CMSC 132 Object Oriented Programming II Unified Modeling Language UML Department of Computer Science University of Maryland College Park UML Unified Modeling Language UML is a modeling language for Specifying Visualizing Constructing Documenting object oriented software Motivation Software growing larger complex Difficult to describe and analyze Use UML to help Visualize design of software Provide abstract model of software Goals Provide a software blueprint Simple yet clear abstraction for software Describe software design Clearly Concisely Correctly History of UML Started in 1994 Combines 3 leading OO methods OMT OOSE Booch James Rumbaugh Ivar Jacobson Grady Booch UML Diagrams UML provides a number of diagrams that Describe a model of all or part of system From a particular point of view With varying level of abstraction Using certain set of notations System Model 1 View 1 View 2 View 3 Model 2 Class Diagram Represents static structure of system A class diagram displays Information for class Relationships between classes Class Diagram Class Multiplicity 1 1 2 PushButton state push release Association SimpleWatch LCDDisplay blinkIdx blinkSeconds blinkMinutes blinkHours stopBlinking referesh 1 1 1 2 1 Battery load Time now Attributes Operations Class diagrams represent structure of system Class Diagrams Information for class contains Name State Behavior Class Diagram Class name is required Other information optional State behavior Types visibility UML Class Diagrams Java Code Different representation of same information Name state behavior of class Relationships between classes Should be able to derive one from the other Motivation UML Java Implement code based on design written in UML Java UML Create UML to document design of existing code Java UML Clock Example Java class Clock name state int seconds int minutes int hours behavior void start void adjustTime void reset Java Code Class Diagram Class Diagram Notation UML notation Type Visibility public type name preceded by colon prefix symbol private Types of relationships Generalization Inheritance Implementation Association Dependency Java UML Clock Example Java Clock class Clock name seconds int state minutes int private int seconds hours int private int minutes setTime void private int hours adjustTime void behavior reset void public void setTime public void adjustTime int value public void reset Java Code Class Diagram Generalization Denotes inheritance between classes Can view as is a relationship Example Lecturer is a person Lecturer extends Person class Types of generalization Subclass extends superclass Solid line ending in open triangle Class implements interface Dotted line ending in open triangle Generalization Example Inheritance Laptop Desktop PDA inherit state behavior from Computer Generalization Example Implementation Laptop interface DVDplayer Laptop implements DVDplayer interface Association Denotes interaction between two classes Example Lecturer teaches course Indicates relationship between Lecturer Course Lecturer Course Association w Navigation Navigation information Relationship between classes may be directional Only class A can send messages to class B Arrowhead indicates direction of relationship Example class Course Lecturer TheBoss class Lecturer Association w o Navigation Undirected edge Relationship between classes may be bi directional Direction of relationship may be unknown Examples class Course Lecturer TheBoss class Lecturer Course class class Foo class Bar Permanent Association Permanent structural association Class A contains reference to class B in data field Can view as has a relationship Also referred to as composition Example class A B x class B A has a B Temporary Association Dependency A transitory relationship between classes Always directed class A depends on B Indicates change in class B may affect class A Can view as uses a relationship Represented by dotted line with arrowhead Example A B A depends on B Dependency Dependence may be caused by Local variable Parameter Return value Example class A B foo B x B y new class B UML Examples Read UML class diagram Try to understand relationships Practice converting to from Java code Examples Computer disk organization Banking system Home heating system Printing system UML Example Computer System Try to read understand UML diagram CPU is associated with Controllers DiskDrive is associated with SCSIController SCSIController is a type of Controller UML Example Banking System Bank associated with Accounts Checking Savings MoneyMarket are type of Accounts UML Example Home Heating System Thermostat associated with has a Room Thermostat associated with has a Heater ElectricHeater is a specialized Heater AubeTH101D is a specialized Thermostat UML Example Library System Try to read understand UML diagram Books are associated with has some Pages Patron Shelf depend on temporarily use Books UML Java Computer System UML Java class Controller class SCSIController extends Controller UML Java Computer System UML Java Design code using all available information in UML UML Java Computer System Java class CPU Controller myCtlrs class Controller CPU myCPU class SCSIController extends Controller DiskDrive myDrive 4 Class DiskDrive SCSIController mySCSI Java UML Printing System Java class Registry PrintQueue findQueue class PrintQueue List printJobs Printer myPrinter Registry myRegistry void newJob int length Resources getResource Java UML Printing System Java Class Printer Resources myResources Job curJob void print boolean busy boolean on class Job Job Registry r Java UML Printing System Java All together UML Tools Can automatically generate UML diagrams from code Code from UML diagrams Examples AmaterasUML Violet Amateras UML Editor Drag n drop classes into UML diagram Auto creates class w attributes methods Add links manually No directed associations Use undirected association directed dependency together Amateras UML Editor Eclipse Plugin Violet UML Editor Drag n drop classes into UML diagram Auto creates class w attributes methods Add links manually No undirected associations Use directed association in both directions instead Violet UML Editor Eclipse Plugin UML Summary UML modeling language Visually represents design of software system We focused on class diagrams Contents of a class Relationship between classes You should be able to Draw UML class diagram given Java code Write Java code given UML class diagram
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