1/*
2 *  Licensed to the Apache Software Foundation (ASF) under one or more
3 *  contributor license agreements.  See the NOTICE file distributed with
4 *  this work for additional information regarding copyright ownership.
5 *  The ASF licenses this file to You under the Apache License, Version 2.0
6 *  (the "License"); you may not use this file except in compliance with
7 *  the License.  You may obtain a copy of the License at
8 *
9 *     http://www.apache.org/licenses/LICENSE-2.0
10 *
11 *  Unless required by applicable law or agreed to in writing, software
12 *  distributed under the License is distributed on an "AS IS" BASIS,
13 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 *  See the License for the specific language governing permissions and
15 *  limitations under the License.
16 */
17
18package java.util;
19
20
21/**
22 * {@code Observer} is the interface to be implemented by objects that
23 * receive notification of updates on an {@code Observable} object.
24 *
25 * @see Observable
26 */
27public interface Observer {
28
29    /**
30     * This method is called if the specified {@code Observable} object's
31     * {@code notifyObservers} method is called (because the {@code Observable}
32     * object has been updated.
33     *
34     * @param observable
35     *            the {@link Observable} object.
36     * @param data
37     *            the data passed to {@link Observable#notifyObservers(Object)}.
38     */
39    void update(Observable observable, Object data);
40}
41