CircleQueue.java

package datastructure.queue;

/**
 * 用数组实现循环队列
 * @author liuxin
 *
 * @param <E>
 */
public class CircleQueue <E> {
	
	private final static int DEFAULT_SIZE = 10;
	
	//用数组来保存循环队列的元素
	private Object[] elementData = new Object[DEFAULT_SIZE] ;
	
	//队头
	private int front = 0;  
	//队尾  
	private int rear = 0;
	
	private int size = 0;
	
	public boolean isEmpty() {
		return size == 0;
        
    }

    public int size() {
        return size;
    }

    

    public void enQueue(E data) {
        if (size >= DEFAULT_SIZE) {
            throw new RuntimeException("队列已满");
        }
        elementData[rear] = data;
        rear = (rear + 1) % DEFAULT_SIZE;
        size++;
    }

    @SuppressWarnings("unchecked")
    public E deQueue() {
        if (size <= 0) {
            throw new RuntimeException("队列已空");
        }
        size--;
        Object object = elementData[front];
        front = (front + 1) % DEFAULT_SIZE;
        return (E) object;
    }
}