编程实现生产者-消费者问题。提示：生产者-消费者问题是一个实现线程同步的问题，生产者线程总是先运行，消费者线程在其后，两者交替运行，在程序中生产者线程和消费者线程可以共享数据，生产者线程为数据赋值，消费者线程将数据返回。可以利用创建Thread类的子类来实现。-Programming producer- consumer issues. Tip: Producer- Consumer problem is an implementation of thread synchronization problems, the producer thread is always the first, the consumer thread in the following two alternately operating in the program producer and consumer threads can share data, the producer thread for data assignment, consumer thread will return the data. Can be used to create a subclass of Thread to achieve.