![© Dr. Khalid Nazim S.A. B.E., M. Tech, MBA[IT], PhD, LMISTE, LMCSI, MIE
Associate Professor,
Department of Computer Science & Information,
Majmaah University, Az- Zulfi Campus, KSA.
CS 413: Software Modeling and Analysis](https://image.slidesharecdn.com/week13classdiagram-250327104843-d5865707/85/Class-diagram-and-its-importance-in-software-1-320.jpg)
![Class attributes
attributes (fields, instance variables)
visibility name : type [count] = default_value
1. visibility: + public
# protected
- private
~ package (default)
/ derived
2. underline static attributes
3. Derived attribute: not stored, but can
be computed from other attribute values
4. attribute example:
- balance : double = 0.00](https://image.slidesharecdn.com/week13classdiagram-250327104843-d5865707/85/Class-diagram-and-its-importance-in-software-11-320.jpg)
Class diagram and its importance in software
- 1. © Dr. Khalid Nazim S.A. B.E., M. Tech, MBA[IT], PhD, LMISTE, LMCSI, MIE Associate Professor, Department of Computer Science & Information, Majmaah University, Az- Zulfi Campus, KSA. CS 413: Software Modeling and Analysis
- 2. Week 13 Topics to be Discussed: What are class Diagrams? What is a class? CRC(Class, Responsibility, Collaborator) UML Class Diagram Notation How to draw Class Diagrams Relationships between classes Purpose of Class Diagrams Benefits of Class Diagrams Simple Examples
- 4. Design Phase Design : specifying the structure of how a software system will be written and function, without writing the complete implementation. A transition from "what" the system must do, to "how" the system will do it 1. What classes will we need to implement a system that meets our requirements? 2. What fields and methods will each class have? 3. How will the classes interact with each other?
- 5. Customer Account Opens account Knows name Knows address Account Manager Knows interest rate Knows balance Handles deposits Reports fraud to manager CRC (Class responsibility collaborator) A Class-Responsibility-Collaboration (CRC) card is a structured tool used in object-oriented software design. It captures essential information about a class, including its name, responsibilities, and collaborations with other classes. CRC cards facilitate collaborative discussions among team members and help in refining the design of software systems.
- 6. UML Class Diagrams What is a UML class diagram? UML class diagram: a picture of The classes in an OO system, Their fields and methods, Connections between the classes that interact or inherit from each other, Algorithmic details; how a particular behavior is implemented.
- 7. Class Diagrams Class diagrams are used when developing an object-oriented system model to show the classes in a system and the associations between these classes. An object class can be thought of as a general definition of one kind of system object. An association is a link between classes that indicates that there is some relationship between these classes. When you are developing models during the early stages of the software engineering process, objects represent something in the real world, such as a patient, a prescription, doctor, etc.
- 8. UML Notation for Classes ClassName The top compartment shows the class name. field1 … fieldn The middle compartment contains the declarations of the fields of the class. method1 … methodm The bottom compartment contains the declarations of the methods
- 9. How to Draw Class Diagrams Drawing class diagrams involves visualizing the structure of a system, including classes, their attributes, methods, and relationships. Step 1: Identify Classes: 1. Start by identifying the classes in the system. 2. A class represents a blueprint for objects and should encapsulate related attributes and methods. Step 2: List Attributes and Methods: 1. For each class, list its attributes (properties, fields) and methods (functions, operations). 2. Include information such as data types and visibility (public, private, protected). Step 3: Identify Relationships: 1. Determine the relationships between classes. 2. Common relationships include associations, aggregations, compositions, inheritance, and dependencies. 3. Understand the nature and multiplicity of these relationships. Step 4: Create Class Boxes: 1. Draw a rectangle (class box) for each class identified. 2. Place the class name in the top compartment of the box. 3. Divide the box into compartments for attributes and methods.
- 10. Step 5: Add Attributes and Methods: 1. Inside each class box, list the attributes and methods in their respective compartments. 2. Use visibility notations (+ for public, – for private, # for protected, ~ for package/default). Step 6: Draw Relationships: 1. Draw lines to represent relationships between classes. 2. Use arrows to indicate the direction of associations or dependencies. 3. Different line types or notations may be used for various relationships. Step 7: Label Relationships: 1. Label the relationships with multiplicity and role names if needed. 2. Multiplicity indicates the number of instances involved in the relationship, and role names clarify the role of each class in the relationship. Step 8: Review and Refine: 1. Review the class diagram to ensure it accurately represents the system’s structure and relationships. 2. Refine the diagram as needed based on feedback and requirements. How to Draw Class Diagrams
- 11. Class attributes attributes (fields, instance variables) visibility name : type [count] = default_value 1. visibility: + public # protected - private ~ package (default) / derived 2. underline static attributes 3. Derived attribute: not stored, but can be computed from other attribute values 4. attribute example: - balance : double = 0.00
- 12. Class Operations / Methods operations / methods visibility name (parameters) : return_type 1. visibility: + public # protected - private ~ package (default) 2. underline static methods 3. parameter types listed as (name: type) 4. omit return_type on constructors and when return type is void 5. method example: + distance(p1: Point, p2: Point): double
- 13. Comments represented as a folded note, attached to the appropriate class / method / etc. by a dashed line
- 15. Relationships between classes Generalization : An inheritance relationship, 1. Inheritance between classes 2. Interface implementation Association : A usage relationship 1. Dependency 2. Aggregation 3. Composition
- 16. Generalization Relationships Generalization (inheritance) relationships 1. hierarchies drawn top-down with arrows pointing upward to parent 2. line/arrow styles differ, based on whether parent is a(n): 1. class: solid line, black arrow 2. abstract class: solid line, white arrow 3. interface: dashed line, white arrow
- 17. Associational Relationships Associational (usage) relationships 1. Multiplicity : (how many are used) * ⇒ 0, 1, or more 1 ⇒ 1 exactly 2..4 ⇒ between 2 and 4, inclusive 3..* ⇒ 3 or more 2. Name : (what relationship the objects have) 3. Navigability : (direction)
- 18. one-to-one each student must carry exactly one ID card one-to-many one rectangle list can contain many rectangles Multiplicity of Associations
- 19. Association Types 1. aggregation: "is part of" symbolized by a clear white diamond. 2. composition: "is entirely made of" stronger version of aggregation the parts live and die with the whole. symbolized by a black diamond. 3. dependency: "uses temporarily" symbolized by dotted line often is an implementation detail, not an intrinsic part of that object's state 1 1 Car aggregation Engine Lottery Ticket Random dependency Page Book composition * 1
- 20. Purpose of Class Diagrams The main purpose of using class diagrams is: 1. This is the only UML that can appropriately depict various aspects of the OOPs concept. 2. Proper design and analysis of applications can be faster and efficient. 3. It is the base for deployment and component diagram. 4. It incorporates forward and reverse engineering.
- 21. Benefits of Class Diagrams 1. Clarity and Communication 2. Standardization 3. Facilitates Object-Oriented Design 4. Documentation and Maintenance 5. Support for Code Generation
- 22. Class Diagram : Simple Example
- 23. Class Diagram Example: 01 Aggregation – Order class contains OrderDetail classes. No arrows; info can flow in both directions
- 25. DVD Movie VHS Movie Video Game Rental Item Rental Invoice 1..* 1 Customer Checkout Screen 0..1 1 Simple Association Class Abstract Class Simple Aggregation Generalization Composition Multiplicity Class Diagram Example: 03: Video Store
- 27. Structural UML diagram provide a visual language for representing the static structure of a system, offering clarity and facilitating communication through class diagrams, object diagrams, package diagrams, and more. These diagrams offer insights into the relationships, dependencies, and organization of elements within a software system. UML Class Diagrams are a powerful tool in software engineering, offering significant advantages in clarity, standardization, and support for object-oriented design. However, it is essential to be aware of their limitations and use them in conjunction with other modeling techniques to achieve a comprehensive understanding of the system. Summary