Java基于双向链表实现双端队列结构（算法源码）

/* * 基于双向链表实现双端队列结构 */ package dsa; public class Deque_DLNode implements Deque { protected DLNode header;//指向头节点（哨兵） protected DLNode trailer;//指向尾节点（哨兵） protected int size;//队列中元素的数目 //构造函数 public Deque_DLNode() { header = new DLNode(); trailer = new DLNode(); header.setNext(trailer); trailer.setPrev(header); size = 0; } //返回队列中元素数目 public int getSize() { return size; } //判断队列是否为空 public boolean isEmpty() { return (0 == size) ? true : false; } //取首元素（但不删除） public Object first() throws ExceptionQueueEmpty { if (isEmpty()) throw new ExceptionQueueEmpty("意外：双端队列为空"); return header.getNext().getElem(); } //取末元素（但不删除） public Object last() throws ExceptionQueueEmpty { if (isEmpty()) throw new ExceptionQueueEmpty("意外：双端队列为空"); return trailer.getPrev().getElem(); } //在队列前端插入新节点 public void insertFirst(Object obj) { DLNode second = header.getNext(); DLNode first = new DLNode(obj, header, second); second.setPrev(first); header.setNext(first); size++; } //在队列后端插入新节点 public void insertLast(Object obj) { DLNode second = trailer.getPrev(); DLNode first = new DLNode(obj, second, trailer); second.setNext(first); trailer.setPrev(first); size++; } //删除首节点 public Object removeFirst() throws ExceptionQueueEmpty { if (isEmpty()) throw new ExceptionQueueEmpty("意外：双端队列为空"); DLNode first = header.getNext(); DLNode second = first.getNext(); Object obj = first.getElem(); header.setNext(second); second.setPrev(header); size--; return(obj); } //删除末节点 public Object removeLast() throws ExceptionQueueEmpty { if (isEmpty()) throw new ExceptionQueueEmpty("意外：双端队列为空"); DLNode first = trailer.getPrev(); DLNode second = first.getPrev(); Object obj = first.getElem(); trailer.setPrev(second); second.setNext(trailer); size--; return(obj); } //遍历 public void Traversal() { DLNode p = header.getNext(); while (p != trailer) { System.out.print(p.getElem()+" "); p = p.getNex