rev 11962 : 8072726: add adapter to convert Enumeration to Iterator
Reviewed-by: XXX

   1 /*
   2  * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.util;
  27 
  28 import java.util.function.Consumer;
  29 
  30 /**
  31  * An iterator over a collection.  {@code Iterator} takes the place of
  32  * {@link Enumeration} in the Java Collections Framework.  Iterators
  33  * differ from enumerations in two ways:
  34  *
  35  * <ul>
  36  *      <li> Iterators allow the caller to remove elements from the
  37  *           underlying collection during the iteration with well-defined
  38  *           semantics.
  39  *      <li> Method names have been improved.
  40  * </ul>
  41  *
  42  * <p>This interface is a member of the
  43  * <a href="{@docRoot}/../technotes/guides/collections/index.html">
  44  * Java Collections Framework</a>.
  45  *




  46  * @param <E> the type of elements returned by this iterator
  47  *
  48  * @author  Josh Bloch
  49  * @see Collection
  50  * @see ListIterator
  51  * @see Iterable
  52  * @since 1.2
  53  */
  54 public interface Iterator<E> {
  55     /**
  56      * Returns {@code true} if the iteration has more elements.
  57      * (In other words, returns {@code true} if {@link #next} would
  58      * return an element rather than throwing an exception.)
  59      *
  60      * @return {@code true} if the iteration has more elements
  61      */
  62     boolean hasNext();
  63 
  64     /**
  65      * Returns the next element in the iteration.
  66      *
  67      * @return the next element in the iteration
  68      * @throws NoSuchElementException if the iteration has no more elements
  69      */
  70     E next();
  71 
  72     /**
  73      * Removes from the underlying collection the last element returned
  74      * by this iterator (optional operation).  This method can be called
  75      * only once per call to {@link #next}.  The behavior of an iterator
  76      * is unspecified if the underlying collection is modified while the
  77      * iteration is in progress in any way other than by calling this
  78      * method.
  79      *
  80      * @implSpec
  81      * The default implementation throws an instance of
  82      * {@link UnsupportedOperationException} and performs no other action.
  83      *
  84      * @throws UnsupportedOperationException if the {@code remove}
  85      *         operation is not supported by this iterator
  86      *
  87      * @throws IllegalStateException if the {@code next} method has not
  88      *         yet been called, or the {@code remove} method has already
  89      *         been called after the last call to the {@code next}
  90      *         method
  91      */
  92     default void remove() {
  93         throw new UnsupportedOperationException("remove");
  94     }
  95 
  96     /**
  97      * Performs the given action for each remaining element until all elements
  98      * have been processed or the action throws an exception.  Actions are
  99      * performed in the order of iteration, if that order is specified.
 100      * Exceptions thrown by the action are relayed to the caller.
 101      *
 102      * @implSpec
 103      * <p>The default implementation behaves as if:
 104      * <pre>{@code
 105      *     while (hasNext())
 106      *         action.accept(next());
 107      * }</pre>
 108      *
 109      * @param action The action to be performed for each element
 110      * @throws NullPointerException if the specified action is null
 111      * @since 1.8
 112      */
 113     default void forEachRemaining(Consumer<? super E> action) {
 114         Objects.requireNonNull(action);
 115         while (hasNext())
 116             action.accept(next());
 117     }
 118 }
--- EOF ---