工場と匿名の内部クラス



 
	//   &  
	interface Service{
		void method1();
		void method2();
	}

	interface ServiceFactory{
		Service getService();
	}

	class Implementation1 implements Service{
		private Implementation1(){}
		public void method1(){
			System.out.println("Implementation1 methdo1");
		}
		public void method2(){
			System.out.println("Implementation1 methdo2");
		}
		public static ServiceFactory factory = new ServiceFactory(){
			public Service getService() {
				return new Implementation1();
			}
		};
	}

	class Implementation2 implements Service{
		private Implementation2(){};
		public void method1() {
			System.out.println("Implementation2 methdo1");
		}
		public void method2() {
			System.out.println("Implementation2 methdo2");
		}
		public static ServiceFactory factory = new ServiceFactory(){
			public Service getService(){
				return new Implementation2();
			}
		};
	}

	public class Factories {
		public static void serviceConsumer(ServiceFactory fact){
			Service s =fact.getService();
			s.method1();
			s.method2();
		}
		
		public static void main(String[] args){
			serviceConsumer(Implementation1.factory);
			serviceConsumer(Implementation2.factory);
		}
	}

 
このように、1つの工場が1つのサービスに対応します.具体例:
 
 
package InnerClass;

interface Game{
	boolean move();
}
interface GameFactory{
	Game getGame();
}
class Checkers implements Game{
	private Checkers(){}
	private int moves = 0;
	private static final int MOVES = 3;
	public boolean move(){
		System.out.println("Checkers move "+moves);
		return ++moves != MOVES;
	}
	public static GameFactory factory = new GameFactory(){
		public Game getGame(){
			return new Checkers();
		}
	};
}
class Chess implements Game{
	private Chess(){}
	private int moves = 0;
	private static final int MOVES = 4;
	public boolean move(){
		System.out.println("Chess move "+moves);
		return ++moves != MOVES;
	}
	public static GameFactory factory = new GameFactory(){
		public Game getGame(){
			return new Chess();
		}
	};
}
public class Games {
	public static void playGame(GameFactory factory){
		Game s = factory.getGame();
		while(s.move()){
		}
	}
	public static void main(String[] args){
		playGame(Checkers.factory);
		playGame(Chess.factory);
	}
}

 
 
 
PS:Thinking in Javaより抜粋