生产者和消费者
生产者 : 不停的生产商品
消费者 : 不停的消费商品
多线程

public class mainProgram {
    public static void main(String[] args) {
        // 生产者
        Producer p = new Producer();
        Thread t = new Thread(p);
        t.start();

        // 消费者
        Customer c = new Customer();
        Thread t2 = new Thread(c);
        t2.start();

    }
}

生产者

public class Producer implements Runnable {

    static int thing = 0;
    static final Object Object = new Object();

    @Override
    public void run() {
        while (thing < 200) {
            synchronized (Object) {
                thing += 2;
                try {
                    Thread.sleep(100);
                } catch (Exception e) {
                    e.printStackTrace();
                }
                System.out.println(Thread.currentThread().getName() + "--> 剩余: " + thing + "个");
            }
        }
    }
}

消费者

public class Customer implements Runnable{
    @Override
    public void run() {//Producer.thing != 0
        while (true) {
            synchronized (Producer.Object) {
                if(Producer.thing > 0){
                    Producer.thing --;
                    try {
                        Thread.sleep(100);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    System.out.println(Thread.currentThread().getName() + "--> 剩余: " + Producer.thing + "个");
                }
            }
        }
    }
}