Java并发系列之JUC中的Lock锁与synchronized同步代码块问题

public class SaleTicketDemo01 {
    public static void main(String[] args) {
        Ticket ticket = new Ticket();
        new Thread(()->{
            for (int i = 0; i < 60; i++) {
                ticket.sale();
            }
        },"AA").start();
        },"BB").start();
        new Thread(() -> {
        }, "CC").start();
    }
    static class Ticket{
        // 50张飘票
        private int num = 50;
        // 售票 synchronized（同步代码块） 本质: 队列，锁
        public synchronized void sale(){
            if (num > 0){
                System.out.println(Thread.currentThread().getName()+"卖出了"+(num--)+"票,剩余："+num);
        }
}

public class SaleTicketDemo02 {

    public static void main(String[] args) {
        Ticket2 ticket = new Ticket2();
        new Thread(()->{ for (int i = 0; i < 60; i++) ticket.sale(); },"AA").start();
        new Thread(()->{ for (int i = 0; i < 60; i++) ticket.sale(); },"BB").start();
        new Thread(()->{ for (int i = 0; i < 60; i++) ticket.sale(); },"CC").start();
    }

    static class Ticket2{
        // 50张飘票
        private int num = 50;

        // 加锁三部曲
        // 1、 创建锁 => new ReentrantLock();
        // 2、 加锁 =>  lock.lock();
        // 3、 释放锁 => lock.unlock();
        public void sale(){
            // 可重入锁  默认：非公平锁：十分不公平，可以插队。（默认非公平锁）
            Lock lock = new ReentrantLock();
            // 加锁
            lock.lock();
            try {
                // 执行业务
                if (num > 0){
                    System.out.println(Thread.currentThread().getName()+"卖出了"+(num--)+"票,剩余："+num);
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                // 解锁
                lock.unlock();
            }
        }
    }
}