BrewingMethod.java

public interface BrewingMethod {
    public String brew();
}

CoffeeShop.java

public class CoffeeShop {
    public String brewCoffee() {
        Siphone siphone = new Siphone();
        return siphone.brew() + "が出来上がりました [_]P";
    }
}

CoffeeShopApp.java

public class CoffeeShopApp {
    public static void main(String... args) {
        CoffeeShop coffeeShop = new CoffeeShopApp();
        coffeeShop.brewCoffee();
    }
}

Drip.java

public class Drip implements BrewingMethod {
    @Override
    public String brew() {
        return "ドリップ式コーヒー";
    }
}

Siphon.java

public class Siphon implements BrewingMethod {
    @Override
    public String brew() {
        return "サイフォンでいれたコーヒー";
    }
}