When to use which creational pattern in LLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main purpose of the Singleton pattern?

The Singleton pattern ensures a class has only one instance and provides a global point of access to it.

beginner

When should you use the Factory Method pattern?

Use Factory Method when you want to create objects without specifying the exact class, allowing subclasses to decide which class to instantiate.

intermediate

What problem does the Abstract Factory pattern solve?

Abstract Factory provides an interface to create families of related or dependent objects without specifying their concrete classes.

intermediate

When is the Builder pattern most useful?

Builder is useful when constructing complex objects step-by-step, especially when the object has many optional parts or configurations.

intermediate

Why use the Prototype pattern?

Prototype is used to create new objects by copying existing ones, which is helpful when object creation is costly or complex.

Which creational pattern ensures only one instance of a class exists?

A Builder

B Factory Method

C Singleton

D Prototype

Singleton pattern restricts instantiation of a class to one object.

Which pattern is best when you need to create families of related objects without specifying their concrete classes?

A Abstract Factory

B Builder

C Prototype

D Singleton

Abstract Factory provides interfaces for creating related objects without specifying their concrete classes.

When should you use the Builder pattern?

A To construct complex objects step-by-step

B To create a single instance globally

C To clone existing objects

D To decide which class to instantiate

Builder pattern helps build complex objects step-by-step, especially with many optional parts.

Which pattern allows subclasses to decide which class to instantiate?

A Singleton

B Prototype

C Builder

D Factory Method

Factory Method lets subclasses choose the class to instantiate.

What is a key benefit of the Prototype pattern?

A Ensures only one instance

B Creates objects by cloning existing ones

C Builds complex objects step-by-step

D Creates families of related objects

Prototype creates new objects by copying existing ones, saving creation cost.

Explain when to use the Singleton, Factory Method, and Builder patterns in simple terms.

Think about controlling instance count, choosing object types, and building complex objects.

Describe the difference between Abstract Factory and Prototype patterns and when each is appropriate.

Focus on object families vs cloning.