Observer/Observable design patter native implementation in Java
package kr5;
import java.util.*;
// This is the observing class.
class Watcher implements Observer {
public void update(Observable obj, Object arg) {
System.out.println("update() called, count is " + ((Integer) arg).intValue());
}
}
//This is the class being observed.
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");
}
}
}
}
class ObserverDemo {
public static void main(String args[]) {
BeingWatched observed = new BeingWatched();
Watcher observing = new Watcher();
/* Add the observing to the list of observers for
observed object. */
observed.addObserver(observing);
observed.counter(10);
}
}
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