UML Diagrams MCQs Questions With Answers – Part 11

April 19, 2025 John Howard

Test your knowledge and boost your confidence with these multiple-choice quizzes focused on UML diagrams, foundational software engineering concepts, and real-world best practices. Designed for students, developers, and exam candidates, these MCQs offer a quick and effective way to assess your understanding and sharpen your skills.

1. Which of these elements is not a relationship in UML?

A Association

B Aggregation

C Function

D Dependency

A function is an operation, not a relationship. The others are possible relationships between classes or objects.

2. What does aggregation in UML mean __________

A One completely belongs to the other

B A weak “part-whole” relationship

C Specialization

D An abstract class

Aggregation (white diamond) indicates that an element is part of a whole, but can exist independently.

3. What is the correct representation of an object in a UML object diagram?

A Rectangle with name and attributes underlined

B Rectangle with a black background

C Oval with messages

D Empty rectangle

Objects are represented like classes, but their name is underlined to indicate an instance. Example: :BankAccount

4. What does this diagram show?

A The Invoice class inherits from Payable

B Payable is an abstract class

C The Invoice class implements a Payable interface

D Invoice depends on Payable

The dashed line with a triangle implements (<|..) designates an interface implementation. Invoice must provide concrete behavior for pay().

5. In a class diagram, what is the difference between an interface and an abstract class?

A The interface can have attributes

B An abstract class can have an implementation

C The interface is instantiable

D No difference

An interface: 100% methods without bodies (to be implemented).
An abstract class: can have methods already implemented.

6. What notation is used to indicate that a class contains a collection of objects in a class diagram?

A A diamond

B A square with arrows

C A dashed line

D A solid line with multiplicity *

The multiplicity * indicates that a class can be associated with any number of objects from another class, meaning a collection relationship. Example:

7. In a use case diagram, what does an arrow pointing from the actor to a use case indicate?

A An inclusion

B An extension

C A return message

D An association

An arrow between an actor and a use case represents an association: the actor interacts with the use case, it is a participation relationship.

8. In a state transition diagram, what is a “final state”?

A A state where the process has not yet started

B A state where the process makes a decision

C A state where the object or process is finished

D A state where the system is waiting for user action

A final state indicates that the process is completed. It is represented by a black circle surrounded by a white circle in the diagram.

9. What does this sequence diagram model?

A The structure of a payment system

B The chronological flow of an order with payment

C The state transitions of the payment service

D The relational model of a database

The diagram shows the chronological order of interactions between objects (or components) in a purchasing scenario.

10. What is an “extension” in a use case diagram?

A A relationship between two actors

B A conditional variant of a use case

C A mandatory inclusion in all use cases

D A loop in a process

An extension in a use case diagram adds conditional behavior to a use case. It is represented by an arrow with <<extend>> indicating an extension at a specific moment. Example:

1. Which of these elements is not a relationship in UML?

2. What does aggregation in UML mean __________

3. What is the correct representation of an object in a UML object diagram?

4. What does this diagram show?

5. In a class diagram, what is the difference between an interface and an abstract class?

6. What notation is used to indicate that a class contains a collection of objects in a class diagram?

7. In a use case diagram, what does an arrow pointing from the actor to a use case indicate?

8. In a state transition diagram, what is a “final state”?

9. What does this sequence diagram model?

10. What is an “extension” in a use case diagram?

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