关于线程的问题

package 线程同步;

public class FetchMoney
{
public static void main(String[] args)
{
Bank bank = new Bank();//模拟一个账户
MoneyThread money1 = new MoneyThread(bank);//取款机取款
MoneyThread money2 = new MoneyThread(bank);//银行取款
money1.start();
money2.start();
}
}

class Bank
{
private int money = 1000;

// private static int money=100;

public int getMoney(int number)
{
if (number < 0)
{
return -1;
}
else if (number > money)
{
return -2;
}
else if (money < 0)
{
return -3;
}
else
{
try
{
Thread.sleep(1000);
}
catch (InterruptedException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
money -= number;
System.out.println("LEFT:" + money);
return number;
}
}
}

class MoneyThread extends Thread
{
private Bank bank;

public MoneyThread(Bank bank)
{
this.bank = bank;
}

@Override
public void run()
{
System.out.println(bank.getMoney(800));

}
}




最近在看张龙老师的视频的线程这块
因为这个运行结果有很多种,
运行出来的下面这2种结果百思不得其解
怎么可能最后剩下的钱为200,
怎么想都是-600

控制台第1种打印结果:
LEFT:200
LEFT:200
800
800

控制台第2种打印结果:
LEFT:200
800
LEFT:200
800


求大能解释

线程交叉~

。。。。。