/* An object may be observed by two or more

observers.

*/

import java.util.Observable;

import java.util.Observer;

class TwoObservers {

// This is the first observing class.

static class Watcher1 implements Observer {

public void update(Observable obj, Object arg) {

System.out.println("update() called, count is " + ((Integer) arg).intValue());

}

}

// This is the second observing class.

static class Watcher2 implements Observer {

public void update(Observable obj, Object arg) {

// Ring bell when done

if (((Integer) arg).intValue() == 0)

System.out.println("Done" + '\7');

}

}

// This is the class being observed.

static class BeingWatched extends Observable {

void counter(int period) {

for (; period >= 0; period--) {

setChanged();

notifyObservers(new Integer(period));

try {

Thread.sleep(100);

} catch (InterruptedException e) {

System.out.println("Sleep interrupted");

}

}

}

}

public static void main(String args[]) {

BeingWatched observed = new BeingWatched();

Watcher1 observing1 = new Watcher1();

Watcher2 observing2 = new Watcher2();

// add both observers

observed.addObserver(observing2);

observed.addObserver(observing1);

observed.counter(20);

}

}