Java Design Factory — Free Java Tutorial

TL;DR: Learn Java Design Factory in Java with a free, beginner-friendly tutorial, examples and practice for Indian students on Syllab.in.

Java Design Factory in Java

The Factory pattern provides a way to create objects without specifying the exact class. A factory method returns an instance of one of several possible classes depending on the input.

It promotes loose coupling — the caller does not need to know which concrete class is being created, only the interface/abstract type.

Simple Factory: one class with a static method that returns different subtypes. Factory Method Pattern: subclasses decide which class to instantiate. Abstract Factory: family of related factories.

Common uses: database drivers (DriverManager.getConnection()), UI components for different platforms, parser creation (JSON vs XML), payment processor selection.

interface Animal { void speak(); }
class Dog implements Animal { public void speak() { System.out.println("Woof"); } }
class Cat implements Animal { public void speak() { System.out.println("Meow"); } }

class AnimalFactory {
    public static Animal create(String type) {
        return switch (type.toLowerCase()) {
            case "dog" -> new Dog();
            case "cat" -> new Cat();
            default -> throw new IllegalArgumentException("Unknown: " + type);
        };
    }
}

Animal a = AnimalFactory.create("dog");
a.speak();

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