使用Condition可以实现线程按序交替

package org.meng.juc;

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

/**
 * @ClassName: ProducerAndConsumer
 * @Description: while 解决虚假唤醒问题 -> wait()方法需要在while循环中使用
 * @Author: MengMeng
 * @Date: 2021/1/17 1:40 下午
 * @Version: v1.0
 */
public class ProducerAndConsumer {

    public static void main(String[] args) {
        Clerk clerk = new Clerk();

        Productor productor = new Productor(clerk);
        Consumer consumer = new Consumer(clerk);

        new Thread(productor,"生产者 A").start();
        new Thread(consumer,"消费者 B").start();

        new Thread(productor,"生产者 C").start();
        new Thread(consumer,"消费者 D").start();

    }

    static class Clerk {
        private int product = 0;

        private Lock lock = new ReentrantLock();
        private Condition condition = lock.newCondition();

        public void get() {
            lock.lock();
            try {
                // while 解决虚假唤醒问题 -> wait()方法需要在while循环中使用
                while (product >= 10) {
                    System.out.println("产品已满");
                    try {
                        condition.await();
                    } catch (Exception e) {

                    }
                }
                System.out.println(Thread.currentThread().getName() + ":" + ++product);
                condition.signalAll();
            }finally {
                lock.unlock();
            }
        }

        public synchronized void sale() {
            lock.lock();
            try {
                while (product <= 0) {
                    System.out.println("缺货");
                    try {
                        condition.await();
                    } catch (Exception e) {

                    }
                }
                System.out.println(Thread.currentThread().getName() + ":" + --product);
                condition.signalAll();
            }finally {
                lock.unlock();
            }
        }
    }

    static class Productor implements Runnable {
        private Clerk clerk;

        public Productor(Clerk clerk) {
            this.clerk = clerk;
        }

        @Override
        public void run() {
            for (int i = 0; i < 20; i++) {
                clerk.get();
            }
        }
    }

    static class Consumer implements Runnable {
        private Clerk clerk;

        public Consumer(Clerk clerk) {
            this.clerk = clerk;
        }

        @Override
        public void run() {
            for (int i = 0; i < 20; i++) {
                clerk.sale();
            }
        }
    }

}