01: /*
02: * @(#)Observer.java 1.23 06/10/10
03: *
04: * Copyright 1990-2006 Sun Microsystems, Inc. All Rights Reserved.
05: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
06: *
07: * This program is free software; you can redistribute it and/or
08: * modify it under the terms of the GNU General Public License version
09: * 2 only, as published by the Free Software Foundation.
10: *
11: * This program is distributed in the hope that it will be useful, but
12: * WITHOUT ANY WARRANTY; without even the implied warranty of
13: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14: * General Public License version 2 for more details (a copy is
15: * included at /legal/license.txt).
16: *
17: * You should have received a copy of the GNU General Public License
18: * version 2 along with this work; if not, write to the Free Software
19: * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20: * 02110-1301 USA
21: *
22: * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
23: * Clara, CA 95054 or visit www.sun.com if you need additional
24: * information or have any questions.
25: *
26: */
27: package java.util;
28:
29: /**
30: * A class can implement the <code>Observer</code> interface when it
31: * wants to be informed of changes in observable objects.
32: *
33: * @author Chris Warth
34: * @version 1.16, 02/02/00
35: * @see java.util.Observable
36: * @since JDK1.0
37: */
38: public interface Observer {
39: /**
40: * This method is called whenever the observed object is changed. An
41: * application calls an <tt>Observable</tt> object's
42: * <code>notifyObservers</code> method to have all the object's
43: * observers notified of the change.
44: *
45: * @param o the observable object.
46: * @param arg an argument passed to the <code>notifyObservers</code>
47: * method.
48: */
49: void update(Observable o, Object arg);
50: }
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