When to use which creational pattern in LLD - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Choosing the right creational pattern for object creation

You need to create multiple instances of a complex object with many optional parameters. Which creational pattern is best suited?

A Prototype pattern to clone existing objects

B Singleton pattern to ensure only one instance is created

C Factory Method pattern to create objects based on a common interface

D Builder pattern to construct the object step-by-step with optional parameters

💡 Hint

Think about a pattern that helps build complex objects with many optional parts.

The Builder pattern is ideal for creating complex objects step-by-step, especially when many optional parameters exist. Singleton restricts to one instance, Factory Method focuses on object creation via subclasses, and Prototype clones existing objects.

🧠 Conceptual

intermediate

Ensuring a single instance across the system

You want to ensure that only one instance of a configuration manager exists throughout your application. Which creational pattern should you use?

A Builder pattern to build configuration step-by-step

B Singleton pattern to restrict instantiation to one object

C Factory Method pattern to create configuration objects

D Prototype pattern to clone the configuration manager

💡 Hint

Think about a pattern that restricts the number of instances to one.

The Singleton pattern ensures only one instance of a class exists and provides a global point of access to it. Prototype clones objects, Factory Method creates objects via subclasses, and Builder constructs complex objects stepwise.

❓ Architecture

advanced

Designing a system with interchangeable product families

You are designing a system that needs to create families of related objects without specifying their concrete classes. Which creational pattern fits best?

A Abstract Factory pattern to create related objects without specifying classes

B Builder pattern to construct objects step-by-step

C Prototype pattern to clone existing objects

D Singleton pattern to ensure one instance of each product

💡 Hint

Consider a pattern that creates families of related objects together.

The Abstract Factory pattern provides an interface to create families of related or dependent objects without specifying their concrete classes. Builder focuses on stepwise construction, Singleton restricts instances, and Prototype clones objects.

❓ tradeoff

advanced

Tradeoffs between Prototype and Factory Method

Which statement best describes a key tradeoff between using Prototype and Factory Method patterns?

A Factory Method clones objects which is faster; Prototype creates new objects via subclassing.

B Prototype restricts to one instance; Factory Method builds complex objects stepwise.

C Prototype requires cloning existing objects which can be faster but needs an initial instance; Factory Method creates new objects via subclassing but may be slower.

D Factory Method ensures only one instance; Prototype creates families of related objects.

💡 Hint

Think about cloning versus subclass-based creation.

Prototype clones existing objects which can be efficient but requires an initial object to clone. Factory Method creates new objects by subclassing and overriding creation methods, which can be more flexible but sometimes slower.

❓ scaling

expert

Scaling object creation in a distributed system

You have a distributed system where multiple services need to create instances of a complex object efficiently and consistently. Which creational pattern or combination is best to ensure scalability and consistency?

A Use Prototype pattern to clone objects locally and Abstract Factory to ensure consistent families across services

B Use Singleton pattern on each service to ensure one instance per service and Builder pattern to construct objects

C Use Factory Method pattern with centralized registry to create objects and Builder pattern for complex construction

D Use Builder pattern only, letting each service build objects independently without coordination

💡 Hint

Consider cloning for efficiency and abstract factories for consistency across services.

Prototype allows efficient cloning locally, reducing creation overhead. Abstract Factory ensures consistent creation of related object families across distributed services. Singleton per service limits instances locally but not globally. Factory Method with centralized registry can become a bottleneck. Builder alone lacks coordination for consistency.