Factory Method pattern in LLD - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Factory Method Purpose

What is the main purpose of the Factory Method pattern in software design?

A To create objects without specifying the exact class of object that will be created.

B To enforce a single instance of a class throughout the application.

C To provide a global point of access to a resource.

D To allow objects to communicate directly without intermediaries.

💡 Hint

Think about how the pattern helps in object creation and flexibility.

The Factory Method pattern lets a class defer instantiation to subclasses, enabling flexible and decoupled object creation without specifying exact classes.

❓ Architecture

intermediate

Identifying Factory Method Components

In the Factory Method pattern, which component is responsible for defining the interface for creating an object but lets subclasses decide which class to instantiate?

A Concrete Creator

B Product Interface

C Creator (Abstract Class or Interface)

D Concrete Product

💡 Hint

Consider which part declares the factory method but does not implement it.

The Creator defines the factory method interface but leaves the instantiation to subclasses (Concrete Creators).

❓ scaling

advanced

Scaling with Factory Method Pattern

You have a system that creates different types of notification senders (Email, SMS, Push). How does using the Factory Method pattern help when adding a new notification type?

A You must modify the existing Creator class to handle the new notification type.

B You only need to add a new Concrete Product and a Concrete Creator without changing existing code.

C You need to rewrite the entire notification sending logic to support the new type.

D You have to add conditional statements in all client code to support the new notification.

💡 Hint

Think about how Factory Method supports open/closed principle.

Factory Method allows adding new products by creating new subclasses without modifying existing code, supporting scalability and maintainability.

❓ tradeoff

advanced

Tradeoffs of Using Factory Method Pattern

What is a common tradeoff when using the Factory Method pattern in a system?

A It forces all object creation to happen in a single place, reducing modularity.

B It tightly couples the client code to concrete classes, reducing flexibility.

C It eliminates the need for inheritance, which can limit reuse.

D It increases the number of classes, which can make the system more complex to understand.

💡 Hint

Consider the impact on codebase size and complexity.

Factory Method increases the number of classes by requiring separate creator and product subclasses, which can add complexity.

❓ component

expert

Request Flow in Factory Method Pattern

Given a Factory Method pattern implementation, what is the correct sequence of steps when a client requests an object?

A 1, 2, 3, 4

B 2, 1, 3, 4

C 1, 3, 2, 4

D 3, 2, 1, 4

💡 Hint

Think about the natural order of method calls and object creation.

The client calls the factory method on the Creator, which delegates to the Concrete Creator to instantiate the product, then the client uses the product.