java之多线程抢火车票

一、创建线程的方法是实现runnable，重写run方法，执行线程需要丢入runnable接口实现类,调用start方法

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//多个线程同时操作一个类
    //火车票
public class TestTread4 implements Runnable{

    //票数
   private int ticketNums = 10;
    @Override
    public void run() {

        while (true) {
            if (ticketNums <= 0) {
                break;
            }
            try {
                Thread.sleep(200);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName()+"--->拿到了第"+ticketNums-- +"张票");
        }

    }

    public static void main(String[] args) {
        TestTread4 testTread4 = new TestTread4();

        new Thread(testTread4, "小明").start();
        new Thread(testTread4,"老师").start();
        new Thread(testTread4,"黄牛").start();
    }
}

发现问题:多个线程操作同一个资源的情况下,线程不安全，数据紊乱.

加上锁就搞定

public class TestTread4 implements Runnable{

    //票数
   private int ticketNums = 10;
    @Override
    public synchronized void run() {

        while (true) {
            if (ticketNums <= 0) {
                break;
            }
            try {
                Thread.sleep(200);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName()+"--->拿到了第"+ticketNums-- +"张票");
        }

    }

    public static void main(String[] args) {
        TestTread4 testTread4 = new TestTread4();

        new Thread(testTread4, "小明").start();
        new Thread(testTread4,"老师").start();
        new Thread(testTread4,"黄牛").start();
    }
}

当有200人抢100张票

public class TicketRunnable implements Runnable {

    /**
     * 总票数
     */
    private final int ticketSize = 100;

    /**
     * 抢票人数
     */
    private final int peopleSize = 200;

    /**
     * 票数
     */
    private int ticketNum;

    /**
     * 人数
     */
    private int peopleNum;

    @Override
    public void run() {
        while(ticketNum < ticketSize && peopleNum < peopleSize){
            synchronized (this){
                if(ticketNum < ticketSize && peopleNum < peopleSize){
                    if((int)(Math.random() * 20) % 2 == 1){
                        System.out.println(Thread.currentThread().getName() + "第" + (++peopleNum) + "个人抢到第" + (++ticketNum) + " 张票");
                    try {
                        Thread.sleep(100);
                    }catch (Exception e){
                        e.printStackTrace();
                    }
                    }else {
                        System.out.println(Thread.currentThread().getName() + "第" + (++peopleNum) + " 个人未抢到票");
                    }
                }
            }
        }

    }
}

public class TestTicket {
    public static void main(String[] args) {
        TicketRunnable tr = new TicketRunnable();
        Thread t1 = new Thread(tr , "窗口A");
        Thread t2 = new Thread(tr , "窗口B");
        Thread t3 = new Thread(tr , "窗口C");
        Thread t4 = new Thread(tr , "窗口D");
        t1.start();
        t2.start();
        t3.start();
        t4.start();
    }
}