java/src/main/com/google/appengine/api/datastore/CallbackContext.java

   1 // Copyright 2011 Google Inc. All Rights Reserved.
   2 package com.google.appengine.api.datastore;
   3
   4 import java.util.List;
   5
   6 /**
   7  * Describes the context in which a callback runs.  The context has access to
   8  * the current transaction (if any), the element that the callback is
   9  * operating on (eg the Entity being put or the Key being deleted), as well as
  10  * all elements being operated on in the operation that triggered the callback..
  11  *
  12  * @param <T> the type of element that the callback is acting on.
  13  *
  14  */
  15 public interface CallbackContext<T> {
  16   /**
  17    * @return An unmodifiable view of the elements involved in the operation
  18    * that triggered the callback..
  19    */
  20   List<T> getElements();
  21
  22   /**
  23    * @return The current transaction, or {@code null} if there is no current
  24    * transaction.
  25    */
  26   Transaction getCurrentTransaction();
  27
  28   /**
  29    * @return The index in the result of {@link #getElements()} of the element
  30    * for which the callback has been invoked.
  31    */
  32   int getCurrentIndex();
  33
  34   /**
  35    * @return The element for which the callback has been invoked.  Shortcut
  36    * for {@code getElements().getCurrentIndex()}.
  37    */
  38   T getCurrentElement();
  39 }