Design Patterns Online Quiz

This blog post provides a set of 25 multiple-choice questions (MCQs) on software design patterns, an essential concept for software developers aiming to write reusable and maintainable code. These questions cover a range of patterns, including creational, structural, and behavioral types, providing a broad perspective on their applications and benefits in real-world software development. Test your understanding and deepen your knowledge of design patterns to improve your coding practices and enhance the design of your software projects.

1. Which design pattern is primarily used to separate an object's construction from its representation?

a) Builder

b) Factory Method

c) Singleton

d) Prototype

2. What pattern provides a way to access the elements of an aggregate object sequentially without exposing its underlying representation?

a) Observer

b) Iterator

c) Decorator

d) Composite

3. Which pattern defines a family of algorithms, encapsulates each one, and makes them interchangeable?

a) Strategy

b) Command

c) State

d) Adapter

4. What design pattern is used to ensure that a class has only one instance and provides a global point of access to it?

a) Singleton

b) Abstract Factory

c) Builder

d) Prototype

5. Which design pattern is used to transform a request into a stand-alone object that contains all information about the request?

a) Command

b) Adapter

c) Proxy

d) Flyweight

6. What pattern allows classes with incompatible interfaces to work together by wrapping its own interface around that of an already existing class?

a) Adapter

b) Bridge

c) Composite

d) Facade

7. Which design pattern provides a simplified interface to a complex system?

a) Facade

b) Mediator

c) Observer

d) Decorator

8. What is the intent of the Decorator pattern?

a) To ensure a class only has one instance

b) To add new functionalities to an object dynamically

c) To hide the complexities of a system and provide an interface to the client

d) To manage algorithms, relationships, and responsibilities between objects

9. In the context of the Observer pattern, what is the role of the 'Subject'?

a) To be aware of every detail of its observers

b) To notify its observers about any changes

c) To update the state of its observers

d) To maintain a list of commands

10. What pattern is often used to reduce memory usage by sharing part of an object's state across multiple objects?

a) Singleton

b) Flyweight

c) Builder

d) Prototype

11. What design pattern allows an object to alter its behavior when its internal state changes?

a) State

b) Strategy

c) Bridge

d) Command

12. Which pattern encapsulates a request as an object, thereby allowing for parameterization of clients with different requests?

a) Command

b) Adapter

c) Observer

d) Strategy

13. What pattern is used to provide a unified interface to a set of interfaces in a subsystem?

a) Mediator

b) Adapter

c) Facade

d) Proxy

14. Which pattern describes a group of objects that is treated the same way as a single instance of the same type of object?

a) Composite

b) Decorator

c) Chain of Responsibility

d) Flyweight

15. What is the role of the Proxy pattern?

a) To control access to another object

b) To extend the functionality of an object

c) To build a variety of objects from one prototype

d) To ensure there is only one instance of a class

16. Which design pattern can create a set of methods in the superclass that can be extended by subclasses?

a) Template Method

b) Observer

c) Decorator

d) Facade

17. What is the primary purpose of the Bridge pattern?

a) To separate an interface from its implementation

b) To ensure that only one object of a particular class is created

c) To provide a way to configure a class with one of many behaviors

d) To offer a simplified interface to a complex system

18. Which pattern allows you to change the behavior of an object by changing its class?

a) Proxy

b) Decorator

c) State

d) Strategy

19. In which pattern do classes that implement a system change the way they interact without changing their own behavior?

a) Mediator

b) Observer

c) Strategy

d) Bridge

20. What pattern involves a series of handlers processing an event one after another?

a) Chain of Responsibility

b) Command

c) Iterator

d) Composite

21. Which pattern helps in adding responsibilities to the object dynamically?

a) Decorator

b) Factory Method

c) Prototype

d) Builder

22. Which pattern defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified?

a) Observer

b) Mediator

c) Proxy

d) Singleton

23. Which pattern is typically used to construct a complex object step by step?

a) Abstract Factory

b) Builder

c) Prototype

d) Singleton

24. What is the main feature of the Prototype pattern?

a) It ensures that a class has just one instance.

b) It provides a way to copy an object without depending on its class.

c) It allows for the flexible addition of new functionality.

d) It manages algorithm families and makes them interchangeable.

25. How does the Abstract Factory pattern work?

a) It provides an interface for creating families of related objects without specifying their concrete classes.

b) It offers a way to encapsulate a group of individual factories.

c) It defers instantiation of a class to subclasses.

d) It encapsulates a request as an object.