1 /* 2 * Copyright (C) 2007 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.database; 18 19 /** 20 * A specialization of {@link Observable} for {@link DataSetObserver} 21 * that provides methods for sending notifications to a list of 22 * {@link DataSetObserver} objects. 23 */ 24 public class DataSetObservable extends Observable<DataSetObserver> { 25 /** 26 * Invokes {@link DataSetObserver#onChanged} on each observer. 27 * Called when the contents of the data set have changed. The recipient 28 * will obtain the new contents the next time it queries the data set. 29 */ notifyChanged()30 public void notifyChanged() { 31 synchronized(mObservers) { 32 // since onChanged() is implemented by the app, it could do anything, including 33 // removing itself from {@link mObservers} - and that could cause problems if 34 // an iterator is used on the ArrayList {@link mObservers}. 35 // to avoid such problems, just march thru the list in the reverse order. 36 for (int i = mObservers.size() - 1; i >= 0; i--) { 37 mObservers.get(i).onChanged(); 38 } 39 } 40 } 41 42 /** 43 * Invokes {@link DataSetObserver#onInvalidated} on each observer. 44 * Called when the data set is no longer valid and cannot be queried again, 45 * such as when the data set has been closed. 46 */ notifyInvalidated()47 public void notifyInvalidated() { 48 synchronized (mObservers) { 49 for (int i = mObservers.size() - 1; i >= 0; i--) { 50 mObservers.get(i).onInvalidated(); 51 } 52 } 53 } 54 } 55