猫狗队列

Posted 2020-07-30 澄海乌鸦

要求：

1.用户可以将cat类和dog类的实例放入队列

2.用户可以按照放入的顺序取出队列中的全部实例

 

思路：

设计一个类PetEnterQueue ，用于记录放入队列的每个元素的时间戳，取出时按时间戳来判断从dog队列或cat队列取出元素

 

具体代码如下：

public class Pet {
    private String type ;
    
    public Pet(String type) {
        this.type = type ;
    }
    
    public String getPetType() {
        return this.type ;
    }
}


public class Dog extends Pet{
    public Dog() {
        super("dog") ;
    }
}

public class Cat extends Pet{
    public Cat() {
        super("cat") ;
    }
}

public class PetEnterQueue {
    private Pet pet ;
    private long count ;
    
    public PetEnterQueue(Pet pet, long count) {
        this.pet = pet ;
        this.count = count ;
    }
    
    public Pet getPet() {
        return this.pet ;
    }
    
    public long getCount() {
        return this.count ;
    }
    
    public String getEnterPetType() {
        return this.pet.getPetType() ;
    }
}


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

public class DogCatQueue {
    private Queue<PetEnterQueue> dogQ ;
    private Queue<PetEnterQueue> catQ ;
    public long count ;
    
    public DogCatQueue() {
        this.dogQ = new LinkedList<PetEnterQueue>() ;
        this.catQ = new LinkedList<PetEnterQueue>() ;
        this.count = 0 ;
    }
    
    public void add(Pet pet) {
        if(pet.getPetType().equals("dog")) {
            this.dogQ.add(new PetEnterQueue(pet, this.count++)) ;
        } else if(pet.getPetType().equals("cat")) {
            this.catQ.add(new PetEnterQueue(pet, this.count++)) ;
        }
        else throw new RuntimeException("err, not dog or cat") ;
    }
    
    public Pet pollAll() {
        if(!this.dogQ.isEmpty() && !this.catQ.isEmpty()) {
            if(this.dogQ.peek().getCount() < this.catQ.peek().getCount()) {
                return this.dogQ.poll().getPet() ;
            }
            else return this.catQ.poll().getPet() ;
        }
        else if(!this.dogQ.isEmpty()) {
            return this.pollDog();
        }
        else if(!this.catQ.isEmpty()) {
            return this.pollCat() ;
        }
        else {
            throw new RuntimeException("err, quque is empty") ;
        }
    }
    
    public Dog pollDog() {
        if(!this.isDogQueueEmpty()) {
            return (Dog) this.dogQ.poll().getPet() ;
        }
        else throw new RuntimeException("Dog queue is empty") ;
    }
    
    public Cat pollCat() {
        if(!this.isCatQueueEmpty()) {
            return (Cat) this.catQ.poll().getPet() ;
        }
        else throw new RuntimeException("Cat queue is empty") ;
    }
    
    public boolean isEmpty() {
        return this.dogQ.isEmpty()&&this.catQ.isEmpty() ;
    }
    
    public boolean isDogQueueEmpty() {
        return this.dogQ.isEmpty() ;
    }
    
    public boolean isCatQueueEmpty() {
        return this.catQ.isEmpty() ;
    }
}