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Chapter 1 Introduction to Modeling Java and UML
http://w3.im.knu.edu.tw/~joseph
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Agenda What is modeling? UML Modeling software systems with
UML Modeling process
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Introduction Why Java?
A good object-oriented programming language
Web-enabled enterprise computing (J2EE)
Excellent support for exception handling and concurrency
Other OO languages Small Talk, C++, Object Pascal, C#,
Python
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Goal of This Book Be able to
Communicate an understanding of OO modeling theory and practice to others
Communicate an understanding of UML notation to others
Critically review a wide variety of UML software models Use UML to create a detailed understanding of the
problem from the user’s perspective Use UML to visualize and document a balanced solution
using the full suite of Java technologies Use UML to describe other technologies and class
libraries
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What Is Modeling? A model is a simplification with a
purpose Use precisely defined notation to
describe and simplify a complex and interesting structure, phenomenon, or relationship
Real-world examples The solar system model Mathematical models
地軸傾斜
北極冬天沒陽光
南極夏天沒黑夜
以太陽系模型說明極地永晝與永夜以太陽系模型說明極地永晝與永夜
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What Is Modeling? (cont’d) Simplification
Less complex, more accessible Varying perspectives
Describe the system from different perspectives
Help developers manage complexity Common notation
To facilitate communication Allows developers to combine their efforts and
to work in parallel
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UML Unified Modeling Language A language for specifying,
visualizing, constructing, and documenting the artifacts of software systems
A set of precise notations Helps developers create ideas and
communicate them An open standard controlled by OMG
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UMLThe Basics Abstraction 抽象化，摘要
只要抓住重點，不必每樣細節都考究 A simplification or model of a complex concept,
process, or real-world object Help people understand something at an appro
priate level Different people would build different abstracti
ons for the same concept Highlight the characteristics and behavior of so
mething that is too complex to understand in its entirety
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UMLThe Basics Encapsulation 封裝
凸顯重要特質隱藏內部細節 Highlight the important aspects of an obj
ect Hide the cumbersome internal details of
the object Make the system easier to understand an
d to reuse Make a system more extendible
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UMLThe Basics
Object A particular and finite element in a large model
Visible or invisible Persistent or transient
State: describes characteristics and current condition
Behavior: defines the actions that other objects may perform on the object
Method: a service or responsibility that an object exposes to other objects
Each has a unique identifier Limited responsibility and cooperation
myCar : ToyotaTercel
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UMLThe Basics Class
A group of objects that have something in common
Captures a particular abstraction Provides a template for object creation Each objects created from a class is
identical in The type of data they can hold The type and number of objects they know about The logic for any behavior they provide
+attackKenDoll()
-name : String-rank : String#carryingRifle : Boolean
ToySoldier
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UMLThe Basics Relationships between objects
Dependency Association Aggregation Composition
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Dependency Short-term dependency An object may create another object as
part of a method, ask it to perform some function, and then forget about it
Customer
+ringUpFood()+processPayment()
Cashier
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Association An object keeps a reference to another
object and can call the object’s, methods as it needs them
An object may receive an object as a parameter to a configuration method and keep a reference to the object
CarPerson
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Aggregation An object is part of a greater whole The contained object may participate
in more than one aggregation relationship, and exists independently of the whole
ProjectTeam SoftwareDeveloper
* *
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Composition An object is owned by a greater whole The contained object may not participate in
more than one composition relationship and cannot exist independently of the whole
Engine SmallGear
1 *
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UMLThe Basics Navigability
The control relationship The arrow indicates direction of control
+startEngine()
Car
+getSpinSpeed()
Wheel
1 *
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UMLThe Basics Multiplicity
The number of relationships No default multiplicity
+go()+displayStatus()
CarPerson
1..* * +turnOn()
Engine
1 1 +spin()
SmallGear
1 *
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UMLThe Basics Interface
Defines a set of related behavior Does not specify the actual implementation
for the behavior Specify the signature of one or more methods
A class realizes an interface by implementing each method in the interface
SoundSimulator
+makeNoise()
<<interface>>INoiseMaker
1 *
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UMLThe Basics Polymorphism
Multiple implementation of a single abstraction
Abstraction are captured in classes and in interfaces
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Polymorphism Through Realization
SoundSimulator
+makeNoise()
<<interface>>INoiseMaker
1 *
+makeNoise()
Trumpet
+makeNoise()
Tiger
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Polymorphism Through Inheritance
SoundSimulator
1 *
+makeNoise()
Trumpet
+makeNoise()
Tiger
+makeNoise()
SimulationElement
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Modeling Software Systems with the UML UML enables building a single
coherent model that describes a software system from several perspectives Internal consistency Distinct views
Participants can use the same model and speak the same language throughout the development process
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The Customer’s Perspective Use case
Defines and describes a discrete way in which users get value from the system
Text description of each use case Including the details of the interactions
between the user and the system Activity diagram
Visual description of the interaction between the system and the user for a use case
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The Developer’s Perspective Class diagram
Defines and constrains a group of objects in detail Shows the state, behavior, and relationships
State chart Describe the state-dependent behavior for a class How an object responses to requests depending
on its internal configuration Package diagram
How different parts of a system depend on one another
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The Developer’s Perspective (cont’d) Sequence diagram
How objects interact with one another to provide the functionality
Indicates the order of the interaction Collaboration diagram
Revealing the relationship between objects
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Modeling Process1. The developers and customers use
the UML to understand the problem from the customer’s point of view
2. The developers use UML to understand the problem from their own point of view
3. The UML model is used as a resource by the implementers of the system
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Modeling Process (cont’d) Requirements gathering Analysis Technology selection Architecture Design and implementation
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Requirements Gathering Understand the problem from the
customer’s point of view Do NOT concern for technology or
system design In this process, developers create
Use case diagrams Text use case descriptions Activity diagrams
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Analysis Understand the problem from the
developer’s point of view Still do NOT concern for technology Discover the roles and responsibilities
that must be filled in the system In this process, developers create
Class diagrams Sequence diagrams Collaboration diagrams
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Technology Selection Categorize the system in terms of its
technological requirements Select the most appropriate technologies
to fulfill these well-defined needs Produce a high-level summary of the
technological requirements and a list of appropriate technologies for the system
No additional UML diagrams are produced
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Architecture Describe the system at high level Decompose the system into smaller
parts (subsystems) Highlight relationships between parts Hide details of each part In this process, developers create
Primary class diagrams Package diagrams
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Design and Implementation Design
Use all the results from the previous steps Create a model of objects that interact to
provide the system’s functionality The last chance to validate the solution
Implementation Write the code according to the design
