老师,麻烦看一下

package com.practice1;

/**
 * @author 谭昌
 * @date 2021/4/18
 */
public class Bank {
//账户
    private String account;
    //余额
    private double balance;

    public String getAccount() {
return account;
    }

public void setAccount(String account) {
this.account = account;
    }

public double getBalance() {
return balance;
    }

public void setBalance(double balance) {
this.balance = balance;
    }

@Override
    public String toString() {
return "Bank{" +
"account='" + account + '\'' +
", balance=" + balance +
'}';
    }

public Bank(String account, double balance) {
this.account = account;
        this.balance = balance;
    }
//存款
    public synchronized void SaveAccount(){
//获取当前余额
        double balance = getBalance();

        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
//修改余额
        balance+=100;
        setBalance(balance);
        System.out.println("存款之后的金额:"+balance);

    }
//取款
    public void TakeAccount() {
synchronized (this) {
//获取余额
            double balance = getBalance();

            //修改余额
            balance-=200;
            setBalance(balance);
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("取款之后的余额:" + balance);
        }
    }
}

package com.practice1;

import java.util.Scanner;

/**
 * @author 谭昌
 * @date 2021/4/18
 */
public class SaveAccount implements Runnable{
private Bank bank;

    @Override
    public void run() {
/* Scanner sc = new Scanner(System.in);
        System.out.print("请放入您的钞票:");
        double saveMoney = sc.nextDouble();*/
        bank.SaveAccount();

    }

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



}

package com.practice1;

import java.util.Scanner;

/**
 * @author 谭昌
 * @date 2021/4/18
 */
public class TakeAccount implements Runnable{
private Bank bank;

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

@Override
    public void run() {
/*  Scanner sc = new Scanner(System.in);
        System.out.print("您要取走的钞票:");
        double TakeMoney = sc.nextDouble();*/
        bank.TakeAccount();


    }
}

package com.practice1;

/**
 * @author 谭昌
 * @date 2021/4/18
 */
public class BankTest {
public static void main(String[] args) {
        Bank bank = new Bank("农业银行", 1000);
        SaveAccount sa = new SaveAccount(bank);
        TakeAccount ta = new TakeAccount(bank);
        Thread t1 = new Thread(sa, "t1");
        Thread t2 = new Thread(ta,"t2");
        t1.start();
        t2.start();
        try {
            t1.join();
            t2.join();
        } catch (InterruptedException e) {

            e.printStackTrace();
        }
        System.out.println(bank);
    }
}

在Bank类中,为什么我用修改余额用setBalance(balance-200),setBalance(banlance+100),和老师的结果不一样了