UML Diagrams: Class Diagrams in Software Engineering
- 1. Class Diagram Designed by: Nadia Nazeer
- 2. Objectives Concept of class diagram Creating class diagram
- 3. Classes ClassName attributes operations A class is a description of a set of objects that share the same attributes, operations, relationships, and semantics. Graphically, a class is rendered as a rectangle, usually including its name, attributes, and operations in separate, designated compartments.
- 4. Class Names ClassName attributes operations The name of the class is the only required tag in the graphical representation of a class. It always appears in the top-most compartment.
- 5. Class Attributes Person name : String address : Address birthdate : Date ssn : Id An attribute is a named property of a class that describes the object being modeled. In the class diagram, attributes appear in the second compartment just below the name-compartment.
- 6. Class Attributes (Cont’d) Person name : String address : Address birthdate : Date / age : Date ssn : Id Attributes are usually listed in the form: attributeName : Type A derived attribute is one that can be computed from other attributes, but doesn’t actually exist. For example, a Person’s age can be computed from his birth date. A derived attribute is designated by a preceding ‘/’ as in: / age : Date
- 7. Class Attributes (Cont’d) Person + name : String # address : Address # birthdate : Date / age : Date - ssn : Id Attributes can be: + public # protected - private / derived
- 8. Class Operations Person name : String address : Address birthdate : Date ssn : Id eat sleep work play Operations describe the class behavior and appear in the third compartment.
- 9. Depicting Classes Person name : String birthdate : Date ssn : Id eat() sleep() work() play() When drawing a class, you needn’t show attributes and operation in every diagram. Person Person name address birthdate Person eat play Person
- 10. Class Responsibilities A class may also include its responsibilities in a class diagram. A responsibility is a contract or obligation of a class to perform a particular service. SmokeAlarm Responsibilities -- sound alert and notify guard station when smoke is detected. -- indicate battery state
- 11. Relationships In UML, object interconnections (logical or physical), are modeled as relationships. There are three kinds of relationships in UML: • dependencies • generalizations • associations
- 12. Dependency Relationships CourseSchedule add(c : Course) remove(c : Course) Course A dependency indicates a semantic relationship between two or more elements. The dependency from CourseSchedule to Course exists because Course is used in both the add and remove operations of CourseSchedule.
- 13. Generalization Relationships Person A generalization connects a subclass to its superclass. It denotes an inheritance of attributes and behavior from the superclass to the subclass and indicates a specialization in the subclass of the more general superclass. Student
- 14. Generalization Relationships (Cont’d) Student UML permits a class to inherit from multiple super classes, although some programming languages (e.g., Java) do not permit multiple inheritance. TeachingAssistant Employee
- 15. Association Relationships If two classes in a model need to communicate with each other, there must be link between them. An association denotes that link. Instructor Student
- 16. Association Relationships (Cont’d) We can indicate the multiplicity of an association by adding multiplicity adornments to the line denoting the association. The example indicates that a Student has one or more Instructors: Instructor Student 1..*
- 17. Association Relationships (Cont’d) The example indicates that every Instructor has one or more Students: Instructor Student 1..*
- 18. Association Relationships (Cont’d) We can also indicate the behavior of an object in an association (i.e., the role of an object) using role names. Instructor Student 1..* 1..* learns from teaches
- 19. Association Relationships (Cont’d) We can also name the association. Team Student membership 1..* 1..*
- 20. Association Relationships (Cont’d) We can specify dual associations. Team Student member of 1..* president of 1 1..* 1..*
- 21. Association Relationships (Cont’d) Associations can also be objects themselves, called link classes or an association classes. Warranty Product Registration modelNumber serialNumber warrentyCode
- 22. Example
- 23. Example
- 24. References http://agilemodeling.com/artifacts/ classDiagram.htm http://creately.com/diagram-type/article/ simple-guidelines-drawing-uml-class-diagrams http://www.tutorialspoint.com/uml/ uml_class_diagram.htm https://www.smartdraw.com/class-diagram/
- 25. For Requesting more Slid Share Visit nadianazeer5@gmail.com