Introduction to Modeling Java and UML

Chapter 1 Introduction to Modeling Java and UML 鄧姚文 [email_address] http://w3.im.knu.edu.tw/~joseph

Agenda What is modeling? UML Modeling software systems with UML Modeling process

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

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

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

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

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

UML The 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 appropriate level Different people would build different abstractions for the same concept Highlight the characteristics and behavior of something that is too complex to understand in its entirety

UML The Basics Encapsulation 封裝凸顯重要特質隱藏內部細節 Highlight the important aspects of an object Hide the cumbersome internal details of the object Make the system easier to understand and to reuse Make a system more extendible

UML The 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

UML The 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

UML The Basics Relationships between objects Dependency Association Aggregation Composition

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

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

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

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

UML The Basics Navigability The control relationship The arrow indicates direction of control

UML The Basics Multiplicity The number of relationships No default multiplicity

UML The 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

UML The Basics Polymorphism Multiple implementation of a single abstraction Abstraction are captured in classes and in interfaces

Polymorphism Through Realization

Polymorphism Through Inheritance

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

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

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

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

Modeling Process The developers and customers use the UML to understand the problem from the customer’s point of view The developers use UML to understand the problem from their own point of view The UML model is used as a resource by the implementers of the system

Modeling Process (cont’d) Requirements gathering Analysis Technology selection Architecture Design and implementation

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

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

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

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

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

Introduction to Modeling Java and UML

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Introduction to Modeling Java and UML