public忽悠了不少人啊
当有人想继承org.eclipse.draw2d.graph中的GraphVisitor类时，却惊奇的发现import不进来，而且jar包里确实有这个包，这个时候不妨看看它的源代码吧，
/******************************************************************************* * Copyright (c) 2003, 2005 IBM Corporation and others. * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html * * Contributors: * IBM Corporation - initial API and implementation *******************************************************************************/package org.eclipse.draw2d.graph;/** * Performs some action on a Graph. * @author Randy Hudson * @since 2.1.2 */abstract class GraphVisitor {/** * Act on the given directed graph. * @param g the graph */void visit(DirectedGraph g) { }/** * Called in reverse order of visit. * @since 3.1 * @param g the graph to act upon */void revisit(DirectedGraph g) { }}