新手请问一个多线程中同步的有关问题

新手请教一个多线程中同步的问题

Java code

class Demo implements Runnable{    private int ticket = 10 ;    public synchronized void fun()    {            if (this.ticket >0)            {                            try                {                    Thread.sleep(100);                }                catch (Exception e)                {                }                System.out.println(Thread.currentThread().getName()+"-->卖票:"+this.ticket--);            }        }    public void run()    {        while(ticket>0)        {            this.fun();        }    }}public class ThreadDemo07{    public static void main(String[] args)    {        Demo d = new Demo();        Thread t1 = new Thread(d,"A");        Thread t2 = new Thread(d,"B");        Thread t3 = new Thread(d,"C");        t1.start();        t2.start();        t3.start();    }}