线程问题（银行账户两个人同时操作一个账户）

public class Bank {

/**
* 银行类
*/
private static double balance=1000.00;

/**
* 取款
* @param money 要取款的金额
*/
public synchronized static void withDraw(double money){


if(money<=balance){
try {
Thread.currentThread().sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

balance-=money;
System.out.println("取款成功，卡上余额："+balance);
}else {
System.out.println("卡上余额不足，请从新输入！");
}
}


}

/**
* @author user
*测试银行类
*/
public class BankTest extends Thread {



@Override
public void run() {
Bank.withDraw(800);
}

public static void main(String[] args) {

BankTest bt1 = new BankTest();//卡
bt1.start();

BankTest bt2 = new BankTest();//存折
bt2.start();

}

}