Java第十次作业--多线程
（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。
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。
补充后的程序为：
package workp;
class Tortoise implements Runnable {
private int tortoiseStep = 0;
private int totalStep = 10;
public Tortoise(int tortoiseStep) {
this.tortoiseStep = tortoiseStep;
}
public void run() {
while (tortoiseStep < totalStep) {
tortoiseStep++;
System.out.println("乌龟跑了" + tortoiseStep + "步");
}
}
}
class Hare implements Runnable {
private int step = 0;
private int totalStep = 10;
boolean[] flags = { true, false };
public Hare(int step) {
this.step = step;
}
public void run() {
while (step < this.totalStep) {
boolean isHareSleep = flags[((int) (Math.random() * 10)) % 2];
if (isHareSleep) {
System.out.println("兔子睡着了！");
} else {
this.step=this.step+2;
System.out.println("兔子跑了" + this.step + "步");
}
}
}
}
public class Test {
public static void main(String[] args) {
Tortoise tortoise = new Tortoise(0);
Hare hare = new Hare(0);
System.out.println("龟兔赛跑开始了...");
Thread tortoiseThread = new Thread(tortoise);
Thread hareThread = new Thread(hare);
tortoiseThread.start();
hareThread.start();
}
}
程序截图如下：
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。
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();
}
clerk.getProduct();// 从店员处取走整数
}
}
}
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
}
}
}
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();
}
}
class Clerk {
private int product = -1; // -1 表示目前没有产品
// 这个方法由生产者呼叫
public void setProduct(int product) {
this.product = product;
System.out.printf("生产者设定 (%d)%n", this.product);
}
// 这个方法由消费者呼叫
public int getProduct() {
int p = this.product;
System.out.printf("消费者取走 (%d)%n", this.product);
return p;
}
}
修改后的代码：
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();
try {
Thread.sleep(300);
} catch (InterruptedException e) {
e.printStackTrace();
}
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();
}
}
try {
Thread.sleep(300);
} 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 Test {
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
实验内容：
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。
程序代码：
package work;
class Page implements Runnable{
private int page=80;
public void run(){
for(int i=1;i<81;i++){
if(page>0){
System.out.println(Thread.currentThread().getName()+"正在分发第"+page--+"张试卷");
}else{
System.exit(1);
}
}
}
}
public class Work {
public static void main(String args[]){
Page p=new Page();
new Thread(p,"1").start();
new Thread(p,"2").start();
new Thread(p,"3").start();
}
}
程序截图：
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。
问题：最后存款金额不对
解决：没有对Bank类进行同步操作，导致金额不对。
部分代码如下：
package cunKuang;
public class SavePer implements Runnable {
private String name;
private Bank b=new Bank();
public SavePer(){
}
public SavePer(String name){
this.name=name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Bank getB() {
return b;
}
public void setB(Bank b) {
this.b = b;
}
public void run(){
synchronized(b){
for(int i=1;i<4;i++){
try {
Thread.sleep(300);
b.save();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName()+"第"+i+"次存款,"+name+"的余额为："+b.getYue());
}
}
}
}
程序运行截图如下：
（三）代码托管
