Java 加显式加锁（lock）

通俗易懂的用例

import java.util.concurrent.locks.ReentrantLock;

public class BuyTicket {
    public static void main(String[] args) {
        Buy buy = new Buy();
        new Thread(buy,"老王").start();//三个线程操作一个ticketNum很危险
        new Thread(buy,"老李").start();
        new Thread(buy,"老张").start();
    }
}
class Buy implements Runnable{
    int ticketNum = 1000;
    boolean flag = true;
    private final ReentrantLock  lock = new ReentrantLock();//重入锁实现了lock接口
    @Override
    public void run() {
        while (flag){
            buy();
        }
    }
    void buy(){
        try {
            lock.lock();//加锁
            Thread.sleep(0);
            if (ticketNum<0) {
                flag = false;
                return;
            }
            else{
                System.out.println(Thread.currentThread().getName()+"买到,票还剩"+ticketNum--);
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        finally {
            lock.unlock();//解锁
        }

    }
}