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  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.  Oracle designates this

  * particular file as subject to the "Classpath" exception as provided

  * by Oracle in the LICENSE file that accompanied this code.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

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 package java.util;

 /**

  * An iterator over a collection.  {@code Iterator} takes the place of

  * {@link Enumeration} in the Java Collections Framework.  Iterators

  * differ from enumerations in two ways:

  *

  * <ul>

  *      <li> Iterators allow the caller to remove elements from the

  *           underlying collection during the iteration with well-defined

  *           semantics.

  *      <li> Method names have been improved.

  * </ul>

  *

  * <p>This interface is a member of the

  * <a href="{@docRoot}/../technotes/guides/collections/index.html">

  * Java Collections Framework</a>.

  *

  * @param <E> the type of elements returned by this iterator

  *

  * @author  Josh Bloch

  * @see Collection

  * @see ListIterator

  * @see Iterable

  * @since 1.2

  */

 public interface Iterator<E> {

     /**

      * Returns {@code true} if the iteration has more elements.

      * (In other words, returns {@code true} if {@link #next} would

      * return an element rather than throwing an exception.)

      *

      * @return {@code true} if the iteration has more elements

      */

     boolean hasNext();

     /**

      * Returns the next element in the iteration.

      *

      * @return the next element in the iteration

      * @throws NoSuchElementException if the iteration has no more elements

      */

     E next();

     /**

      * Removes from the underlying collection the last element returned

      * by this iterator (optional operation).  This method can be called

      * only once per call to {@link #next}.  The behavior of an iterator

      * is unspecified if the underlying collection is modified while the

      * iteration is in progress in any way other than by calling this

      * method.

      *

      * @throws UnsupportedOperationException if the {@code remove}

      *         operation is not supported by this iterator

      *

      * @throws IllegalStateException if the {@code next} method has not

      *         yet been called, or the {@code remove} method has already

      *         been called after the last call to the {@code next}

      *         method

      */

     void remove();

 }