почему считывает не верно значения, если я использовала Lock?

public class Test {
    public static `введите сюда код`void main(String[] args) throws InterruptedException {
        Runner runner = new Runner();

         Thread thread1 = new Thread(new Runnable() {
             @Override
             public void run() {
                 runner.ferstThread();
             }
         });

         Thread thread2 = new Thread(new Runnable() {
             @Override
             public void run() {
                runner.secondThread();
             }
         });

         thread1.start();
         thread2.start();

         thread1.join();
         thread2.join();

         runner.finished();
    }
}

class Runner {
    private Account account1 = new Account();
   private Account account2 = new Account();

   private Lock lock1 = new ReentrantLock();
   private Lock lock2 = new ReentrantLock();
    public void ferstThread(){
        Random random = new Random();

        for (int i = 0; i < 10000;i++){
            lock1.lock();
            lock2.lock();
            try {
                Account.transfer(account1, account2, random.nextInt(100));
            }finally {
                lock1.unlock();
                lock2.unlock();
            }

        }

    }
    public void secondThread(){
        Random random = new Random();

        for (int i = 0; i < 10000;i++) {
            lock1.lock();
            lock2.lock();
            try {
                Account.transfer(account2, account1, random.nextInt(100));
            }finally {
                lock1.unlock();
                lock2.unlock();
            }

        }
    }

    public void finished(){
        System.out.println(account1.getBalance());
        System.out.println(account2.getBalance());
        System.out.println("Total balance " + (account1.getBalance() + account2.getBalance()));

    }
}

class Account{
    private int balance = 10000;

    public void deposit(int amout){
        balance += amout;
    }

    public void wihtdraw(int amout){
        balance += amout;
    }

    public int getBalance(){
        return balance;
    }

    public static void transfer(Account acc1,Account acc2,int amout){
        acc1.wihtdraw(amout);
        acc2.deposit(amout);

    }
}