Factory vs Factory Method vs Abstract Factory: A Comprehensive Guide

Understanding the nuances between Factory, Factory Method, and Abstract Factory design patterns can be overwhelming. This article aims to clarify their differences, provide practical use cases, and offer Java examples to enhance your grasp of these patterns.

1. Understanding the Differences

All three patterns encapsulate object creation, but they vary in their implementation:

• Factory: Simplifies object creation by providing a single class responsible for instantiating objects of different types.
• Factory Method: Allows subclasses to customize the type of objects created during runtime without modifying the Factory interface.
• Abstract Factory: Provides a generic interface for creating families of related objects, ensuring type consistency.

2. When to Use Each Pattern

Factory: Use when you need to create fixed types of objects with straightforward creation logic.

Factory Method: Consider when you want to defer the decision of which object to create to subclasses and ensure consistent object creation through a common interface.

Abstract Factory: Ideal for creating families of related objects that must be mutually compatible and type-safe.

3. Java Examples

Factory

// FruitFactory class implementing Factory pattern for creating Apple and Orange objects
class FruitFactory {
    public Apple createApple() {
        return new Apple();
    }

    public Orange createOrange() {
        return new Orange();
    }
}

Factory Method

// FruitPicker abstract class implementing Factory Method pattern
abstract class FruitPicker {
    protected abstract Fruit createFruit();

    public void pickFruit() {
        Fruit fruit = createFruit();
        // Logic for processing the fruit
    }
}

// OrangePicker extending FruitPicker and overriding createFruit()
class OrangePicker extends FruitPicker {
    @Override
    protected Fruit createFruit() {
        return new Orange();
    }
}

Abstract Factory

// FruitFactory interface providing Abstract Factory pattern
interface FruitFactory {
    Fruit createFruit();
    Picker createPicker();
}

// AppleFactory implementing FruitFactory for Apple-specific objects
class AppleFactory implements FruitFactory {
    @Override
    public Fruit createFruit() {
        return new Apple();
    }

    @Override
    public Picker createPicker() {
        return new ApplePicker();
    }
}

In conclusion, Factory, Factory Method, and Abstract Factory patterns offer distinct approaches to object creation and ensure code flexibility and extensibility. By understanding their differences and use cases, you can effectively leverage these patterns in your software development projects.