Creational_Abstract Factory

✅ Abstract Factory

• similar to factory,
• but with a focus on the client

• add client to factory pattern

• interface creates the related classes instance
• 👍🏻 can hide which concrete product to the client

✅ Diagram

👀 ShipFactory example

Factory 🆚 AbstractFactory

• 공통점: make creation of instance abstract with instance
• Factory: hide the creation of instance in concrete factory
• focus more on how to implement factory, interitance
• move instance creation process to concrte factory class
• 👉🏻 defines an interface for creating an object, but lets subclasses (or a factory class) decide which class to instantiate

• 🆚 create one product

• AbstractFactory: client does not have to see the concrete factory
• focus more on how to use factory, composition
• create related instances without relying on a concrete class
• 👉🏻 interface for creating families of related objects without specifying their concrete classes.
• 🆚 multiple related products

🆚 Factory
CarFactory → Mercedes or Kia

🆚 Abstract Factory
GUIFactory
   ├─ createButton()
   └─ createCheckbox()

WindowsFactory → WindowsButton + WindowsCheckbox
MacFactory → MacButton + MacCheckbox

👀

✔️ Abstract product Interface

interface Button {
    //method that button can perform
    press();
}

interface Checkbox {
    tick();
}

✔️ Concete products

class WindowsButton implements Button {
    //override method
    press();
}

class MacButton implements Button {
    //override method
    press();
}

class WindowsCheckbox implements Checkbox {
    //override method
    tick();
}

class MacCheckbox implements Checkbox {
    //override method
    tick();
}

✔️ Abstract Factory interface

interface GUIFactory {
    Button createButton();
    Checkbox createCheckbox();
}

✔️ Concete Factory

class WindowsFactory implements GUIFactory {

    public Button createButton() {
        return new WindowsButton();
    }

    public Checkbox createCheckbox() {
        return new WindowsCheckbox();
    }
}

class MacFactory implements GUIFactory {

    public Button createButton() {
        return new MacButton();
    }

    public Checkbox createCheckbox() {
        return new MacCheckbox();
    }
}

✔️ Client

Button windowButton = new WindowsFactory().createButton();
Checkbox windowCheckbox = new WindowsFactory().createCheckbox();

🛠️

• in javax.xml.parsers
• DocumentBuilderFatory to create xml

public static void main(String[[ args) throws ParserConfigurationException, IOException, SAXException{
  DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
  DocumentBuilder builder = factory.newDocumentBuilder();
  Document document = builder.parse(new File("src/main/resource/config.xml"));
  System.out.println(document.getDocumentElement());
}

• FactoryBean<T>