<> Subject + registerObserver(Observer observer): void + removeObserver(Observer observer): void + notifyObservers(): void

Baby - observers: ArrayList - cry: Cry + Baby() + registerObserver(Observer observer): void + removeObserver(Observer observer): void + notifyObservers(): void + angryCry(): void + hungryCry(): void + wetCry(): void

<> Observer + update(Cry cry): void

Mon

-baby: Subject

+Mom(Subject baby)

+update(Cry cry): void

Dad

-baby: Subject

+update(Cry cry): void

public class CribDriver { public void playBabySim() { Baby baby = new Baby(); Dad dad = new Dad(baby); Mom mom = new Mom(); baby.hungryCry(); baby.wetCry(); baby.hungryCry(); baby.hungryCry(); baby.wetCry(); } public static void main(String[] args) { CribDriver cd = new CribDriver(); cd.playBabySim(); }

}

Output

A new baby is born

This baby is hungry Dad feeds baby Mom cuddles and feeds baby

This baby is wet Dad calls mom Mom changes baby

This baby is angry! Dad puts in earplugs

This baby is hungry Mom cuddles and feeds baby

This baby is wet Mom changes baby