模拟一个队列(java)
简介
队列是一种特殊的线性表，它只允许在表的前端（front）进行删除操作，而在表的后端（rear）进行插入操作。进行插入操作的端称为队尾，进行删除操作的端称为队头。队列中没有元素时，称为空队列。
在队列这种数据结构中，最先插入的元素将是最先被删除的元素；反之最后插入的元素将最后被删除的元素，因此队列又称为“先进先出”（FIFO—first in first out）的线性表。
队列空的条件： front=rear
队列满的条件： rear = MAXSIZE
/** * simulate queue struct by java * * @author Bruce * @date Sep 8, 2011 * @version 1.0 */public class Queue {private int maxSize;private long[] queueArray;private int front;// the head of queueprivate int rear;// the end of queueprivate int nItems;/** * Constructor a queue,the size is s;now the queue is null, and the front is * zero and the rear is negative one * * @param s */public Queue(int s) {maxSize = s;queueArray = new long[maxSize];front = 0;rear = 0;nItems = 0;}public void insert(long j) {// if the the inserted items great the size of queue,// the rear return the initial value and the next item will// override the corresponding valueif (rear == maxSize)rear = 0;queueArray[rear++] = j;nItems++;// the count of the items}/** * remove the item from the 'front' position,every time the front will be * added one */public long remove() {long temp = queueArray[front++];// if the front equals the size of queue,the front will return the// initial valueif (front == maxSize)front = 0;nItems--;if (nItems < 0)nItems = 0;return temp;}public long peekFront() {return queueArray[front];}public boolean isEmpty() {return (nItems == 0);}public boolean isFull() {return (nItems == maxSize);}public int size() {return nItems;}public static void main(String[] args) {Queue queue = new Queue(3);queue.insert(3);queue.insert(6);queue.insert(8);// queue.insert(4);System.out.println("size:" + queue.size());System.out.println(queue.peekFront());queue.remove();System.out.println(queue.peekFront());queue.remove();System.out.println(queue.peekFront());queue.remove();// System.out.println(queue.peekFront());// queue.remove();System.out.println("size:" + queue.size());}}