// License: GPL. For details, see LICENSE file.
package org.openstreetmap.josm.gui.util;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.event.EventListenerList;
/**
* Replacement to {@code java.util.Observable} class, deprecated with Java 9.
* @since 10210
*/
public class ChangeNotifier {
/** Stores the listeners on this model. */
private final EventListenerList listenerList = new EventListenerList();
/**
* Only one {@code ChangeEvent} is needed per button model
* instance since the event's only state is the source property.
* The source of events generated is always "this".
*/
private ChangeEvent changeEvent;
/**
* Adds a {@code ChangeListener}.
* @param l the listener to add
*/
public final void addChangeListener(ChangeListener l) {
listenerList.add(ChangeListener.class, l);
}
/**
* Removes a {@code ChangeListener}.
* @param l the listener to add
*/
public final void removeChangeListener(ChangeListener l) {
listenerList.remove(ChangeListener.class, l);
}
/**
* Notifies all listeners that have registered interest for notification on this event type.
* The event instance is created lazily.
*/
protected final void fireStateChanged() {
// 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] == ChangeListener.class) {
// Lazily create the event:
if (changeEvent == null)
changeEvent = new ChangeEvent(this);
((ChangeListener) listeners[i+1]).stateChanged(changeEvent);
}
}
}
}