队列的实现(Java)

 

class Queue
{
    private int front;
    private int rear;
    private int[] a;
    
    public Queue(int size)
    {
        this.front = this.rear = 0;
        this.a = new int[size];
    }
    
    public boolean isFull()
    {
        return (this.rear + 1) % this.a.length == this.front;
    }
    
    public boolean isEmpty()
    {
        return this.rear == this.front;
    }
    
    public void EnQueue(int k) throws Exception
    {
        if(this.isFull())
            throw new Exception("Overflow.");
        else
        {
            this.a[this.rear] = k;
            this.rear = (this.rear + 1) % this.a.length;
        }
    }
    
    public int DeQueue() throws Exception
    {
        if(this.isEmpty())
            throw new Exception("Underflow.");
        else
        {
            int key = this.a[front];
            this.front = (this.front + 1) % this.a.length;
            return key;
        }
    }

    public int getLength()
    {
        return (this.rear - this.front + this.a.length) % this.a.length;
    }
}