用java实现循环队列

在Java中，你可以使用数组来实现循环队列。下面是一个简单的示例代码：

public class CircularQueue {
    private int[] queue;
    private int front;
    private int rear;
    private int size;
    
    public CircularQueue(int capacity) {
        queue = new int[capacity];
        front = -1;
        rear = -1;
        size = 0;
    }
    
    public boolean isEmpty() {
        return size == 0;
    }
    
    public boolean isFull() {
        return size == queue.length;
    }
    
    public void enqueue(int item) {
        if (isFull()) {
            System.out.println("Queue is full. Cannot enqueue more items.");
            return;
        }
        
        if (isEmpty()) {
            front = 0;
        }
        
        rear = (rear + 1) % queue.length;
        queue[rear] = item;
        size++;
        
        System.out.println("Enqueued: " + item);
    }
    
    public int dequeue() {
        if (isEmpty()) {
            System.out.println("Queue is empty. Cannot dequeue any items.");
            return -1;
        }
        
        int item = queue[front];
        queue[front] = 0;
        
        if (front == rear) {
            front = -1;
            rear = -1;
        } else {
            front = (front + 1) % queue.length;
        }
        
        size--;
        
        System.out.println("Dequeued: " + item);
        return item;
    }
    
    public void display() {
        if (isEmpty()) {
            System.out.println("Queue is empty.");
            return;
        }
        
        System.out.print("Queue: ");
        
        for (int i = 0; i < size; i++) {
            int index = (front + i) % queue.length;
            System.out.print(queue[index] + " ");
        }
        
        System.out.println();
    }
    
    public static void main(String[] args) {
        CircularQueue queue = new CircularQueue(5);
        
        queue.enqueue(1);
        queue.enqueue(2);
        queue.enqueue(3);
        queue.enqueue(4);
        queue.enqueue(5);
        
        queue.display();
        
        queue.dequeue();
        queue.dequeue();
        
        queue.display();
    }
}

这是一个基本的循环队列实现，它包含了常用的操作方法，如入队（enqueue）、出队（dequeue）、判空（isEmpty）、判满（isFull）和显示队列元素（display）。你可以根据需要进行扩展和修改。注意，在入队和出队操作时，使用取模运算（%）来实现循环的效果。