import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class SynchronizedThread {
    public void useThread() {
        Bank bank = new Bank();
        NewThread new_thread = new NewThread(bank);
        System.out.println("线程1");
        Thread thread1 = new Thread(new_thread);
        thread1.start();
        System.out.println("线程2");
        Thread thread2 = new Thread(new_thread);
        thread2.start();
    }

    public static void main(String[] args) {
        SynchronizedThread st = new SynchronizedThread();
        st.useThread();
    }
}

class Bank {
    private int account = 100;
    private Lock lock = new ReentrantLock();
    public int getAccount() {
        lock.lock();
        try{
            return account;
        }finally {
            lock.unlock();
        }
    }

    public void save(int money) {
        lock.lock();
        try {
            account += money;
        } finally {
            lock.unlock();
        }
    }
}

class NewThread implements Runnable {
    private Bank bank;

    public NewThread(Bank bank) {
        this.bank = bank;
    }

    @Override
    public void run() {
        for (int i = 0; i < 10; i++) {
            bank.save(10);
            System.out.println(i + "账户余额为：" +bank.getAccount());
        }
    }
}

========================下面是打印的结果==================
线程1
线程2
0账户余额为：120
0账户余额为：120

1账户余额为：140
2账户余额为：150
3账户余额为：160
4账户余额为：170
5账户余额为：180
6账户余额为：190
7账户余额为：200
8账户余额为：210
9账户余额为：220
1账户余额为：130
2账户余额为：230
3账户余额为：240
4账户余额为：250
5账户余额为：260
6账户余额为：270
7账户余额为：280
8账户余额为：290
9账户余额为：300

线程1和线程2的0账户重复了，请问这是怎么回事？