Unified Modeling Language

Transcription

1 Unified Modeling Language A Brief Introduction

2 History In the early 1990s, three common OO modeling approaches James Rumbaugh's Object-modeling technique (OMT) 2 Grady Booch's Booch method Ivar Jacobson s Object-Oriented Software Engineering (OOSE)

3 History (2) 1995: All three employed at Rational Software Known as The Three Amigos : Too many modeling languages slower adoption of OO Wanted a non-proprietary language using the best parts Formed an international consortium Result: Unified Modeling Language, UML Not a development method, just a language Used to build a system model Part of this model can be represented as various forms of diagrams

4 UML Diagram Types We will focus on class diagrams! 4

5 Usage Guidelines Why use class diagrams? 5 To design software before coding Create a broad structure, check that it is consistent and reasonable To help you understand existing code Create a structural overview Can be faster to construct and to understand a diagram than a long text describing the same thing How should they be used? Less is more Focus! Illustrate one coherent subsystem at a time Include only as much as you need

6 Simple Class Diagram General structure of a class: 6 elements: Object[] length: int ArrayList size() : int get(int amount): Object add(object element): Object set(int index, Object element): void Attributes Class Name Operations (methods) Static members: Underlined! Colors are not part of the standard added here for clarity!

7 Visibility Markers Visibility markers before names + # ~ / Public Protected Private Package Derived (computed from other attributes) Also, static methods or fields are underlined 7 elements: Object[] length: int ArrayList +size() : int +get(int amount): Object +add(object element): Object +set(int index, Object element): void

8 Interfaces General structure of an interface: Interface name in italics Marked with the <<interface>> stereotype 8 List <<interface>> +size(): int +get(int amount): Object +add(object element): Object +set(int index, Object element): void

9 Realization Class Relationships: Realization An interface is simply a description Classes realize the interface: Provide a concrete implementation Dashed arrow, unfilled arrowhead Members shown: Where they are declared for the first time Where they are implemented / overridden List <<interface>> 9 +size(): int +get(int amount): Object +add(object element): Object +set(int index, Object element): void LinkedList ArrayList SkipList head: Object tail: LinkedList +size() : int elements: Object[] length: int +size() : int +get(int amount): Object +add(object element): Object +set(int index,object element): void +size() : int

10 Generalization Class Relationship: Generalization (inheritance) List specializes Collection (adds new requirements, new methods) Collection generalizes List Ordinary line, unfilled arrowhead Collection <<interface>> 10 +size(): int +add(object element): Object +contains(object element): boolean List <<interface>> +get(int index): Object +set(int index, Object element): void

11 Generalization 2 Class Relationship: Generalization (inheritance) GraphicCircle specializes Circle Circle generalizes GraphicCircle Ordinary line, unfilled arrowhead Circle +x, y, r: double +getarea(): double 11 +outline, fill: Color GraphicCircle +draw(drawwindow): void

12 Composition Instance Relationship: Composition A hand is part of a person If we "remove" the person, its hands also removed Line with filled diamond 12 Person Hand May add multiplicity Every person has two hands, every hand is part of one person Person 1 2 Hand Omit fields/methods when they are not relevant!

13 Aggregation Instance Relationship: Aggregation 13 Alternative 1: In our model, a car is permanently linked to its wheels 1 0..* Car Wheel Alternative 2: In our model, we can buy new wheels, or even swap wheels between cars Wheels can exist without cars * Car Wheel

14 Association Instance Relationship: Association A person subscribes to zero or more magazines A magazine has zero or (hopefully) more subscribers The connection is not as close as between a car and its wheels 14 Person 0..* 0..* Magazine May name an association (or composition / aggregation) Person 0..* subscribes 0..* Magazine

15 Other UML Diagrams 15