Java Academy Introduction to UML

7/28/2019 Java Academy Introduction to UML

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Introduction to UML

Java Center of Excellence



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Objectives

• Understand the basics of Unified ModelingLanguage (UML)

• Understand the commonly used UML diagrams




Your Expectations




Expectations

• Covered

– Basics of UML

– Commonly used UML Diagrams

• Not Covered– Modeling languages

– Detailed UML

– All UML Diagrams




Agenda

• Modeling• Unified Modeling Language

• UML Diagrams

– Class Diagram

– Sequence Diagram– State Diagram




Modeling Language

• Model– A model is a simplification of reality

– We build models so that we can better understand thesystem we are developing

– We build models of complex systems because we cannotcomprehend such a system in its entirety

• Mental Model

– Mental models are assumptions, generalizations, andimages.

– Mental Models must be questioned and communicated toensure that they are relevant and understood

– Communication must be based on a common language

• A Modeling Language helps to express MentalModels in a certain syntax


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Unified Modeling Language

• Unified Modeling Language is the language ornotation used to convey ideas in both the problemdomain (analysis) and the solution domain (design)

• Goals– To achieve uniform communication method for all

stakeholders

– To adress the issues of managing complex, mission-criticalsystems

– To model systems, from concept to executable artifact,using object-oriented techniques



Why UML?

• Standardized graphical notation for– Specifying, visualizing, constructing, and documentingsoftware systems

• Language can be used from general initial design tovery specific detailed design

• Increase understanding/communication of productto customers and developers

• Support for UML in many software packages today(e.g. Rational, Together J, Visio)



UML Diagrams

• UML Diagrams are divided into two differentviews of a system model

– Structural: Emphasize the static structure of thesystems using objects, attributes, operations andrelationships

– Behavioral: Emphasize on the dynamic behavior of thesystem by showing collaborations among objects andchanged to their states



UML Diagrams

• Structural– Class Diagram

– Component & Deployment Diagram

• Behavior– Activity Diagram

– Use Case Diagram

– Interaction Diagram

►Sequence Diagram

– State Machine Diagram



Class Diagram

• Main Building block of Object OrientedProgramming

• Represents the objects in the system and therelationships amongst them

• Classes are represented by a box having threesections

– Upper part holds the name of the Class

– Middle part holds the attributes or properties

– Bottom part holds the operations or functions



Class Diagram: Members

• Visibility– + denotes a public member

– # denotes a protected member

– - denotes a private member

– ~ denotes a package member

• Scope

– Instance: Refers to members and their values that arespecific to every instance of the object

– Classifier: Refers to members and their values that arecommon to all instance

►Static members in a class



Class Diagram: Instance Relationships

• Association– An association represents a family of links

– Can be named indicating the roles

– Is represented by a line between two objects




• Aggregation– It is a variant of a “has a” or association relationship

– More specific that an association; extends all thecharacteristics of an association

– Represents a “part-whole” relationship

– Represents that the contained classes do not have alifecycle dependency on the parent

► If the container is destroyed the contents are notdestroyed

– It is graphically represented by a hollow diamond on the

containing class end of the relationship




• Composition– It is a variant of a “owns a” or association relationship

– More specific that an aggregation; extends all thecharacteristics of an association

– Represents that the contained classes have a a lifecycle

dependency on the parent► If the container is destroyed the contents are also

destroyed

– It is graphically represented by a solid diamond on thecontaining class end of the relationship



Class Diagram: Class Relationships

• Generalization– Indicates that the sub-type is considered to be a

specialized form of the super-type

– Super-type is considered as the “Generalization” of sub-type

►Sub-type is considered as the “Specialization” of the super-type

– It is graphically represented by a hollow triangle on thesuper-type



Class Diagram: Class Relationships

• Realization– Indicates a relationship between two model elements,where the client realizes the behavior of the supplier

– It depicts a relationship between classes, interfaces,components and packages

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Class Diagram: General Relationships

• Dependency– Indicates a weaker form of relationship

– Indicates that a class uses another class at a point of time

– Exists if a contained class exists as a parameter or a

local variable in the container class– Is graphically represented by dotted line ending with an

arrow on the class that is contained or is used



Class Diagram: General Relationships

• Multiplicity– Relationships indicate that two classes make a referenceto each other

– Multiplicity helps in identification of multiplicityrelationship of instances

– Common Multiplicities are► 0..1

► 1

► 0..* or *

► 1..*



Sequence Diagram

• A type of Interaction Diagram• Describes how a process operates between

objects and in what order

• Represented by

– Parallel Vertical Lines depict object lifelines– Horizontal Lines depict messages transferred between

objects



Sequence Diagram



State Machine Diagram

• Provide an abstract description of behavior of asystem– Behavior is represented in a series of events that can

occur in one or many states

• Each diagram represents an object of a single

Class, tracking different states• Represented by

– States are represented as rounded rectangles, labeledwith names

– Transitions are represented by arrows, labeled with

events triggering the transition– Initial State is represented by Solid Circle

– Final State is represented by a Solid Circle inside of ahollow circle



State Machine Diagram



Questions

Java Academy Introduction to UML

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