Deque示例

Deque是一个更精简的元素集合，支持两端元素的插入和删除。 它发音为’双端队列’。 Deque接口提供了插入，删除和检查队列两端元素的方法。 这些方法是：

• addFirst()，offerFirst()和push() – 将元素插入双端队列的头部。
• add()，addLast()，offerLast()和offer() – 将元素插入双端队列的尾部。
• element()，getFirst()，peek()和peekFirst() – 从双端队列的头部检索元素。
• getLast()和peekLast() – 从双端队列的尾部检索元素。
• remove()，removeFirst()，poll()，pollFirst()和pop() – 从双端队列中删除元素。
• removeLast()和pollLast() – 从双端队列的尾部删除元素。

ArrayDeque和LinkedList是Collection API中Deque接口的实现。

文件：DequeExample.java –

package com.yiibai.tutorial;  import java.util.Deque; import java.util.LinkedList;  /**  * @author yiibai  *  */ public class DequeExample {     public static void main(String[] args) {         Deque<String> deque=new LinkedList<>();         /*Adding element to deque*/         deque.add("One");         deque.addFirst("Two");         deque.addLast("Three");         deque.offer("Four");         deque.offerFirst("Five");         deque.offerLast("Six");         deque.push("Seven");           System.out.println("Elements in deque: "+deque);         System.out.println();          /*Retrieving elements from deque*/         System.out.println("element() : "+deque.element());         System.out.println("getFirst() : "+deque.getFirst());         System.out.println("getLast() : "+deque.getLast());         System.out.println("peek() : "+deque.peek());         System.out.println("peekFirst() : "+deque.peekFirst());         System.out.println("peekLast() : "+deque.peekLast());          /*Removing elements from deque */         System.out.println();          System.out.println("remove() : "+deque.remove());         System.out.println("Elements in deque after removal : "+deque);          System.out.println("removeFirst() : "+deque.removeFirst());         System.out.println("Elements in deque after removal : "+deque);          System.out.println("removeLast() : "+deque.removeLast());         System.out.println("Elements in deque after removal : "+deque);          System.out.println("poll() : "+deque.poll());         System.out.println("Elements in deque after removal : "+deque);          System.out.println("pollFirst() : "+deque.pollFirst());         System.out.println("Elements in deque after removal : "+deque);          System.out.println("pollLast() : "+deque.pollLast());         System.out.println("Elements in deque after removal : "+deque);          System.out.println("pop() : "+deque.pop());         System.out.println("Elements in deque after removal : "+deque);     } } 

执行上面示例代码，得到以下结果：

Elements in deque: [Seven Five Two One Three Four Six]  element() : Seven getFirst() : Seven getLast() : Six peek() : Seven peekFirst() : Seven peekLast() : Six  remove() : Seven Elements in deque after removal : [Five Two One Three Four Six] removeFirst() : Five Elements in deque after removal : [Two One Three Four Six] removeLast() : Six Elements in deque after removal : [Two One Three Four] poll() : Two Elements in deque after removal : [One Three Four] pollFirst() : One Elements in deque after removal : [Three Four] pollLast() : Four Elements in deque after removal : [Three] pop() : Three Elements in deque after removal : []