多线程之线程同步

package Demo1;

/**
 * 经典线程同步问题---银行取钱问题
 * Created by Petty on 2017/4/10.
 */


/**
 * Account类
 */
class Account{
    //封装账户编号、账户余额两个成员变量
    private String acccountNo;
    private double balance;

    public Account(){}

    public Account(String accountNo,double balance){
        this.acccountNo=accountNo;
        this.balance=balance;
    }
    public void setAcccountNo(String acccountNo){
        this.acccountNo = acccountNo;
    }
    public String getAcccountNo(){
        return this.acccountNo;
    }
    public void setBalance(double balance){
        this.balance=balance;
    }
    public double getBalance(){
        return this.balance;
    }

}
public class Thread_2 extends Thread{
    //声明用户账户
    private Account account;
    //当前取钱线程希望取的金额
    private double drawAmount;

    public Thread_2(String name,Account account,double drawAmount){
        super(name);
        this.account=account;
        this.drawAmount=drawAmount;
    }

    public void run() {
        //使用account作为同步监视器，任何线程进入下面代码块之前，
        // 必须先对account账户锁定---其他程无法获得锁，也无法修改它
        synchronized (account) {
            //账户金额大于取钱金额
            if (account.getBalance() >= drawAmount) {
                System.out.println(getName() + "取钱成功！吐出钞票" + drawAmount);
                try {
                    Thread.sleep(1);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                //修改金额
                account.setBalance(account.getBalance() - drawAmount);
                System.out.println("账户编号："+account.getAcccountNo()+ "的余额为" + account.getBalance());
            } else {
                System.out.println(getName() + "取钱失败！余额不足！");
            }
        }
    }
    public static void main(String[] args){
            //创建一个账户
            Account account=new Account("123456789",1000);
            //创建两个线程模拟对同一个账户取钱
            Thread_2 td1=new Thread_2("张三",account,800);
            td1.start();
            Thread_2 td2=new Thread_2("李四",account,800);
            td2.start();
    }
}
运行结果：

张三取钱成功！吐出钞票800.0
账户编号：123456789的余额为200.0
李四取钱失败！余额不足！