【DataStructure】Description and usage of queue

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【Description】

A queue is a collection that implements the first-in-first-out protocal. This means that the only accessiable object in the collection in the first one that was inserted. The most common example of a queue is a waiting line.

【Interface】

In the java Collections Framework includes a queue interface, which is implemented by four classes: the linkedList class, the AbstractQueue class, the priorityQUeue class, and the ArrayDeque class. For simple FIFO queues, the arrayDeque class the best choice:

Queue<String> queue = new ArrayDeque<String>();

【Demo】

package com.albertshao.ds.queue;//  Data Structures with Java, Second Edition//  by John R. Hubbard//  Copyright 2007 by McGraw-Hillimport java.util.*;public class TestStringQueue {  public static void main(String[] args) {    Queue<String> queue = new ArrayDeque<String>();    queue.add("GB");    queue.add("DE");    queue.add("FR");    queue.add("ES");    System.out.println(queue);    System.out.println("queue.element(): " + queue.element());    System.out.println("queue.remove(): " + queue.remove());    System.out.println(queue);    System.out.println("queue.remove(): " + queue.remove());    System.out.println(queue);    System.out.println("queue.add(\"IE\"): ");    queue.add("IE");    System.out.println(queue);    System.out.println("queue.remove(): " + queue.remove());    System.out.println(queue);  }}

【Result】

[GB, DE, FR, ES]queue.element(): GBqueue.remove(): GB[DE, FR, ES]queue.remove(): DE[FR, ES]queue.add("IE"): [FR, ES, IE]queue.remove(): FR[ES, IE]

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