01: /*
02: * Licensed to the Apache Software Foundation (ASF) under one or more
03: * contributor license agreements. See the NOTICE file distributed with
04: * this work for additional information regarding copyright ownership.
05: * The ASF licenses this file to You under the Apache License, Version 2.0
06: * (the "License"); you may not use this file except in compliance with
07: * the License. You may obtain a copy of the License at
08: *
09: * 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:
18: package java.util;
19:
20: /**
21: * Observer must be implemented by objects which are added to an Observable.
22: */
23: public interface Observer {
24:
25: /**
26: * When the specified observable object's <code>notifyObservers</code>
27: * method is called and the observable object has changed, this method is
28: * called.
29: *
30: * @param observable
31: * the observable object
32: * @param data
33: * the data passed to <code>notifyObservers</code>
34: */
35: void update(Observable observable, Object data);
36: }
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