001    /*
002     * Copyright 2006 Google Inc.
003     * 
004     * Licensed under the Apache License, Version 2.0 (the "License"); you may not
005     * use this file except in compliance with the License. You may obtain a copy of
006     * the License at
007     * 
008     * http://www.apache.org/licenses/LICENSE-2.0
009     * 
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
012     * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
013     * License for the specific language governing permissions and limitations under
014     * the License.
015     */
016    package com.google.gwt.user.client;
017    
018    /**
019     * Implement this interface to receive notification of changes to the browser
020     * history state.  It is used with {@link com.google.gwt.user.client.History}.
021     */
022    public interface HistoryListener {
023    
024      /**
025       * Fired when the user clicks the browser's 'back' or 'forward' buttons.
026       * 
027       * @param historyToken the token representing the current history state
028       */
029      void onHistoryChanged(String historyToken);
030    }