线程--生产者，消费者

生产一个，消费一个；也可以用wait notify模式

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

public class  ThreadDemo{
    public static void main(String[] args) {
        ShareData shareData=new ShareData();
        new Thread(() -> {
            for (int j = 0; j <5 ; j++) {
                try {
                    shareData.increment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"AAA").start();

        new Thread(() -> {
            for (int j = 0; j <5 ; j++) {
                try {
                    shareData.decrement();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        },"BBB").start();
    }
}

class ShareData {
    int num = 0;
    private Lock lock = new ReentrantLock();
    Condition condition = lock.newCondition();

    void increment() throws InterruptedException {
        lock.lock();
        while (num != 0) {
            condition.await();
        }
        num++;
        System.out.println(num);
        condition.signalAll();
        lock.unlock();
    }

    void decrement() throws InterruptedException {
        lock.lock();
        while (num == 0) {
            condition.await();
        }
        num --;
        System.out.println(num);
        condition.signalAll();
        lock.unlock();
    }
}