savelock.java

《Java2程序设计实用教程(第2版)》课件

//【例7.5】  互斥的存取款线程设计。

public class SaveLock extends Thread             //带互斥锁的存款线程类
{
    private Account account;                     //账户   
    private double value;                        //存款金额
    
    public SaveLock(Account a1,double value)
    {
        this.account = a1;
        this.value = value;
    }
    
    public void run()
    {
        synchronized(this.account)               //声明临界区，锁定账户对象
        {
            double howmatch = this.account.balance();
            try
            {
                 sleep(1);                       //花费时间
            }
            catch(InterruptedException e)  {}
            if (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 FetchLock extends Thread                   //带互斥锁的取款线程类
{
    private Account account;
    private double value;
    
    public FetchLock(Account a1,double value)
    {
        this.account = a1;
        this.value = value;
    }
    
    public void run()
    {
        synchronized(this.account)               //声明临界区，锁定账户对象
        {
            double howmatch = this.account.balance();
            try
            {
                sleep(1);                        //花费时间
            }
            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 SaveLock(wang,100)).start();
        (new SaveLock(wang,200)).start();
        (new FetchLock(wang,300)).start();
    }

}

/*
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

*/