CircleQueue.java

package com.sprint.datastructure;

public class CircleQueue<E> {

	private Object[] elementData;
	private int size = 0;
	//队头
	private int front = 0;

	//队尾
	private int rear = 0;


	public CircleQueue(int capacity) {
		elementData = new Object[capacity];
	}	

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

	public boolean isFull() {
		return size == elementData.length;
	}

	public int size() {
		return size;
	}

	public void enQueue(E data) {
		if (isFull()) {
			throw new RuntimeException("The queue is full");
		}
		elementData[rear++] = data;
		size++;
	}

	public E deQueue() {
		if (isEmpty()) {
			throw new RuntimeException("The queue is empty");
		}
		E data = (E)elementData[front];
		elementData[front] = null;
		front = (front + 1) % elementData.length;
		size--;
		return data;
	}
}