/*
 * A Java program that generates a custom event.
 * Based on the javax.swing.event.EventListener documentation.
 *
 * Ben Bederson, February 20, 2002
 */

import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.event.*;

class AlarmEvent extends AWTEvent {
    static public int ALARM_RANG = 1;

    private int nrings = 0;

    public AlarmEvent(Object source, int id, int nrings) {
	super(source, id);
	this.nrings = nrings;
    }

    public int getNumRings() {
	return nrings;
    }
}

interface AlarmListener extends EventListener {
    public void alarmRang(AlarmEvent e);
}

public class AlarmClock {
    EventListenerList listenerList = new EventListenerList();
    AlarmEvent alarmEvent = null;

    public void addAlarmListener(AlarmListener l) {
	listenerList.add(AlarmListener.class, l);
    }

    public void removeAlarmListener(AlarmListener l) {
	listenerList.remove(AlarmListener.class, l);
    }

    // Notify all listeners that have registered interest for
    // notification on this event type.  The event instance 
    // is lazily created using the parameters passed into 
    // the fire method.
    protected void fireAlarmRang(int nrings) {
	// Guaranteed to return a non-null array
	Object[] listeners = listenerList.getListenerList();
	// Process the listeners last to first, notifying
	// those that are interested in this event
	for (int i = listeners.length-2; i>=0; i-=2) {
	    if (listeners[i]==AlarmListener.class) {
		// Lazily create the event:
		if (alarmEvent == null) {
		    alarmEvent = new AlarmEvent(this, AlarmEvent.ALARM_RANG, nrings);
		}
		((AlarmListener)listeners[i+1]).alarmRang(alarmEvent);
	    }
	}
    }

    public void forceAlarm() {
	fireAlarmRang(3);
    }

    static public void main(String[] args) {
	AlarmClock clock = new AlarmClock();
	clock.addAlarmListener(new AlarmListener() {
		public void alarmRang(AlarmEvent e) {
		    System.out.println("alarm!  " + e.getNumRings() + " rings");
		}
	    });

	clock.forceAlarm();
    }
}