Factory Method Design Pattern

Overview

The Factory Method Design Pattern provides an interface for creating objects in a superclass but allows subclasses to alter the type of objects that will be created. It promotes loose coupling by delegating the instantiation logic to subclasses.

Key Characteristics

• Defines an interface for creating objects.
• Delegates the responsibility of instantiating objects to subclasses.
• Promotes the Open/Closed Principle by allowing new types to be added without modifying existing code.

Implementation

The following is an example of a Factory Method implementation in Java:

abstract class Product {
    abstract void use();
}

class ConcreteProductA extends Product {
    @Override
    void use() {
        System.out.println("Using Product A");
    }
}

class ConcreteProductB extends Product {
    @Override
    void use() {
        System.out.println("Using Product B");
    }
}

abstract class Creator {
    abstract Product createProduct();
}

class ConcreteCreatorA extends Creator {
    @Override
    Product createProduct() {
        return new ConcreteProductA();
    }
}

class ConcreteCreatorB extends Creator {
    @Override
    Product createProduct() {
        return new ConcreteProductB();
    }
}
    

When to Use

• When a class cannot anticipate the type of objects it needs to create.
• When a class wants its subclasses to specify the objects it creates.

Advantages

• Promotes loose coupling between client code and concrete classes.
• Makes the code more scalable and adheres to the Open/Closed Principle.

Disadvantages

• Can result in a more complex code structure due to additional classes.

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