java第十次作业
《Java技术》第十次作业
(一)学习总结
1.用思维导图对java多线程的学习内容进行总结。
参考资料: XMind。
2.下面是一个单线程实现的龟兔赛跑游戏。
public class TortoiseHareRace {
public static void main(String[] args) {
int totalStep = 10;
int tortoiseStep = 0;
int hareStep = 0;
boolean[] flags = {true,false};
System.out.println("龟兔赛跑开始了...");
while(tortoiseStep < totalStep && hareStep < totalStep){
tortoiseStep++;
System.out.println("乌龟跑了"+tortoiseStep+"步...");
boolean isHareSleep = flags[((int)(Math.random()*10))%2];
if(isHareSleep){
System.out.println("兔子睡着了zzzz");
}else{
hareStep += 2;
System.out.println("兔子跑了"+hareStep+"步...");
}
}
}
}
阅读程序,采用实现Runnable接口的方式用多线程实现这个小游戏。下面给出主线程类,补充Tortoise线程类和Hare线程类。
public class TortoiseHareRace {
public static void main(String[] args) {
Tortoise tortoise = new Tortoise(10);
Hare hare = new Hare(10);
Thread tortoiseThread = new Thread(tortoise);
Thread hareThread = new Thread(hare);
tortoiseThread.start();
hareThread.start();
}
}
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补充完的程序为:
public class TortoiseHareRace { public static void main(String[] args) { Tortoise tortoise = new Tortoise(10); Hare hare = new Hare(10); Thread tortoiseThread = new Thread(tortoise); Thread hareThread = new Thread(hare); tortoiseThread.start(); hareThread.start(); } } class Tortoise implements Runnable { private int step; private int tortoiseStep = 0; public Tortoise(int step) { // TODO Auto-generated constructor stub this.step = step; } @Override public void run() { // TODO Auto-generated method stub pao(); } public void pao() { try { Thread.sleep(300); } catch (InterruptedException e) { e.printStackTrace(); } while (tortoiseStep < step) { tortoiseStep++; System.out.println("乌龟跑了" + tortoiseStep + "步..."); } } } class Hare implements Runnable { private int step; private int hareStep = 0; public Hare(int step) { // TODO Auto-generated constructor stub this.step = step; } @Override public void run() { // TODO Auto-generated method stub pao(); } public void pao() { try { Thread.sleep(300); } catch (InterruptedException e) { e.printStackTrace(); } boolean[] flags = { true, false }; while (hareStep < step) { boolean isHareSleep = flags[((int) (Math.random() * 10)) % 2]; if (isHareSleep) { System.out.println("兔子睡着了zzzz"); } else { hareStep += 2; System.out.println("兔子跑了" + hareStep + "步..."); } } } }
3.下面的程序是模拟了生产者——消费者问题,生产者生产10个数,消费者依次消费10个数,运行程序,看结果是否正常?存在什么问题?说明原因。使用synchronized, wait,notify解决程序出现的问题。写出修改的部分程序即可。
- 运行结果为:
-
询问同学后,修改为:
class Consumer implements Runnable { private Clerk clerk; public Consumer(Clerk clerk) { this.clerk = clerk; } public void run() { System.out.println("消费者开始消耗整数......"); // 消耗10个整数 for (int i = 1; i <= 10; i++) { try { // 等待随机时间 Thread.sleep((int) (Math.random() * 3000)); } catch (InterruptedException e) { e.printStackTrace(); } } } } class Producer implements Runnable { private Clerk clerk; public Producer(Clerk clerk) { this.clerk = clerk; } public void run() { System.out.println("生产者开始生产整数......"); // 生产1到10的整数 for (int product = 1; product <= 10; product++) { try { Thread.sleep((int) Math.random() * 3000); } catch (InterruptedException e) { e.printStackTrace(); } clerk.setProduct(product); // 将产品交给店员 } } } class Clerk { private int product = -1; // -1 表示目前没有产品 private int p; // 这个方法由生产者呼叫 public synchronized void setProduct(int product) { if (this.product != -1) { try { super.wait(); } catch (InterruptedException e) { e.printStackTrace(); } } this.product = product; p = this.product; System.out.printf("生产者设定 (%d)%n", this.product); getProduct(); this.product = -1; super.notify(); } // 这个方法由消费者呼叫 public synchronized int getProduct() { if (this.product == -1) { try { super.wait(); } catch (InterruptedException e) { e.printStackTrace(); } } System.out.printf("消费者取走 (%d)%n", p); this.product = -1; super.notify(); return this.product; } } public class ProductTest { public static void main(String[] args) { Clerk clerk = new Clerk(); Thread consumerThread = new Thread(new Consumer(clerk)); Thread producerThread = new Thread(new Producer(clerk)); consumerThread.start(); producerThread.start(); } }
(二)实验总结
1.模拟三个老师同时分发80分作业,每个老师相当于一个线程。
- 程序设计思路:定义一个Homework类,实现80份作业分发,定义一个Test类,创建老师对象,启动三个线程。
- 类图:
2.模拟一个银行存款的程序。假设有两个储户都去银行往同一个账户进行存款,一次存100,每人存三次。要求储户每存一次钱,账户余额增加100,并在控制台输出当前账户的余额。
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程序设计思路:创建Yinhang类,实现存入之后余额的变化;创建Chuhu类,实现向账户存款3次。每一个储户是一个线程;创建Test类,创建客户对象,启动线程。
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类图:
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实验问题分析:
问题1:运行结果不变,没有存款递增
解决方案:a.cunkuan(); System.out.println(Thread.currentThread().getName() + "存入100元" + "\t"+ a.toString());
(三)[代码托管]https://git.oschina.net/hebau_cs15/hebau-cs01cyl.git
- 码云commit历史截图