content: /*
   * Copyright (C) 2007 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package android.database;
  
  /**
   * A specialization of {@link Observable} for {@link DataSetObserver}
   * that provides methods for sending notifications to a list of
   * {@link DataSetObserver} objects.
   */
  public class DataSetObservable extends Observable<DataSetObserver> {
      /**
       * Invokes {@link DataSetObserver#onChanged} on each observer.
       * Called when the contents of the data set have changed.  The recipient
       * will obtain the new contents the next time it queries the data set.
       */
      public void notifyChanged() {
          synchronized(mObservers) {
              // since onChanged() is implemented by the app, it could do anything, including
              // removing itself from {@link mObservers} - and that could cause problems if
              // an iterator is used on the ArrayList {@link mObservers}.
              // to avoid such problems, just march thru the list in the reverse order.
              for (int i = mObservers.size() - 1; i >= 0; i--) {
                  mObservers.get(i).onChanged();
              }
          }
      }
  
      /**
       * Invokes {@link DataSetObserver#onInvalidated} on each observer.
       * Called when the data set is no longer valid and cannot be queried again,
       * such as when the data set has been closed.
       */
      public void notifyInvalidated() {
          synchronized (mObservers) {
              for (int i = mObservers.size() - 1; i >= 0; i--) {
                  mObservers.get(i).onInvalidated();
              }
          }
      }
  }
  