Master Object-Oriented Design Patterns: Enhance Your Programming Skills

Question 1

What is a potential consequence of violating the Liskov Substitution Principle (LSP) in object-oriented software design?

Accepted Answer

Reduced maintainability

Answer

Increased flexibility

Answer

Improved performance

Answer

Enhanced security

Question 2

In the Observer design pattern, how does the publisher communicate with its subscribers?

Accepted Answer

The publisher broadcasts an event to all subscribers, who respond to it independently.

Answer

The publisher delegates the handling of an event to a single subscriber, which then notifies interested parties.

Answer

The publisher sends individual updates to each subscriber.

Answer

The publisher only notifies subscribers that are currently active.

Question 3

What is the primary purpose of the Singleton design pattern?

Accepted Answer

To enforce the creation of only one instance of a class.

Answer

To provide global access to data.

Answer

To decouple objects and their dependencies.

Answer

To simplify creation of complex objects.

Question 4

Which key benefit is provided by the Observer design pattern?

Accepted Answer

Loose coupling between objects.

Answer

Enhanced performance.

Answer

Simplified debugging.

Answer

Reduced memory consumption.

Question 5

In object-oriented programming, how do classes and objects differ?

Accepted Answer

A class is a blueprint, while an object is an instance of the class.

Answer

An object is a blueprint, while a class is an instance of the object.

Answer

Classes and objects are identical.

Answer

Objects can exist independently of classes.

Question 6

Which responsibility does NOT belong to the Factory Method?

Accepted Answer

Managing object lifecycle

Answer

Creating objects

Answer

Encapsulating object creation logic

Answer

Providing a single point of access to objects

Question 7

Which design pattern is best suited for creating a hierarchy of related objects?

Accepted Answer

Composite

Answer

Strategy

Answer

Decorator

Answer

Builder

Question 8

Which design pattern defines an interface for creating objects, but lets subclasses decide which class to instantiate?

Accepted Answer

Factory Method

Answer

Singleton

Answer

Observer

Answer

Adapter

Question 9

Which design pattern ensures that only one instance of a class exists and provides a global point of access to it?

Accepted Answer

Singleton

Answer

Factory Method

Answer

Observer

Answer

Command

Question 10

Which design pattern defines a one-to-many dependency between objects, where changes in one object automatically update all its dependents?

Accepted Answer

Observer

Answer

Factory Method

Answer

Singleton

Answer

Strategy

Question 11

Which design pattern encapsulates a set of algorithms, allowing them to be added and removed dynamically without affecting the client code?

Accepted Answer

Strategy

Answer

Observer

Answer

Adapter

Answer

Mediator

Question 12

Which design pattern allows adding additional functionality to an object by wrapping it with another object that provides the extra functionality?

Accepted Answer

Decorator

Answer

Observer

Answer

Adapter

Answer

Chain of Responsibility

Question 13

Which design pattern allows composing objects into tree structures, treating individual objects and compositions of objects uniformly?

Accepted Answer

Composite

Answer

Factory Method

Answer

State

Answer

Memento

Question 14

Which design pattern defines a series of steps, including conditional steps, that define an algorithm's workflow?

Accepted Answer

Template Method

Answer

Strategy

Answer

Visitor

Answer

Interpreter

Question 15

Which design pattern provides a way to save and restore the state of an object without exposing its internal structure?

Accepted Answer

Memento

Answer

Visitor

Answer

Strategy

Answer

Proxy

Question 16

Which design pattern encapsulates a request as an object, allowing it to be parameterized, queued, logged, or undone?

Accepted Answer

Command

Answer

Memento

Answer

Observer

Answer

Builder

Question 17

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

Accepted Answer

Strategy

Answer

Factory Method

Answer

Singleton

Answer

Decorator

Question 18

Which design pattern allows you to represent part-whole hierarchies and compose objects into tree structures?

Accepted Answer

Composite

Answer

State

Answer

Decorator

Answer

Observer

Question 19

Which design pattern is used to control access to an object and ensures that only specified clients can access it?

Accepted Answer

Proxy

Answer

Facade

Answer

Adapter

Answer

Decorator

Question 20

Which design pattern allows you to encapsulate complex code and provide a simpler interface for interacting with it?

Accepted Answer

Facade

Answer

Proxy

Answer

Strategy

Answer

Builder

Question 21

Which design pattern is used to define a mapping between an object model and a database relational model?

Accepted Answer

Data Mapper

Answer

Builder

Answer

Strategy

Answer

Observer

Question 22

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

Accepted Answer

Observer

Answer

Adapter

Answer

Strategy

Answer

Proxy

Question 23

What is the main purpose of the Decorator pattern?

Accepted Answer

Attach additional responsibilities to an object dynamically.

Answer

Provide a flexible alternative to subclassing.

Answer

Create objects that can be composed into larger structures.

Answer

Control access to an object.

Question 24

Identify the option that does NOT represent a benefit of using design patterns.

Accepted Answer

Increased code complexity

Answer

Improved code reusability

Answer

Reduced development time

Answer

Enhanced code maintainability

Question 25

Name the design pattern that ensures only one instance of a class exists.

Accepted Answer

Singleton

Answer

Factory method

Answer

Observer

Answer

Builder

Question 26

In the observer pattern, which class is responsible for notifying observers about changes?

Accepted Answer

Subject

Answer

Observer

Answer

Factory

Answer

Client

Question 27

Which characteristic is NOT essential for an effective design pattern?

Accepted Answer

Platform-dependence

Answer

Generality

Answer

Reusability

Answer

Simplicity

Question 28

How does the Builder design pattern differ from the Factory Method pattern?

Accepted Answer

It allows for the step-by-step construction of complex objects.

Answer

It ensures that only one instance of a class is instantiated.

Answer

It does not differ from the Factory Method pattern.

Answer

It simplifies object creation by encapsulating it in a single method.

Question 29

Which design pattern is most suitable for implementing a system of loosely coupled components that can be easily replaced or extended?

Accepted Answer

Strategy

Answer

Singleton

Answer

Factory Method

Answer

Decorator

Question 30

Identify the key advantage of using the Decorator design pattern.

Accepted Answer

It allows for the dynamic modification of an object's behavior at runtime.

Answer

It simplifies the creation of new classes by composing existing ones.

Answer

It improves code readability by separating concerns.

Answer

It ensures that only one instance of a class is instantiated.

Question 31

How does the Observer pattern facilitate communication between objects?

Accepted Answer

By defining a one-to-many dependency where objects are notified of changes in a subject object's state.

Answer

By creating a hierarchical structure of objects.

Answer

By using a central registry to manage object interactions.

Answer

By implementing a message-passing mechanism.

Question 32

How does the Observer pattern promote loose coupling between objects?

Accepted Answer

By allowing objects to communicate without direct references

Answer

By enforcing a rigid hierarchy between observer and observable objects

Answer

By limiting the number of observers that can be attached to an observable object

Question 33

Which design pattern defines an interface or abstract class that provides a generic interface for creating objects, while allowing subclasses to specify the type of objects to be instantiated?

Accepted Answer

Factory Method

Answer

Strategy

Answer

Singleton

Answer

Observer

Question 34

Which design pattern ensures the creation of a single instance of an object and provides a global point of access to that object?

Accepted Answer

Singleton

Answer

Observer

Answer

Factory Method

Question 35

Which design pattern is used to define a one-to-many dependency between two objects, where one object (observer) depends on another object (subject) and is notified when the latter's state changes?

Accepted Answer

Observer

Answer

Singleton

Answer

Mediator

Answer

Factory Method

Question 36

Which design pattern provides an interface to a set of related objects without exposing the underlying implementation, allowing for the composition of objects into tree structures?

Accepted Answer

Composite

Answer

Decorator

Answer

Factory Method

Question 37

Which design pattern defines a family of algorithms that can be used interchangeably, providing the flexibility to switch between them at runtime without affecting the client code that uses them?

Accepted Answer

Strategy

Answer

Adapter

Answer

Singleton

Answer

Decorator

Question 38

Which design pattern helps to separate the interface of an object from its implementation, allowing for the independent development and modification of both?

Accepted Answer

Bridge

Answer

Singleton

Answer

Adapter

Answer

Decorator

Question 39

Which design pattern defines a collection of objects that share a common interface and provides a way to iterate through them without exposing their underlying representation?

Accepted Answer

Iterator

Answer

Composite

Answer

Visitor

Answer

Singleton

Question 40

Which design pattern provides a mechanism to define and execute operations against a collection of objects without specifying their concrete classes?

Accepted Answer

Visitor

Answer

Iterator

Answer

Observer

Answer

Strategy

Question 41

Which design pattern allows for the creation of a series of linked objects, enabling the passing of requests along a chain of responsibility for flexible request handling?

Accepted Answer

Chain of Responsibility

Answer

Decorator

Answer

Composite

Question 42

Which design pattern ensures that a class has only one instance, guaranteeing a single point of access to its functionality?

Accepted Answer

Singleton

Answer

Observer

Answer

Factory Method

Question 43

Which design pattern provides an interface for creating objects while allowing subclasses to alter the type of objects that will be created?

Accepted Answer

Factory Method

Answer

Prototype

Answer

Singleton

Answer

Builder

Question 44

Which design pattern allows objects to subscribe to events published by other objects, enabling loose coupling and efficient communication between objects?

Accepted Answer

Observer

Answer

Singleton

Answer

Factory Method

Answer

Adapter

Question 45

Which design pattern is used to represent hierarchical relationships between objects, allowing for the composition of complex objects from simpler ones?

Accepted Answer

Composite

Answer

Observer

Answer

Strategy

Answer

Decorator

Question 46

Which design pattern is used to convert the interface of a class into another interface, making it compatible with other classes or systems?

Accepted Answer

Adapter

Answer

Proxy

Answer

Facade

Answer

Composite

Question 47

Which design pattern is used to decouple an abstraction from its implementation, allowing the implementation to be changed without affecting the clients that use the abstraction?

Accepted Answer

Bridge

Answer

Facade

Answer

Adapter

Answer

Decorator

Question 48

Which design pattern is used to add additional functionality to an object without changing its class?

Accepted Answer

Decorator

Answer

Proxy

Answer

Adapter

Answer

Bridge

Question 49

Which design pattern is used to provide a simplified interface to a complex system?

Accepted Answer

Facade

Answer

Bridge

Answer

Adapter

Answer

Decorator

Question 50

Which design pattern is used to create objects that represent the state of an object?

Accepted Answer

Memento

Answer

Singleton

Answer

Builder

Answer

Prototype

Question 51

Which design pattern is used to define a family of algorithms, encapsulate each one, and make them interchangeable?

Accepted Answer

Strategy

Answer

Observer

Answer

Factory Method