Unified Modeling Language (UML)

Unified Modeling Language (UML) is a modeling language in software engineering, which is used to visualize the design of the proposing system.

• In software development life cycle, it comes under the “documenting the program” phase.
  • UML is used to document the developing system; this documentation helps the end user to understand the whole project.
• It visualizes all the components used in the developed object-oriented software; it shows all the elements and its relation.

Class diagram:

Class diagram is a static model which represents the system’s static structure and its relationship using attributes, relationships, objects, and operations.

• The relationship between the classes in the class diagram is called association.
• It is represented by drawing a line called association path between classes and placing the labels in between the association path.
• The instance of one class can be associated with more than one instance of another class and it is referred as multiplicity.

Steps to create class diagram:

• Identify objects
• Identify the attributes and behaviors
• Draw association between the classes.

Representing the class diagram:

• Every class in the class diagram is represented using a rectangle.
• The rectangle is divided into three parts,
  • The first part contains the name of the class
  • The middle part contains the attributes and derived attributes
  • The last part contains the methods.

Attributes:

• Initially, identify the reasonable attributes for “CreditCard” class.
• The “CreditCard” contains the card number, card name, expiry date for card, and so on.
• So, let us take the followings are the attributes for “CreditCard” class.
  • “cardNo”
  • “name”
  • “cardExpiryDate”

Behaviors:

• Initially, identify the reasonable behaviors for “CreditCard” class.
• The “CreditCard” contains the “getCredit”, “getPurchase” and so on.
• So, let us take the followings are the behaviors for “CreditCard” class.
  • “getCredit()”
  • “getPurchase()”

The UML class diagram for credit card is shown below:

The "CreditCard" class is shown in the following class diagram:

Java: An Introduction to Problem Solving and Programming (8th Edition), Chapter 5, Problem 1E , additional homework tip 1

Explanation:

In the above diagram,

• The class name is "CreditCard".
• The "cardNo", "name", and "cardExpiryDate" are attributes of "CreditCard" class.
• The "getCredit()" and "getPurchase()" are methods or operation name of "CreditCard" class.
  • "getCredit()" method is used to gets the credit card amount from bank.
  • "getPurchase()" is used to purchase the products by using the credit card.

Examples of objects of this "CreditCard"class:

First object:

The first object is "customer1" for this "CreditCard" class is shown below:

Java: An Introduction to Problem Solving and Programming (8th Edition), Chapter 5, Problem 1E , additional homework tip 2

Explanation:

In the above diagram,

• The "customer1" object for "CreditCard" class.
• Assign the "cardNo" as "123456", "name" as "XXXX" and "cardExpiryDate" as "03/02/2001" are the attributes of the "CreditCard" class.

Second object:

The second object is "customer2" for this "CreditCard" class is shown below:

Java: An Introduction to Problem Solving and Programming (8th Edition), Chapter 5, Problem 1E , additional homework tip 3

Explanation:

In the above diagram,

• The "customer2" object for "CreditCard" class.
• Assign the "cardNo" as "234578", "name" as "YYYY" and "cardExpiryDate" as "12/11/2022" are the attributes of the "CreditCard" class.

Third object:

The third object is "customer3" for this "CreditCard" class is shown below:

Java: An Introduction to Problem Solving and Programming (8th Edition), Chapter 5, Problem 1E , additional homework tip 4

Explanation:

In the above diagram,

• The "customer3" object for "CreditCard" class.
• Assign the "cardNo" as "341579", "name" as "ZZZZ" and "cardExpiryDate" as "01/02/2010" are the attributes of the "CreditCard" class.