abstract-factory

Abstract factory

Intent

provide an interface for creating families of related or dependent objects without specifying their concrete classes

Applicability

Use the Abstract Factory pattern when

• a system should be independent of how its products are created, composed and represented.
• a system should be configured with one of multiple families of products
• a family of related product objects is designed to be used together, and you need to enforce this constraint
• you want to provide a class library of products, and you want to reveal yous their interface, not their implementation

Participants

• AbstractFactory
• ConcreteFactory
• AbstractProduct
• ConcreteProduct
• Client

Consequences

• It isolates concrete classes
• It makes exchanging product families easy
• It promotes consistency among products
• Supporting new kinds of products is difficult

classDiagram

class AbastractFactoy{
    createProductA()
    createProductB()
}
class ConcreteFactory1{
    createProductA()
    createProductB()
}
class ConcreteFactory2{
    createProductA()
    createProductB()
}
AbastractFactoy -- ConcreteFactory1
AbastractFactoy -- ConcreteFactory2
Client --|> AbastractFactoy
Client --|> AbstractProductA
Client --|> AbstractProductB
AbstractProductA -- ProductA2
AbstractProductA -- ProductA1
AbstractProductB -- ProductB2
AbstractProductB -- ProductB1
ProductA2 .. ConcreteFactory2
ProductB2 .. ConcreteFactory2
ProductA1 .. ConcreteFactory1
ProductB1 .. ConcreteFactory1

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Java implementation preview of MazeGame.java

public static void main(String[] args) {
        Maze simpleMaze = buildMaze(new MazeFactory());
        Maze mazeWithBomb = buildMaze(new BombedMazeFactory());
        Maze enchantedMaze = buildMaze(new EnchantedMazeFactory());
}

public static Maze buildMaze(Factory mazeFactory){
        Maze maze = mazeFactory.createMaze();

        Room r1 = mazeFactory.createRoom(1);
        Room r2 = mazeFactory.createRoom(2);

        Door theDoor = mazeFactory.createDoor(r1, r2);
        maze.addRoom(r1);
        maze.addRoom(r2);

        r1.setSide(North, mazeFactory.createWall());
        r1.setSide(East, theDoor);
        r1.setSide(North, mazeFactory.createWall());
        r1.setSide(North, mazeFactory.createWall());

        r2.setSide(North, mazeFactory.createWall());
        r2.setSide(East, theDoor);
        r2.setSide(North, mazeFactory.createWall());
        r2.setSide(North, mazeFactory.createWall());
        return maze;
}