001 /* Observer.java -- an object that will be informed of changes in an Observable 002 Copyright (C) 1998, 1999, 2001, 2002, 2005 Free Software Foundation, Inc. 003 004 This file is part of GNU Classpath. 005 006 GNU Classpath is free software; you can redistribute it and/or modify 007 it under the terms of the GNU General Public License as published by 008 the Free Software Foundation; either version 2, or (at your option) 009 any later version. 010 011 GNU Classpath is distributed in the hope that it will be useful, but 012 WITHOUT ANY WARRANTY; without even the implied warranty of 013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014 General Public License for more details. 015 016 You should have received a copy of the GNU General Public License 017 along with GNU Classpath; see the file COPYING. If not, write to the 018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 019 02110-1301 USA. 020 021 Linking this library statically or dynamically with other modules is 022 making a combined work based on this library. Thus, the terms and 023 conditions of the GNU General Public License cover the whole 024 combination. 025 026 As a special exception, the copyright holders of this library give you 027 permission to link this library with independent modules to produce an 028 executable, regardless of the license terms of these independent 029 modules, and to copy and distribute the resulting executable under 030 terms of your choice, provided that you also meet, for each linked 031 independent module, the terms and conditions of the license of that 032 module. An independent module is a module which is not derived from 033 or based on this library. If you modify this library, you may extend 034 this exception to your version of the library, but you are not 035 obligated to do so. If you do not wish to do so, delete this 036 exception statement from your version. */ 037 038 039 package java.util; 040 041 /** 042 * Interface that is implemented when a class wants to be informed of changes 043 * in Observable objects. 044 * 045 * @author Warren Levy (warrenl@cygnus.com) 046 * @see Observable 047 * @status updated to 1.4 048 */ 049 public interface Observer 050 { 051 /** 052 * This method is called whenever the observable object changes, and has 053 * called <code>notifyObservers</code>. The Observable object can pass 054 * arbitrary information in the second parameter. 055 * 056 * @param observable the Observable object that changed 057 * @param arg arbitrary information, usually relating to the change 058 */ 059 void update(Observable observable, Object arg); 060 }