abstract class AbstractProductA {
  abstract public void actionA();
}

public class ProductA1 extends AbstractProductA {
  public void actionA() {
    System.out.println("ProductA1");
  }
}

public class ProductA2 extends AbstractProductA {
  public void actionA() {
    System.out.println("ProductA2");
  }
}

abstract class AbstractProductB {
  abstract public void actionB();
}

public class ProductB1 extends AbstractProductB {
  public void actionB() {
    System.out.println("ProductB1");
  }
}

public class ProductB2 extends AbstractProductB {
  public void actionB() {
    System.out.println("ProductB2");
  }
}

abstract class AbstractFactory {
  abstract public AbstractProductA createProductA();
  abstract public AbstractProductB createProductB();
  static AbstractFactory getFactory() {
    String s = "1"; // ← 環境によって値が変わる変数
    if (s.equals("1")) {
      return new ConcreteFactory1();
    } else if (s.equals("2")){
      return new ConcreteFactory2();
    }
    return null;
  }
}

public class ConcreteFactory1 extends AbstractFactory {
  public AbstractProductA createProductA() {
    return new ProductA1();
  }
  public AbstractProductB createProductB() {
    return new ProductB1();
  }
}

public class ConcreteFactory2 extends AbstractFactory {
  public AbstractProductA createProductA() {
    return new ProductA2();
  }
  public AbstractProductB createProductB() {
    return new ProductB2();
  }
}

public class Client {
  public static void main(String[] args) {
    AbstractFactory factory = AbstractFactory.getFactory();
    AbstractProductA pA = factory.createProductA();
    AbstractProductB pB = factory.createProductB();

    pA.actionA();
    pB.actionB();
  }
}

C:\JavaHello\Abstract Factory>java Client
ProductA1
ProductB1

C:\JavaHello\Factory Method>