/*******************************************************************************
 * Copyright (c) 2000, 2011 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.widgets;


/**
 * Implementers of <code>Listener</code> provide a simple
 * <code>handleEvent()</code> method that is used internally
 * by SWT to dispatch events.
 * <p>
 * After creating an instance of a class that implements this interface
 * it can be added to a widget using the
 * <code>addListener(int eventType, Listener handler)</code> method and
 * removed using the
 * <code>removeListener (int eventType, Listener handler)</code> method.
 * When the specified event occurs, <code>handleEvent(...)</code> will
 * be sent to the instance.
 * </p>
 * <p>
 * Classes which implement this interface are described within SWT as
 * providing the <em>untyped listener</em> API. Typically, widgets will
 * also provide a higher-level <em>typed listener</em> API, that is based
 * on the standard <code>java.util.EventListener</code> pattern.
 * </p>
 * <p>
 * Note that, since all internal SWT event dispatching is based on untyped
 * listeners, it is simple to build subsets of SWT for use on memory
 * constrained, small footprint devices, by removing the classes and
 * methods which implement the typed listener API.
 * </p>
 *
 * @see Widget#addListener
 * @see java.util.EventListener
 * @see org.eclipse.swt.events
 */
public interface Listener {

/**
 * Sent when an event that the receiver has registered for occurs.
 *
 * @param event the event which occurred
 */
void handleEvent (Event event);
}
