• Creational design pattern
• For applications that need to switch out entire families of objects (rather than a single product)
  • Framework phrased in terms of interfaces and abstract classes
  • Concrete subclasses of the framework decide what to instantiate

Problem illustration: Application, Window, Button, and other elements are a framework for implementing user interfaces.

What kind of specific Window and Button should application use?

• Create a matrix of product types and platforms
• Create abstract product interfaces and concrete product classes
• Create the abstract factory class with create methods for abstract products
• Implement concrete factories for each platform
• Replace direct constructor calls with factory calls

public abstract class AbstractFactory {
  public abstract Room createRoom();
  public abstract Door createDoor();
}
public abstract class Room {}
public abstract class Door {}

// Concrete creator and product: dungeon game
public class DungeonFactory extends AbstractFactory {
  @Override public Room createRoom() {
    return new Chamber();
  }
  @Override public Door createDoor() {
    return new WoodenDoor();
  }
}
public class Chamber extends Room {}
public class WoodenDoor extends Door {}

// Concrete creator and product: enchanted maze game
public class EnchantedMazeFactory extends AbstractFactory {
  @Override public Room createRoom() {
    return new EnchantedRoom();
  }
  @Override public Door createDoor() {
    return new EnchantedDoor();
  }
}
public class EnchantedRoom extends Room {}
public class EnchantedDoor extends Door {}

Before: Clients directly instantiate classes