CareerCup_3.7 - PetShelter

Pet.java

package Chapter3;

import java.util.Date;

public abstract class Pet {
    private Date arrivedTime;
    protected String name;
    
    public Pet() {
	arrivedTime = new Date();
    }
    
    public abstract PetKind kind();
    
    public Date getArriveTime() {
	return arrivedTime;
    };
    
    public String getName() {
	return name;
    };
}

public class Dog extends Pet {
    public Dog(String n) {
	name = n;
    }
    
    @Override
    public PetKind kind() {
	return PetKind.Dog;
    }
}

public class Cat extends Pet {
    public Cat(String n) {
	name = n;
    }
    
    @Override
    public PetKind kind() {
	return PetKind.Cat;
    }
}

public enum PetKind {
    Cat,
    Dog
}

Shelter.java

package Chapter3;

import java.util.LinkedList;
import java.util.Queue;

public class Shelter {
    private Queue<Dog> dogQueue = new LinkedList<Dog>();
    private Queue<Cat> catQueue = new LinkedList<Cat>();

    public void enqueue(Pet p) {
	switch (p.kind()) {
	case Dog:
	    dogQueue.add((Dog) p);
	    break;
	case Cat:
	    catQueue.add((Cat) p);
	    break;
	default:
	    break;
	}
    }

    public Cat dequeueCat() {
	return catQueue.isEmpty() ? null : catQueue.remove();
    }

    public Dog dequeueDog() {
	return dogQueue.isEmpty() ? null : dogQueue.remove();
    }

    public Pet dequeueAny() {
	if (catQueue.isEmpty())
	    return dogQueue.isEmpty() ? null : dogQueue.remove();
	if (dogQueue.isEmpty())
	    return catQueue.isEmpty() ? null : catQueue.remove();
	return dogQueue.peek().getArriveTime()
		.compareTo(catQueue.peek().getArriveTime()) < 0 ? 
			dogQueue .remove() : catQueue.remove();
    }
    
    public static void main(String[] args) throws InterruptedException {
	Shelter shelter = new Shelter();
	shelter.enqueue(new Cat("Tom"));
	Thread.sleep(100);
	shelter.enqueue(new Dog("Goofy"));
	Thread.sleep(100);
	shelter.enqueue(new Dog("Hazard"));
	Thread.sleep(100);
	shelter.enqueue(new Cat("Garfield"));
	
	shelter.print();
	
	System.out.println("dequeue any = " + shelter.dequeueAny().getName());
	System.out.println("dequeue dog = " + shelter.dequeueDog().getName());
	System.out.println("dequeue cat = " + shelter.dequeueCat().getName());
    }

    private void print() {
	System.out.print("Cat: ");
	for (Cat c : catQueue)
	    System.out.print(c.getName() + ", ");
	System.out.println();
	
	System.out.print("Dog: ");
	for (Dog d : dogQueue)
	    System.out.print(d.getName() + ", ");
	System.out.println();
    }
}