Skip to main content

Creating Class Diagrams with Umbrello 5: Guide

Table of Contents​

  1. Introduction to UML Class Diagrams
  2. Understanding Class Diagram Components
  3. Problem Statement: Credit Card System
  4. Installation and Setup
  5. Creating Your First Class Diagram
  6. Building the Class Structure
  7. Implementing Relationships

1. Introduction to UML Class Diagrams​

What are Class Diagrams?​

Class diagrams are the backbone of Object-Oriented modeling. They show:

  • Static structure of a system
  • Classes and their features
  • Relationships between elements
  • Inheritance hierarchies
  • Multiplicity and navigation

Why Use Class Diagrams?​

  • Visualize class structures
  • Plan application structure before coding
  • Document existing systems
  • Communicate designs between team members
  • Model database schemas

2. Understanding Class Diagram Components​

Classes​

A class represents a template for objects and consists of:

  • Name (top compartment)
  • Attributes (middle compartment)
  • Operations (bottom compartment)

Visibility Modifiers​

+ Public: Accessible from any class
- Private: Only accessible within the class
# Protected: Accessible in class and its subclasses
~ Package: Accessible within the same package

Relationships Types​

  1. Association: Basic relationship between classes

    • Unidirectional: One-way relationship
    • Bidirectional: Two-way relationship

  2. Aggregation: Weak "whole-part" relationship

    • Parts can exist independently
    • Shown with hollow diamond

  3. Composition: Strong "whole-part" relationship

    • Parts cannot exist without the whole
    • Shown with filled diamond

  4. Inheritance: "is-a" relationship

    • Shown with hollow triangle
    • Points to parent class

  5. Implementation: Class implementing interface

    • Shown with dashed line and hollow triangle
    • Points to interface

Multiplicity​

  • 1: Exactly one
  • *: Zero or more
  • 1..*: One or more
  • 0..1: Zero or one
  • n: Specific number
  • n..m: Range of numbers

3. Problem Statement: Credit Card System​

System Overview​

Creating a credit card management system that handles:

  • 6.5 million cardholders
  • 500,000 retailers
  • Various retail types (hotels, shops, etc.)
  • Transaction processing
  • Statement generation

Class Diagram

Key Requirements​

  1. Transaction Processing

    • Validate transactions over $50
    • Generate two-part vouchers
    • Track transaction status

  2. User Management

    • Store cardholder information
    • Manage retailer details
    • Handle credit limits

  3. Reporting

    • Generate monthly statements
    • Track transaction history
    • Monitor credit usage

4. Installation and Setup​

Prerequisites​

  • Linux/Windows operating system
  • Umbrello 5 installed
  • Basic understanding of UML concepts
  • Familiarity with object-oriented programming

Environment Setup​

  1. Launch Umbrello from terminal:
umbrello5
  1. Configure initial workspace:
    • Maximize window for better visibility
    • Arrange toolbars as needed
    • Enable grid view for alignment (optional)

5. Creating Your First Class Diagram​

Step 1: Create New Diagram​

  1. Click File → New
  2. Name project "Credit Card System"
  3. Select "Class Diagram" from available options

Create New Class Diagram

Tip: Use meaningful project names that reflect your system's purpose

Name Diagram

6. Building the Class Structure​

Creating the CreditCardCompany Class​

  1. Add Class
    • Right Click your mouse
    • From New --> Class
    • Name it "CreditCardCompany"

Create New Class Name Class

  1. Configure Class Properties
    • Right-click on the class → Properties

Open Properties

  1. Add Attributes

    - companyName: string (private)
    - transactionThreshold: float (private)
    - minCreditLimit: float (private)

    For each attribute:

    • Click "New Attribute"
    • Set name, type, visibility

Add Attributes Add Attribute Properties

Important: Choose appropriate visibility modifiers based on encapsulation principles

  1. Add Operations

    + checkCredit(): boolean
    + authorizeTransaction(): boolean
    + generateMonthlyStatement()

    For each operation:

    • Click "New Operation"
    • Set name, return type, visibility
    • Click Apply and then OK

Add Operations Add Operation Properties Add More Operations

Creating the CardHolder Class​

  1. Add Class Structure

    Class: CardHolder
    Attributes:
    - cardHolderId: string
    - name: string
    - creditLimit: float
    - cardNumber: string

    Operations:
    + makePayment()
    + getCreditStatus(): boolean
    + viewStatement()

  2. Configure Class Properties

    • Set proper visibility for attributes
    • Add validation methods
    • Configure relationships

Creating the Transaction Class​

  1. Define Transaction Structure 
    Class: Transaction
    Attributes:
    - transactionId: string
    - amount: float
    - date: Date
    - status: string
    - needsAuthorization: boolean

    Operations:
    + authorize(): boolean
    + createVoucher()
    + checkThreshold(): boolean

Add More Classes After Adding All Classes

7. Implementing Relationships​

Creating Class Relationships​

  1. Composition Relationships
    • CreditCardCompany to CardHolder (1 to 6.5M)
    Steps for each:
    • Select composition tool
    • Click source class
    • Drag to target class
    • Configure multiplicity

Select Composition 2. Setting Multiplicities

  • Click on relationship line
  • Open properties
  • Set source and target multiplicities
  • Configure navigation

Select Component and Open Properties Add Multiplicity

  1. Add More Association and Multiplicity Add Association Add Multiplicity

Saving and Exporting​

Saving Your Work​

  1. Go to File → Save As
  2. Choose a location and filename
  3. Select .xmi format

Printing or Exporting​

  1. Go to File → Print or Export
  2. Select desired format and options