问题：为什么仅能一个对象售卖-线程-电影票练习（同步锁）

 

package com.heima.dainyingpaio;

public class sale extends Thread{
    static int picket = 0;
   // static Object o = new Object();
    @Override
    public void run() {

        while (true) {
            synchronized(sale.class) {//同步代码块-锁
                if (picket < 100) {
                    try {
                        Thread.sleep(100);
                    } catch (InterruptedException e) {
                        throw new RuntimeException(e);
                    }
                    picket++;
                    System.out.println(getName() + "卖出第" + picket + "张票");
                } else {
                    break;
                }
            }
        }
    }
}

-------------------------------------------

Lock手动上锁

public class sale3 implements Runnable{
    //锁-手动锁lock，使用前需创建ReentrantLock对象
    int ticket = 0;
     Lock lock = new ReentrantLock();
    @Override
    public void run() {
        while (true) {
            lock.lock();
            try {
                if(ticket == 100){
                    break;
                }else{
                    Thread.sleep(10);
                    ticket++;
                    System.out.println(Thread.currentThread().getName() + "正在卖第" + ticket + "张票");
                }
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            } finally {
                lock.unlock();
            }
        }
    }
}

死锁：两个synronized重复嵌套