown as+ public- private# protected

Attributecompartment

visibility name : type

Class name


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Class Operations (Interface)

Operations are the classmethods with their argumentand return types

Public (+) operations define theclass interface

Class methods (underlined) can only access to class datamembers, no need for a classinstance (object)

Operationscompartment


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Template Classes

Generic classes depending on parametrised types

Type parameter(s)

Operations compartmentas usual, but may havetype parameter instead ofconcrete type


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Class InheritanceBase class or super class

Derived class or subclass

Arrow shows directionof dependency (B inherits A)

→ B inherits A's interface, behaviour and data members

→ B can extend A, i.e. add newdata members or member functions

→ B depends on A,A knows nothing about B


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Multiple Inheritance (Java)

The derived class inheritsinterface, behaviour anddata members of all itsbase classes

Extension and overridingworks as before

B implements the interface A andis also a "countable" class since itinherits class Countable

extends

implements

class B extends Countable implements A { /*…*/ }


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A is associated with B

• A has a B

• A has a method that returns a B

• vice versa

• etc.


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Class FriendshipFriends are granted access to private data members andmember functionsFriendship is given to other classes, never taken

Friendship breaks data hiding, use carefully !

Friend is the only one who can touch your private!


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Recommended Book: UML Distilled

• Serious O-O designers DO use UML

• UML Distilled by Martin Fowler is a great practical introduction to UML

• Official UML book series published by Addison-Wesley

http://www.omg.org


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UML Tools

• Most complete tool: Rational Rose, http://www.rational.com

• Lots of others :– Together by Object International, – Borland Together 2006 http://www.togethersoft.com

– BOOST (Basic Object-Oriented Support Tool) by Noel Rappin, available on CD/CoWeb

– Argo-UML, ObjectPlant, Posiden, etc.


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Thank You!Thank You!謝謝捧場

[email protected]

蔡文能

http://www.csie.nctu.edu.tw/~tsaiwn/java/

Documents

交通大學資訓工程學系 蔡文能 1 More about OOP 蔡文能 [email protected] [email protected] 交通大學資訊工程學系 2006/11/09 tsaiwn/java

交通大學資訓工程學系蔡文能 1 More about OOP 蔡文能 [email protected] [email protected] 交通大學資訊工程學系 2006/11/09 tsaiwn/java