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/* Iterator.java -- Interface for iterating over collections

   Copyright (C) 1998, 2001, 2004, 2005 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

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GNU Classpath 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

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02110-1301 USA.

Linking this library statically or dynamically with other modules is

making a combined work based on this library.  Thus, the terms and

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As a special exception, the copyright holders of this library give you

permission to link this library with independent modules to produce an

executable, regardless of the license terms of these independent

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terms of your choice, provided that you also meet, for each linked

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exception statement from your version. */

package java.util;

/**

 * An object which iterates over a collection. An Iterator is used to return

 * the items once only, in sequence, by successive calls to the next method.

 * It is also possible to remove elements from the underlying collection by

 * using the optional remove method. Iterator is intended as a replacement

 * for the Enumeration interface of previous versions of Java, which did not

 * have the remove method and had less conveniently named methods.

 *

 * @author Original author unknown

 * @author Eric Blake (ebb9@email.byu.edu)

 * @see Collection

 * @see ListIterator

 * @see Enumeration

 * @since 1.2

 * @status updated to 1.4

 */

public interface Iterator<E>

{

  /**

   * Tests whether there are elements remaining in the collection. In other

   * words, calling <code>next()</code> will not throw an exception.

   *

   * @return true if there is at least one more element in the collection

   */

  boolean hasNext();

  /**

   * Obtain the next element in the collection.

   *

   * @return the next element in the collection

   * @throws NoSuchElementException if there are no more elements

   */

  E next();

  /**

   * Remove from the underlying collection the last element returned by next

   * (optional operation). This method can be called only once after each

   * call to <code>next()</code>. It does not affect what will be returned

   * by subsequent calls to next.

   *

   * @throws IllegalStateException if next has not yet been called or remove

   *         has already been called since the last call to next.

   * @throws UnsupportedOperationException if this Iterator does not support

   *         the remove operation.

   */

  void remove();

}