java线程学习6——线程同步之同步锁

import java.util.concurrent.locks.reentrantlock;

public class account

{

 /**

  * 同步锁

  */

 private final reentrantlock lock = new reentrantlock();

  * 账户号

 private string accountno;

  * 账户余额

 private double balance;

 public account()

 {

  super();

 }

 public account(string accountno, double balance)

  this.accountno = accountno;

  this.balance = balance;

 @override

 public int hashcode()

  return accountno.hashcode();

 public boolean equals(object obj)

  if (null != obj && obj.getclass() == account.class)

  {

   account target = (account) obj;

   return target.accountno.equals(accountno);

  }

  return false;

  * 同步方法，同步方法的监视器是this，同步方法可以将该类变为线程安全的类

  * 任何时候只有一个线程获得对account对象的锁定，然后进入draw方法进行取钱

 public void draw(double drawamount)

  lock.lock();

  try

   if (balance >= drawamount)

   {

    system.out.println(thread.currentthread().getname() + "取出钞票成功" + drawamount);

    balance -= drawamount;

    system.out.println("余额为" + balance);

   }

   else

    system.out.println("余额不足");

  finally

   // 用finally块保证释放锁

   lock.unlock();

 /* 只提供getters，不提供setters，确保安全*/

 public string getaccountno()

  return accountno;

 public double getbalance()

  return balance;

}

public class drawthread extends thread

  * 模拟账户

 private account ac;

  * 当前取钱线程希望取得的钱数

 private double drawamount;

 public drawthread(string name, account ac, double drawamount)

  super(name);

  this.ac = ac;

  this.drawamount = drawamount;

 public void run()

  ac.draw(drawamount);

public class test

 public static void main(string[] args)

  account ac = new account("00000001", 1000);

  thread t1 = new thread(new drawthread("lily", ac, 800));

  thread t2 = new thread(new drawthread("tom", ac, 800));

  t1.start();

  t2.start();