public class ProductTest {

    public static void main(String[] args)   
    {  
        Clerk clerk = new Clerk();  
        Thread producerThread = new Thread(new Producer(clerk));  
        Thread consumerThread = new Thread(new Consumer(clerk));  

        producerThread.start();  
        consumerThread.start();  
    }  
    static
 
 class Clerk {
        private static final int MAX_PRODUCT = 20;
        private static final int MIN_PRODUCT = 0;

        private int PRODUCT = 0;

        public synchronized void addProduct() {
            if (this.PRODUCT >= MAX_PRODUCT) {
                try {
                    wait();
                    System.out.println("產品已滿,請稍候再生產"
 
);
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                return;
            }
            this.PRODUCT++;
            System.out.println("生產者生產了第"+this.PRODUCT+"個產品");
            notifyAll();
        }

        public
 
 synchronized void getProduct() {
            if(this.PRODUCT <= MIN_PRODUCT) {
                try {
                    wait();
                    System.out.println("產品處於缺貨狀態");
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                return;
            }
            System.out.println("消費者消費了第" + this.PRODUCT + "個產品");  
            this.PRODUCT--;
            notifyAll();
        }
    }

    static class Producer implements Runnable{
        private Clerk clerk;
        public Producer(Clerk clerk)
        {
            this.clerk=clerk;
        }
        @Override
        public void run() {
            // TODO Auto-generated method stub
            System.out.println("生產者開始生產產品");
            while(true)
            {
                try {
                  Thread.sleep(1000);
                } catch (Exception e) {
                    // TODO: handle exception
                }
                clerk.addProduct();
            }

        }

    }

    static class Consumer implements Runnable{
        private Clerk clerk;
        public Consumer(Clerk clerk)
        {
            this.clerk=clerk;
        }
        @Override
        public void run() {
            // TODO Auto-generated method stub
            System.out.println("消費者開始消費產品");
            while(true)
            {
                try {
                  Thread.sleep(1000);
                } catch (Exception e) {
                    // TODO: handle exception
                }
                clerk.getProduct();
            }

        }

    }
}