2.1使用synchronized实现同步方法

1.创建Account类，该类用于模拟银行账户

public class Account {

    //账户的余额
    private double balance;

    //取得账户的余额
    public double getBalance() {
        return balance;
    }

    //设置账户的余额
    public void setBalance(double balance) {
        this.balance = balance;
    }

    //将增加的数量加入到余额中
    public synchronized void addAmount(double amount) {

            double tmp=balance;
            try {
                Thread.sleep(10);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            tmp+=amount;
            balance=tmp;

            System.out.println("存入后，当前账户余额:"+balance);


    }

    //从余额中减去相应的数量
    public synchronized void subtractAmount(double amount) {

            double tmp=balance;
            try {
                Thread.sleep(10);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            if(tmp>=amount)
            {
                tmp-=amount;
                balance=tmp;
                System.out.println("取出后，当前账户余额:"+balance);
            }



    }

}

2.创建实现Runnable接口的Bank类，模拟ATM机取款

public class Bank implements Runnable{

   private Account account;


    public Bank(Account account) {
        this.account=account;
    }

    @Override
    public void run() {
        //每次 从账户余额中减去1000
        for (int i=0; i<10; i++){
            account.subtractAmount(1000);
        }
    }

}

3.创建实现Runnable接口的Company类，用于模拟往账户中汇款

public class Company implements Runnable{

  private Account account;


    public Company(Account account) {
        this.account=account;
    }

    @Override
    public void run()
    {
        for (int i=0; i<10; i++){
            account.addAmount(1000);
        }
    }

}

4.主类的实现

public class Main {


    public static void main(String[] args) {
        // 创建爱你 一个新的账户
        Account account=new Account();
        // 设置账户的初始余额
        account.setBalance(1000);

        // 创建一个模拟的公司实体对象，并作为线程的参数传入启动线程
        Company company=new Company(account);
        Thread companyThread=new Thread(company);
        // 创建一个模拟的银行实体对象，并作为线程的参数传入启动线程
        Bank bank=new Bank(account);
        Thread bankThread=new Thread(bank);

        // 打印账户的余额
        System.out.printf("Account : Initial Balance: %f\n",account.getBalance());

        // 启动线程
        companyThread.start();
        bankThread.start();

        try {
            // 等待线程运行完毕
            companyThread.join();
            bankThread.join();
            // 打印最终的余额
            System.out.printf("Account : Final Balance: %f\n",account.getBalance());
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

}

4.运行结果如下:

在模拟存取账户金额的同时，这边也考虑到了实际的情况：如果账户余额不够需要取出的钱的话，那么久不能取。