import java.util.ArrayList;
import java.util.List;
import java.util.Random;

//Producer-Consumer problem
public class ProducerConsumerMain {

    public static final int N_CONSUMER = 10;
    public static final int N_PRODUCER = 20;

    public static void main(String[] args) {
        Puffer puffer = new Puffer(10);
        for (int i = 0; i< N_CONSUMER; i++) {
            Thread t = new Thread(new Consumer(puffer));
            t.start();
        }
        for (int i = 0; i< N_PRODUCER; i++) {
            Thread t = new Thread(new Producer(puffer));
            t.start();
        }
    }
}

//Storage/Warehouse
class Puffer {
    private int maxSize;
    List<Integer> list = new ArrayList<Integer>();

    public Puffer(int maxSize) {
        super();
        this.maxSize = maxSize;
    }

    //Put a "product" (number) in the storage
    public synchronized void deposit(int product) {
        System.out.println("+ deposit");
        while(list.size() == maxSize) {
            try {
                //the storage is full, waiting for free space
                System.out.println("wait in deposit");
                wait();
                System.out.println("wait ended in deposit");
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        list.add(product);
        System.out.println("deposit " + list.size());
        //notify others to check the conditions again
        notifyAll();
    }

    //Get a "product" (number) from the storage
    public synchronized int extract() {
        System.out.println("- extract");
        while(list.isEmpty()) {
            try {
                //the storage is empty, waiting for a product
                System.out.println("wait in extract");
                wait();
                System.out.println("wait ended in extract");
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        int product = list.remove(list.size()-1);
        System.out.println("extract " + list.size());
        //notify others to check the conditions again
        notifyAll();
        return product;
    }

}

class Producer implements Runnable {

    private Puffer puffer;
    private Random random = new Random();

    public Producer(Puffer puffer) {
        super();
        this.puffer = puffer;
    }

    @Override
    public void run() {
        //Put a "product" (number) in the storage
        puffer.deposit(random.nextInt());
    }

}

class Consumer implements Runnable {

    private Puffer puffer;

    public Consumer(Puffer puffer) {
        super();
        this.puffer = puffer;
    }

    @Override
    public void run() {
        //Get a "product" (number) from the storage
        puffer.extract();
    }

}