数据结构之循环队列

package MyQueue;
/**
 * 
 * @author zz384dian
 * @time 2018-2-22
 * @content 循环队列实现
 */
public class MyQueue<E>{
	private Object objs[];
	private int front;
	private int back;
	private int size;
	
	public MyQueue(){
		size = 0;
		objs = new Object[10];
		front = 0;
		back = 0;
	}
	
	public E add(Object o){
		//扩容
		if(size == objs.length){
			Object temp[] = objs;
			objs = new Object[10+temp.length];
			int index = 0;
			for(int i=front;i<temp.length;i++)
				objs[index++] = temp[i];//从对头到数组的最大容量遍历存入新数组
			for(int i=0;i<back;i++)
				objs[index++] = temp[i];//再从位置0到队尾遍历存入新数组
			back = size;
			front = 0;
		}
		objs[size++] = o;
		if(back == objs.length){
			back = 0;//队尾循环到头需重新循环
		}else{
			back++;//否则加一
		}
		
		return (E)o;
	}
	
	public E peek(){
		if(empty()){
			return null;
		}else{
			return (E)objs[front];
		}
	}
	
	public E poll(){
		E e;
		if(empty()){
			return null;
		}else{
			e = (E)objs[front];
			front++;//头出来后，向前移位
			if(front == objs.length){
				front = 0;//移位后如果正好等于队列大小，就置0，重新循环
			}
		}
		size--;
		return e;
	}
	
	public int size(){
		return size;
	}
	
	public boolean empty(){
		return size == 0?true:false;
	}
}

p.s.关于add方法中扩容的图解