import java.util.Random;

class Message {
    private String payload;
    private boolean empty = true;
 // syncronised read method used by consumer to read messages
    public synchronized String read() {
        while(empty) {
        }
        empty = true;
        return payload;
    }

    public synchronized void write(String payload) {
        while(!empty) {
        }
        this.payload = payload;
        empty = false;
    }
}

// Writer class or Producer class writes four messages
class Writer implements Runnable {
    private Message message;

    public Writer(Message message) {
        this.message = message;
    }

    public void run() {
        String payload[] = {
                "Humpty Dumpty sat on a wall",
                "Humpty Dumpty had a great fall",
                "All the king's horses and all the king's men",
                "Couldn't put Humpty together again"
        };
   // random class for random delay..
        Random random = new Random();
        for(int i=0; i< payload.length; i++) {
            message.write(payload[i]);
            // loop through all payloads
            try {
                Thread.sleep(random.nextInt(2000)); // upto two second sleep after writing a message
            } catch(InterruptedException e) {

            }
        }
        message.write("Finished"); 
    }
}

// Reader class or producer class reads messages
class Reader implements Runnable {
    private Message message;

    public Reader(Message message) {
        this.message = message;
    }

    public void run() {
        Random random = new Random();
        for(String latestPayload = message.read(); !latestPayload.equals("Finished"); // wait for message to say "Finished"
            latestPayload = message.read()) {
            System.out.println(latestPayload);

            try {
                Thread.sleep(random.nextInt(2000));
            } catch(InterruptedException e) {

            }
        }
    }
}


public class Main {

    public static void main(String[] args) {
        Message message = new Message();
        (new Thread(new Writer(message))).start();
        (new Thread(new Reader(message))).start();
    }
}