queuebyobject.htm
来自「“常见程式演算”主要收集一些常见的程式练习题目」· HTM 代码 · 共 171 行
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<title>伫列 - 使用Java 作物件封装</title>
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<h3><a href="http://caterpillar.onlyfun.net/GossipCN/index.html">From
Gossip@caterpillar</a></h3>
<h1><a href="AlgorithmGossip.htm">Algorithm Gossip: 伫列 - 使用Java 作物件封装</a></h1>
<h2>说明</h2>
如果您使用C++或Java等支援物件导向的语言来实作伫列，您可以使用类别的方式来包括伫列的功能，将所有的伫列操作由堆叠物件来处理，一旦包装完成，则使用伫列物件的时候，只要呼叫加入、删除等方法，而无需处理伫列的front、rear或判断是否为空等细节。<br>
<h2>解法</h2>
使用C++与使用Java来作类别包装其实是类似的，在这边我们使用Java实作，因为它的语法看来较简洁；Java虽然没有指标，但可以使用参考（Reference）来达到链结的效果，一个节点的类别包装方式如下：<br>
<div style="margin-left: 40px;"><span style="font-weight: bold; font-family: Courier New,Courier,monospace;">class Node { </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> private int data; // 节点资料 </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> private Node next; // 下一个节点位置 </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> public void setData(int data); // 节点资料 </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> public void setNext(Node next); // 下一个节点位置 </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> public int getData(); // 传回节点资料 </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> public Node getNext(); // 传回下一个节点位置 </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;">}</span><br>
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<br>
其中next是个物件参考名称，它可以用来参考至（指向）下一个节点物件的记忆体位置，而伫列类别可以如下包装：<br>
<div style="margin-left: 40px;"><span style="font-weight: bold; font-family: Courier New,Courier,monospace;">class Queue { </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> private Node front; </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> private Node rear; </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> private String name; // 只是个名称 </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> // 利用建构子建立伫列 </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> public Queue(); </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> public Queue(String name); </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> // 插入资料至前端 </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> public void add(int data); </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> // 显示前端资料 </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> public void printFront(); </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> // 删除前端资料 </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> public void del(); </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> // 列出伫列内容 </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;"> public void list(); </span><br style="font-weight: bold; font-family: Courier New,Courier,monospace;">
<span style="font-weight: bold; font-family: Courier New,Courier,monospace;">}</span><br>
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利用物件导向来包装资料结构，虽然在设计时需要花较多的心思，但设计完成之后，日后呼叫使用就简单了，以后您只要注意主程式的逻辑设计就可以了。 <br>
<br>
<h2> 实作</h2>
<ul>
<li> Java </li>
</ul>
<pre>import java.io.*; <br><br>// 节点 <br>class Node { <br> private int data; // 节点资料 <br> private Node next; // 下一个节点位置 <br><br> public void setData(int data) { <br> this.data = data; <br> } <br><br> public void setNext(Node next) { <br> this.next = next; <br> } <br><br> public int getData() { <br> return data; <br> } <br><br> public Node getNext() { <br> return next; <br> } <br>} <br><br>// 伫列 <br>class Queue { <br> private Node front; <br> private Node rear; <br> private String name; // 只是个名称 <br><br> public Queue() { <br> this("list"); <br> } <br><br> // 利用建构子建立伫列 <br> public Queue(String name) { <br> this.name = name; <br> front = new Node(); <br> front.setNext(null); <br> rear = front; <br> } <br><br> // 插入资料至顶端 <br> public void add(int data) { <br> Node newNode = new Node(); <br><br> if(front.getNext() == null) <br> front.setNext(newNode); <br><br> newNode.setData(data); <br> newNode.setNext(null); <br> rear.setNext(newNode); <br> rear = newNode; <br> } <br><br> // 显示前端资料 <br> public void printFront() { <br> if(front.getNext() == null) <br> System.out.print("\n伫列为空！"); <br> else <br> System.out.print("\n顶端值：" + <br> front.getNext().getData()); <br> } <br><br> // 删除前端资料 <br> public void del() { <br> Node tmpNode; <br> <br> if(front.getNext() == null) { <br> System.out.print("\n伫列已空！"); <br> return; <br> } <br><br> tmpNode = front.getNext(); <br> front.setNext(tmpNode.getNext()); <br> tmpNode = null; <br> } <br><br> // 列出伫列内容 <br> public void list() { <br> Node tmpNode; <br><br> tmpNode = front.getNext(); <br><br> System.out.print("\n伫列内容："); <br> while(tmpNode != null) { <br> System.out.print(tmpNode.getData() + " "); <br> tmpNode = tmpNode.getNext(); <br> } <br> } <br>} <br><br>public class Queueshow { <br> public static void main(String[] args) <br> throws IOException { <br> int input, select; <br> BufferedReader buf; <br> buf = new BufferedReader(<br> new InputStreamReader(System.in)); <br><br> Queue q1 = new Queue("伫列测试"); <br><br> while(true) { <br> System.out.print("\n\n请输入选项(-1结束)："); <br> System.out.print("\n(1)插入值至伫列"); <br> System.out.print("\n(2)显示伫列前端"); <br> System.out.print("\n(3)删除前端值"); <br> System.out.print("\n(4)显示所有内容"); <br> System.out.print("\n$c>"); <br><br> select = Integer.parseInt(buf.readLine()); <br><br> if(select == -1) <br> break; <br><br> switch(select) { <br> case 1: <br> System.out.print("\n输入值："); <br> input = Integer.parseInt(buf.readLine()); <br> q1.add(input); <br> break; <br> case 2: <br> q1.printFront(); <br> break; <br> case 3: <br> q1.del(); <br> break; <br> case 4: <br> q1.list(); <br> break; <br> default: <br> System.out.print("\n选项错误！"); <br> } <br> } <br><br> System.out.println(""); <br> } <br>}<br>
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