Java实现队列(循环队列，链队列)

Posted 2021-12-12 Wecccccccc

循环队列:

package SeqQueue;

public class Queue {
    private int data[];
    private int queueSize;
    private int front,rear;

    public Queue()
    {
        data = new int[100];
        queueSize = 100;
        front = rear = 0;
    }

    public Queue(int n)
    {
        queueSize = n;
        data = new int[queueSize];
        front = rear = 0;
    }

    public boolean isFull()
    {
        if ((rear+1)%queueSize==front) return true;
        return false;
    }

    public boolean isEmpty()
    {
        if (front==rear) return true;
        return false;
    }

    public int lenQueue()
    {
        return (rear-front+queueSize)%queueSize;
    }


    public boolean enQueue(int e)
    {
        if (isFull()) return false;
        data[rear] = e;
        rear = (rear+1)%queueSize;
        return true;
    }

    public boolean deQueue()
    {
        if (isEmpty()) return false;
        front = (front+1)%queueSize;
        return false;
    }

    public int frontQueue()
    {
        if (isEmpty())
        {
            System.out.println("The queue is empty");
            return 0;
        }

        return data[front];
    }
}

测试类:

package SeqQueue;

public class TestQueue {
    public static void main(String[] args)
    {
        Queue q = new Queue();
        q.enQueue(25);
        q.enQueue(56);
        q.enQueue(123);
        q.enQueue(8);
        System.out.println(q.frontQueue());
        q.deQueue();
        System.out.println(q.frontQueue());
        System.out.println(q.lenQueue());
        q.deQueue();
        q.deQueue();
        q.deQueue();

    }
}

链队列:

package LinkQueue;

public class Queue {
    private class queueNode
    {
        private int data;
        private queueNode next;

        public queueNode(int e)
        {
            data = e;
            next = null;
        }

        public queueNode()
        {
            data = 0;
            next = null;
        }
    }

    private queueNode front,rear;

    public Queue()
    {
         rear = new queueNode();
        rear.next = null;
        front = rear;
    }

    public boolean isEmpty()
    {
        return front==rear;
    }

   public boolean enQueue(int e)
   {
       queueNode s = new queueNode(e);
       rear.next = s;
       rear = s;
       return true;
   }

   public boolean deQueue()
   {
       if (isEmpty()) return false;
       queueNode p = front.next;
       front.next = p.next;
       if (p==rear) rear = front;
       p.next = null;
       return true;

   }

   public int frontQueue()
   {
       if (isEmpty())
       {
           System.out.println("The queue is empty");
           return 0;
       }
       return front.next.data;
   }

    public int lenQueue()
    {
        int j = 0;
        queueNode p = front.next;
        while(p!=null)
        {
            j++;
            p = p.next;
        }
        return j;
    }



}

测试类:

package LinkQueue;

import LinkQueue.Queue;

public class TestQueue {
    public static void main(String[] args)
    {
        Queue q = new Queue();
        q.enQueue(25);
        q.enQueue(56);
        q.enQueue(123);
        q.enQueue(8);
        System.out.println(q.frontQueue());
        q.deQueue();
        System.out.println(q.frontQueue());
        System.out.println(q.lenQueue());
        q.deQueue();
        q.deQueue();
        q.deQueue();

    }
}