message between threads

How do I send a message from Consumer to Producer when Consumer's i
reaches 50
The message should be displayed and notify should be stopped to do
further execution.

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class Q {
    int n;
    int b;
    boolean valueSet = false;

    synchronized int get(int b) {
        while(!valueSet)
            try {
                wait();
            } catch(InterruptedException ie) {
                System.out.println("Exception caught");
            }
            this. b = b;
            System.out.println("got n : " + n);
            System.out.println("got b : " + b);
            valueSet = false;
            notify();
            return n;

    }

    synchronized void put(int n) {
        while(valueSet)
            try {
                wait();
            } catch(InterruptedException ie) {
                System.out.println("Exception caught");
            }
            this.n = n;

            valueSet = true;
            System.out.println("Put: " + n);
            notify();
    }
}

class Producer implements Runnable {
    Q q;
    Producer(Q q) {
        this.q = q;
        new Thread(this, "Producer").start();
    }
    public void run() {
        //throw new UnsupportedOperationException("Not supported
yet.");
        int i = 0;
        while(true) {
            q.put(i++);
        }
    }

}

class Consumer implements Runnable {
    Q q;
    Consumer(Q q) {
        this.q = q;
        new Thread(this, "Consumer").start();
    }
    public void run() {
        //throw new UnsupportedOperationException("Not supported
yet.");
        int i=100;
        while(true) {
            q.get(i);
            i = i-1;
        }
    }
}
public class Main {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        Q q = new Q();
        new Producer(q);
        new Consumer(q);
        System.out.println("Press Control-c to stop");
    }
}
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Any help
Thanks
Pradyut
http://pradyut.tk
India