Java tutorial
/******************************************************************************* * 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); }