1. OO programming and UML Design
Dr. Zhen Jiang
West Chester University

2. Outline Introduction to object and class Introduction to UML
Introduction to UML design

3. Introduction to object and class
Why OO programming?
Look at this picture carefully
You need to identify it from VERY similar pictures in the next slide

4. Introduction to object and class
Why OO programming?
Which one is shown before?
In the next slide, your partner will see the selected picture and other two pictures together. Write down something to help your partner to pick up the same picture correctly.

5. Introduction to object and class
Why OO programming?
Partner’s job

6. Introduction to object and class
Why OO programming?
Which one?

7. Introduction to object and class
Why OO programming?
From snapshot to the action

8. Introduction to object and class
Why OO programming?
From snapshot to the action 3 2 1

9. Introduction to object and class
What’s object
Identity
State
Behavior
Sequence Diagram
Statechart Diagram
Messages and methods
What’s class
Objects and Classes
Class Attributes
Operation (Method)
Interfaces
Interfaces and Implementation

10. What’s object
Fundamentals of Object-Oriented Programming

11. What’s object Conceptually, there are many ways to think of an object
something that can be seen or touched
a thing to which some action is directed
something that performs an action
The structure and behaviour of similar objects are defined in their common class
Objects have three properties: identity , state, and behaviour

12. Object Property 1: Identity
Identity is that property of an object which distinguishes it from all other objects
Most programming languages use variable names to refer to objects
Keep in mind, however, that an object may not have a name; Similarly, an object might have multiple names (aliases)
For this reason, there is a subtle distinction made between the concepts of "name" and "identity"

13. Object Property 2: State
The state of an object encompasses all of the descriptions of the object plus the current values of each of these descriptions

14. Object Property 3: Behaviour
Behaviour is how an object acts and reacts, in terms of its state changes and message passing
The state of an object represents the cumulative results of its behaviour
In object-oriented programming, a behaviour is invoked by sending a message to an object

15. Sequence Diagrams
A sequence diagram is an interaction diagram that focuses on the time ordering of messages
A vertical dashed line is used to represent the lifetime of an object (it’s the object’s lifeline)
A focus of control is a tall, thin rectangle that shows the period of time during which an object is performing an action

16. requestLdgClearance(r)
: Pilot
: ATC
: Radar
requestLdgClearance(r)
checkWeather
checkRunwayClear(r)
clear
clearance

17. Sequence

18. Statechart Diagram Captures dynamic behavior (event-oriented) Purpose
Model object lifecycle
Model reactive objects (user interfaces, devices, etc.)

20. Example Objects
There are many physical objects we can examine right in this room
each person is an object
any chair is not an object
each light bulb is an object
Any book is not an object
this room itself is an object (full or not)

21. See if the followings are objects or not:
Desk
Lamp
Person
Log
The Earth
Clock
Machine
Computer
Saving account
Answer: N, Y, Y, N, Y, Y, Y, Y, Y

22. Messages and Methods
A object executes a method when it sends/receives a message
For example, we can ask/tell a dog to sit by sending him the message "sit"
In object-oriented programming, objects send messages asking/telling others to perform behaviours -- those other objects invoke the method corresponding to the message in order to execute the desired behaviour

23. What’s class
A class describes the common structure (attributes/state) and behaviour of its instances
For example,
3.14, 2.71, and 5.5 can be classified as Floats
the following shapes can be classified as Circles

24. Classes and Objects An object is called an "instance" of a class
The terms instance and object are interchangeable
Creating an object from a class is often called instantiation
For example, there are many person objects in this room -- each person is an instance of the person class

25. Classes and objects
How would we describe the state, behaviour, and identity for each of these objects
We have looked at objects and we have seen that objects can be "classified" into classes
As programmers, we work with both classes and objects from those classes
For example, we might write a stack class and create multiple stack objects for use in our program

26. In a 2D drawing package, circles have a radius, a line thickness, a line colour, and a fill colour
Each individual circle (instance) drawn by the user has its own value for each attribute
The programmer writes a Circle class and the program instantiates a Circle object every time the user draws a Circle
a snowman made from 9 Circle instances

27. Class Attributes
An attribute is a named property of a class that describes the range of values that instances of the property may hold.(Booch,1999)
An attribute has a type that defines the type of its instances.
Only the object itself should be able to change the value of its attributes.
The values of the attributes define the state of the object

28. Operation (Methods)
An operation is the implementation of a service that can be requested from any object of the class to affect behavior (Booch, 1999)
An operation can be:
Question (does not change the value of the object)
Command (may change the value of the object)

29. Interfaces
An interface is a collection of operations that are used to specify a service of a class or a component (Booch, 1999)
An interface is a contract of related services and a set of conditions that must be true for the contract to be faithfully executed
Interfaces formalize polymorphism, they allow us to define polymorphism in a declarative way unrelated to implementation

30. Interface and Implementation
The class interface is its external (public) view
The class implementation is its internal (private) view
It is convenient to think of the interface as describing "what the objects of this class can do" and the implementation as "how the objects of this class do it"
The implementation of a class consists of all the "behind the scenes" operations defined in the interface of the class

31. Introduction to UML What’s UML Goals of UML Overview Class diagram
Class icon
Class relationship
Constraints
Other diagrams

32. UML: Unified Modeling Language
The Unified Modeling Language (UML) is an industry-standard language for specifying, visualizing, constructing, and documenting the artifacts of software systems
The UML definition was led by Grady Booch, Ivar Jacobson, and Jim Rumbaugh (all now at Rational Software)

33. UML simplifies the process of software design, making a "blueprint" for construction
In Essence: a tool used through the analysis and design phases of system development for expressing the constructs and relationships of complex systems
Target Usage: for building object-oriented and component-based systems

34. Goals of UML
1. Provide users with a ready-to-use, expressive visual modeling language so they can develop and exchange meaningful models
2. Provide extensibility and specialization mechanisms to extend the core concepts.
3. Be independent of particular programming languages and development processes.
4. Provide a formal basis for understanding the modeling language.
5. Encourage the growth of the Object-Oriented tools market.
6. Support higher-level development concepts such as collaborations, frameworks, patterns and components.
7. Integrate best practices.

35. Many free learning materials on the web Standard of UML
e.g.
Standard of UML
Some recommended texts on UML:
The Unified Modeling Language User Guide, [G. Booch, J. Rumbaugh, I. Jacobson, 2000]
UML Explained, [Kendall Scott, 2001]
Applying UML and Patterns 2nd Ed., [Craig Larman, 2002]
UML Distilled 2nd Ed., [Martin Fowler with K. Scott, 2000]
UML and C++, [R. Lee & W. Tepfenhart, 2001]

36. UML Overview
UML is a language for visualizing, specifying, constructing and documenting the artifacts of a software system
The artifacts might include requirements, architecture, design, source code, project plans, tests, prototypes, releases

37. Review something Object action action state1 state2
operations/methods
attributes: {attribute1,
attribute2}
structure
operation/method
attribute1
attribute2
value

38. Light Turn on/off On Off attributes: {True, False} True False
operations/methods:
Turn_on/off ( )
attributes: {True,
False}
structure
Turn_on
True
False
Turn_off
value

39. Class Diagram
Introduction
Class Icon
Relationships
Constraints

40. Introduction
The class diagram is fundamental to object-oriented programming
UML’s class diagrams capture the attributes and operations of each class as well the relationships that exist between classes

41. Class Icon Class Icon Hiding Details Visibility Notation
Attribute Specification
Operation Specification

42. Class Icon
The UML class icon is a rectangle with three compartments:
class name
class attributes
class operations
Attributes are specified in the following form:
object:class name
Circle
radius: float
center_x: int
center_y: int
area()
display()

43. Hiding Detail
You can optionally leave out the attributes, operations, or both in a class icon:
Circle
area()
display()
Circle
radius: float
center_x: int
center_y: int
Circle

44. UML Member Visibility Notation
UML has three visibility prefixes for members: + for public, # for protected, and – for private
e.g.
Circle
-radius: float
#area()
+display()

45. Full UML Attribute Specification
The full form of a UML attribute is as follows: [visibility] name [multiplicity] [: type] [= initial value] [{property}]
The property choices are changeable, addOnly, and frozen
Student Info
-id: string
-hasGraduated: bool = false

46. Full UML Operation Specification
The full form of a UML operation is as follows: [visibility] name [(parameter-list)] [:return-type] [{property}]
The property choices are sequential, concurrent, guarded, and isQuery
The full form of a UML parameter is: [direction] name : type [= default-value]
The direction choices are in, out, and inout

47. UML Class Relationships
A class relationship is a connection between two (or more) classes
The three most important class relationships are generalizations, associations, and aggregations
UML provides a graphical representation for each of the relationships using a different line type for each relationship

48. Class Relationships Generalization Association Association Class
Qualified Association
Ternary Association
Aggregation

49. Generalization
A generalization is a relationship between a general thing (superclass) and a more specific kind of that thing (subclass)
In the UML, generalization requires that objects of the subclass may be used anywhere an object of the superclass appears
Person
Student

50. Association
An association is a structural relationship that specifies that objects of one thing are connected to objects of another
Faculty
Student

51. Association Associations can be adorned with a name. Student Faculty
Teaching
Faculty
Student

52. Association Associations can be adorned with the roles. Student
teacher
Faculty
Student
learner

53. Association Associations can be adorned with the multiplicity. Faculty
Student 1
4..*

54. Association Class (relation attributes)
Each object of association class is one instance of relationship (link) in an association.
1..*
Faculty
Student
4..*
Course

55. Qualified Association
Qualified association relates two classes and a qualifier.
The qualifier is a special attribute that reduces the effective multiplicity of an association.
Directory
file name
File

56. Ternary Association
A ternary association is a structural relationship that specifies that objects of one thing are connected to objects of other two’s.
Project
Language
Developer

57. Aggregation
An aggregation is an association that represents whole/part relationship
The “whole” end of the association relationship is adorned with an open diamond shape (e.g. X is part of Y)
e.g. door:Door is part of car:Car X Y

58. Generalization, Aggregation, and Association
See if the following pairs of classes have generalization, aggregation or association
Faculty & student (as)
Hospital & doctor (as)
Door & Car (ag --<>)
Member & Organization (ag --<>)
People & student (ge <|-- )
Circle & point (ge --|>)
Department & Faculty (as)
Employee & Faculty (ge <|--)
Item & Printer (ge <|--)
Account & Checking account (ge <|-- )

59. Constraints Constraints on Object Constraints on Relations (Ordering)
General Constraints (Dependency)

60. UML class diagram is not object diagram
Customer
Loan
Bank
Bank-Loan
Other-Loan

61. Constraints on Object
The constraints restricts the values that objects can be.
Example: No employee’s salary can exceed the salary of the employee’s boss.
{salary <=boss.salary}
Employee
Salary
Employer
Salary

62. Constraints on Relations (Ordering)
{Order} indicates that the elements of the “many” end of an association have an explicit order that must be preserved.
{ordered}
Paper
Author 1
1..*

63. General Constraints (Dependency)
A dependency is a using relationship that states that a change in specification of one thing may affect another thing that uses it (but not necessarily the reverse)

64. General Constraints (Dependency)
Dependencies are often used when one class uses another class as an argument of the operation
Dependencies are also often used to express general constraints.
Aerodrome
checkRVR( r: Runway )
Runway
member-of
Person
Committee
{subset}
chair-of

65. UML Design UML class diagram is not object diagram.
How to describe the behaviors/actions of objects in UML class diagram?
UML class diagram is not data flow chart.
What kind of relationship is generalization?
How to keep the consistency of all the constraints?

66. UML class diagram is not object diagram
Should we add relation between Bank and Other-Loans?
Can Bank change Other-loans?
Instance of Loan and Other-Loans?
Other-Loan
Customer
Bank
Loan

67. How to describe the behaviors/actions of objects in UML class diagram
Person ?
Based on Use Case analysis
sSN
address
Student
Casher
Faculty
Customer

68. How to describe the behaviors/actions of objects in UML class diagram
Use case (stories): Each use case defines an interaction between an actor and the system
Use case
Use case
System
Use case
Use case

69. Scenarios of a use case Reception Check Waiting Failure Authorized?
Order
Waiting
Failure
Authorized
Success
Failure

70. How to describe the behaviors/actions of objects in UML class diagram
Basic idea:
behaviors + interface
For details, see in

71. UML class diagram is not data flow chart
bargain
Customer
Dealer
sign
buy
sell
report
Product
Manager
authorize

72. UML class diagram is not data flow chart
Customer, Dealer, and Manager
Bargain
Product
Customer
Salesman
Dealer
Manager

73. What kind of relationship is generalization
x: int
y: int
Position
Point
Position
Point
People ?
Student
radius: double
Circle
Rectangle
*Tip 4: Class A is a super class of class B if and only if any object of class B can also play the role as an object of class A.

74. How to keep the consistency of all the constraints1
1..6
Ticket-buyer
Traveler 1 1
0..6
Dependent 1

75. How to keep the consistency of all the constraints
0..1
0..1
Ticket-buyer
Traveler 1 1
0..6
Dependent
0..1

76. How to keep the consistency of all the constraints
Traveler
0..1 1
0..6
Ticket-buyer
Dependent