Wondershare EdrawMax - Class Diagram Lecture

Introduction

• Class Diagram: Used by developers to map out a system or software in static form.
• Helps figure out necessary classes, their functionality, and relationships with other system elements (operations, attributes, objects).

Benefits of Class Diagrams

• Simple and fast to read
• Provide a sense of orientation
• Foundation for creating systems
• Offer detailed insight into system structure
• Highlight specific code needed for execution
• Provide implementation-independent explanation of types used in a system

Class Diagram Notations

Class Notation

• Class Symbol: Represents a concept encapsulating state and behavior.
• Class Structure: Shown with a signature (Class Name, Attributes, Operations)

Class Name

• Shown in the first section (mandatory information).

Attributes

• Shown in the second section, Attribute: Type format.
• Define a class's values.

Operations/Methods

• Shown in the third section, Operation: Return Type format.
• Represent services the class provides.
• Method parameters are shown with type.

Visibility

• Public ( + ): Accessible by all.
• Private ( - ): Accessible only within the class.
• Protected ( # ): Accessible within the class and subclasses.
• Package ( ~ ): Accessible within the package.
• Derived ( / ): Derived attributes.
• Static: Underlined attributes or operations.

Relationships Between Classes

Bidirectional Association

• Represented by a straight line; shows awareness of each other.

Inheritance

• Indicates a parent-child relationship.

Realization

• One class implements the behavior of another.

Dependency

• One class depends on another (shown with a dashed arrow).

Aggregation

• Unilateral relationship; one class is part of another but can exist independently.

Composition

• Form of aggregation; one class depends on another, cannot exist independently.

Steps to Draw a Class Diagram

Step 1: Identify Class Names

• Identify primary objects of the system.

Step 2: Distinguish Relationships

• Determine relationships between classes/objects. Look for commonalities and abstractions.

Step 3: Create Structure

• Add class names, link with appropriate connectors, add attributes and methods.
• Use EdrawMax: File > New > Software & Database > Software Development > UML Modeling > New Drawing Sheet.

UML Class Diagram Library

• Drag and drop required shapes onto the drawing pane.
• Change names accordingly.
• Continue building the diagram, adding attributes, operations, and relationship symbols.

Customization

• Add text: Home tab > Text option.
• Fill colors: Theme option on the right side of the page.
• Fit to drawing: Page Layout tab > Fit to Drawing.

Diagram Elements

• Class: Blueprint for an object.
• Attributes: Define a class's values.
• Association: Relationship between classes.
• Multiplicity: Determines the number of attribute occurrences.
• Operations: How a class interacts with data.
• Aggregation: Unilateral relationship between classes.
• Role Model: Instances of classes in more detail.
• Abstract Class: Template definition of methods and variables; may contain abstract methods.
• Generalization Relationship: Child model element is based on a parent model element.

Examples of Class Diagrams in EdrawMax

• Java API UML Class Diagram
• Domain Model UML Class Diagram

Conclusion

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• Links provided for EdrawMax online or software download.