文章目录

• 题目
• 难点
• 源代码

题目

编写一个Java程序,该程序将启动4个线程,其中3个是掷硬币线程,1个是主线程。每个掷硬币线程将连续掷出若干次硬币(10次以内,次数随机生成);主线程将打印出正面出现的总次数以及正面出现的概率。

难点

因为要计算数量以及出现概率，所以必须将所有子线程内的数据同步到主线程内。

源代码

Coin.java

package com.web.homework03;


public class Coin{

    public static void main(String[] args) throws InterruptedException {
        test test = com.web.homework03.test.getTest();
        Thread[] trr = new Thread[3];
        for (int i = 0; i < 3; i++) {
            trr[i] = new Thread(new Roll(test), "线程" + (i + 1));
        }
        for (Thread thread : trr) {
            thread.start();
        }
        for (Thread thread : trr) {
            thread.join();
        }
        System.out.println("正面总次数为："+test.getRoll());
        System.out.println("正面总次数为："+test.getRandoms());
        System.out.println("出现正面的概率为："+(double)test.getRoll()/test.getRandoms());
    }
}

Roll.java

package com.web.homework03;

public class Roll implements Runnable{
    private test test01;
    public Roll(test test){
        this.test01 = test;
    }
    @Override
    public void run() {
        test01.method();
    }
}

test.java

package com.web.homework03;

import java.util.Random;

public class test {
    private int randoms;
    private int roll;

    public int getRandoms() {
        return randoms;
    }

    public void setRandoms(int randoms) {
        this.randoms = randoms;
    }

    public int getRoll() {
        return roll;
    }

    public void setRoll(int roll) {
        this.roll = roll;
    }

    private test() {
    }
    private static final test test = new test();
    public static test getTest() {
        return test;
    }
    public synchronized void method() {
        Random random = new Random();
        int times = random.nextInt(10);
        randoms += times;
        for (int i =0;i<times;i++){
            if (random.nextBoolean()){
                roll++;
            }
        }
    }
}