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 18 package 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 */ 27 public 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
