account.java

这是一个银行帐户的存取钱线程Java程序

//【例7.4】  银行账户的存取款线程设计。

public class Account                             //账户类
{
    private String name;                         //储户姓名
    private double balance;                      //账户余额
    
    public Account(String name)
    {
        this.name = name;
        this.balance = 0;
    }
    
    public String getName()                      //返回账户名
    {
        return name;
    }

    public double balance()                      //查看账户余额
    {
        return balance;                      
    }

    public void put(double value)                //存款操作，参数为存入金额
    {
        if (value>0)
            this.balance += value;               //存款操作使余额值增加
    }
    
    public double get(double value)              //取款操作，参数为取款金额，返回实际取到金额
    {
        if (value>0)
        {
           if (value<=this.balance)
               this.balance -= value;            //取款操作使余额值减少
           else                                  //账户余额不够所取时
           {
               value = this.balance;             //取走全部余额
               this.balance = 0;
           }
           return value;                         //返回实际取款额
        }
        return 0;
    }
}

class Save extends Thread                        //存款线程类
{
    private Account account;                     //账户   
    private double value;                        //存款金额
    
    public Save(Account a1,double value)
    {
        this.account = a1;
        this.value = value;
    }
    
    public void run()
    {
        double howmatch = this.account.balance();//查看账户余额
        
        try
        {
            sleep(1);                            //花费时间，线程执行被打断
        }
        catch(InterruptedException e)  {}
        
        this.account.put(this.value);
        System.out.println(this.account.getName()+"账户：现有"+howmatch+
                ", 存入"+this.value+", 余额"+this.account.balance());
    }
}


class Fetch extends Thread                       //取款线程类
{
    private Account account;                     //账户   
    private double value;                        //取款金额
    
    public Fetch(Account a1,double value)
    {
        this.account = a1;
        this.value = value;
    }
    
    public void run()
    {
        double howmatch = this.account.balance();//查看账户余额
        
        try
        {
            sleep(1);                            //花费时间，线程执行被打断
        }
        catch(InterruptedException e) {}
        
        System.out.println(this.account.getName()+"账户：现有"+howmatch+
            ", 取走"+this.account.get(this.value)+", 余额"+this.account.balance());
    }

    public static void main(String args[])
    {
        Account wang = new Account("Wang");
        (new Save(wang,100)).start();
        (new Save(wang,200)).start();
        (new Fetch(wang,300)).start();

        (new Save(new Account("Li"),100)).start();
    }

}

/*
实际取走300元。程序运行结果如下：        
Wang账户：现有0.0, 存入100.0, 余额100.0
Wang账户：现有0.0, 存入200.0, 余额300.0                    //有错，三者数据不符
Wang账户：现有0.0, 取走300.0, 余额0.0                      //有错，三者数据不符
Li账户：现有0.0, 存入100.0, 余额100.0

没有sleep语句时，程序设计运行结果与线程调度有关。可能为

Wang账户：现有0.0, 存入100.0, 余额100.0
Wang账户：现有100.0, 取走100.0, 余额0.0
Wang账户：现有0.0, 存入200.0, 余额200.0

Wang账户：现有0.0, 存入100.0, 余额100.0
Wang账户：现有100.0, 存入200.0, 余额300.0
Wang账户：现有300.0, 取走300.0, 余额0.0


扩充功能：
明细表
    static int count;
    static final double overdraft=0.0;                 //透支
    
自动分配账户号？

consume//消费    

remainder

    public int get(int i) throws EmptyException                        //欲取金额i,返回实际取到金额
    {
        if (i>0 && i<=balance)
        {
            value -= i;                //取款，value值减少
            return i;                  //返回取款额
        }
        else                           //账户余额不够所取时
        {
            throw EmptyException("余额不满，取款操作未完成!");   //抛出异常
            return 0;
        }
    }
*/