Les even java

package toto;

import java.util.EventObject;

public class TotoEvent extends EventObject
{
	private static final long serialVersionUID = 1;

	private final Object x0;
	private final Object x;
	
	public TotoEvent(Object source, Object x0, Object x)
	{
		super(source);
		this.x0 = x0;
		this.x = x;
	}
	
	public Object getX0()
	{
		return x0;
	}
	
	public Object getX()
	{
		return x;
	}
}

//---------

package toto;

import java.util.EventListener;

public interface TotoListener extends EventListener
{
	void setCalled(TotoEvent e);
}

//---------

package toto;

import javax.swing.event.EventListenerList;

public class Toto
{
	private final EventListenerList listeners = new EventListenerList();
	
	private Object x;
	
	public Toto(Object o)
	{
		x = o;
	}
	
	public void set(Object o)
	{
		Object x0=x;
		x=o;
		fireSetCalled(new TotoEvent(this,x0,x));
	}
	
	public void addTotoListener(TotoListener listener)
	{
		listeners.add(TotoListener.class, listener);
	}
	
	public void removeTotoListener(TotoListener listener) 
	{
		listeners.remove(TotoListener.class, listener);
 	}
	
	protected TotoListener[] getTotoListeners() 
	{
		return listeners.getListeners(TotoListener.class);
	}
	
	protected void fireSetCalled(TotoEvent e)
	{
		for (TotoListener listener : getTotoListeners())
			listener.setCalled(e);
	}
}

//---------

package toto;

import toto.Toto;
import toto.TotoEvent;
import toto.TotoListener;

public class TestToto
{
	public static void main(String...args)
	{
		Toto t = new Toto(null);
		
		t.addTotoListener(new TotoListener()
		{
			@Override
			public void setCalled(TotoEvent e)
			{
				System.out.println("La valeur "+e.getX0()+" a été remplacée par "+e.getX());
			}
		});
		
		t.set("bubulle");
		t.set(42);
	}
}