Explore the Factory Design Pattern and its implementation using Java 8 Lambda expressions

Ramesh Fadatare

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Feb 24, 2025

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Introduction

In this article, we will explore the Factory Design Pattern and its implementation using Java 8 Lambda expressions. The Factory Pattern falls under the Creational Design Pattern category, providing a structured way to instantiate objects dynamically.

Definition of Factory Design Pattern

“Define an interface for creating an object, but let subclasses decide which class to instantiate. Factory Method lets a class defer instantiation to subclasses.” — Head First Design Patterns

We will first implement the Factory Pattern without lambda expressions, then see how we can simplify it using Java 8 Lambda Expressions and Method References.

Factory Design Pattern: Traditional Implementation (Without Lambda Expressions)

Step 1: Create an Interface (Shape.java)

public interface Shape {
    void draw();
}

Step 2: Implement Concrete Shape Classes

Rectangle.java

public class Rectangle implements Shape {
    @Override
    public void draw() {
        System.out.println("Inside Rectangle::draw() method.");
    }
}

Square.java

public class Square implements Shape {
    @Override
    public void draw() {
        System.out.println("Inside Square::draw() method.");
    }
}

Circle.java

public class Circle implements Shape {
    @Override
    public void draw() {
        System.out.println("Inside Circle::draw() method.");
    }
}

Step 3: Define an Enum for Shape Types (ShapeType.java)

public enum ShapeType {
    CIRCLE, RECTANGLE, SQUARE;
}

Step 4: Implement the Factory Class (ShapeFactory.java)