jaroslav@557: /*
jaroslav@557:  * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
jaroslav@557:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jaroslav@557:  *
jaroslav@557:  * This code is free software; you can redistribute it and/or modify it
jaroslav@557:  * under the terms of the GNU General Public License version 2 only, as
jaroslav@557:  * published by the Free Software Foundation.  Oracle designates this
jaroslav@557:  * particular file as subject to the "Classpath" exception as provided
jaroslav@557:  * by Oracle in the LICENSE file that accompanied this code.
jaroslav@557:  *
jaroslav@557:  * This code is distributed in the hope that it will be useful, but WITHOUT
jaroslav@557:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jaroslav@557:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jaroslav@557:  * version 2 for more details (a copy is included in the LICENSE file that
jaroslav@557:  * accompanied this code).
jaroslav@557:  *
jaroslav@557:  * You should have received a copy of the GNU General Public License version
jaroslav@557:  * 2 along with this work; if not, write to the Free Software Foundation,
jaroslav@557:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jaroslav@557:  *
jaroslav@557:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jaroslav@557:  * or visit www.oracle.com if you need additional information or have any
jaroslav@557:  * questions.
jaroslav@557:  */
jaroslav@557: 
jaroslav@557: package java.util;
jaroslav@557: 
jaroslav@557: /**
jaroslav@557:  * An iterator over a collection.  {@code Iterator} takes the place of
jaroslav@557:  * {@link Enumeration} in the Java Collections Framework.  Iterators
jaroslav@557:  * differ from enumerations in two ways:
jaroslav@557:  *
jaroslav@557:  * <ul>
jaroslav@557:  *      <li> Iterators allow the caller to remove elements from the
jaroslav@557:  *           underlying collection during the iteration with well-defined
jaroslav@557:  *           semantics.
jaroslav@557:  *      <li> Method names have been improved.
jaroslav@557:  * </ul>
jaroslav@557:  *
jaroslav@557:  * <p>This interface is a member of the
jaroslav@557:  * <a href="{@docRoot}/../technotes/guides/collections/index.html">
jaroslav@557:  * Java Collections Framework</a>.
jaroslav@557:  *
jaroslav@557:  * @param <E> the type of elements returned by this iterator
jaroslav@557:  *
jaroslav@557:  * @author  Josh Bloch
jaroslav@557:  * @see Collection
jaroslav@557:  * @see ListIterator
jaroslav@557:  * @see Iterable
jaroslav@557:  * @since 1.2
jaroslav@557:  */
jaroslav@557: public interface Iterator<E> {
jaroslav@557:     /**
jaroslav@557:      * Returns {@code true} if the iteration has more elements.
jaroslav@557:      * (In other words, returns {@code true} if {@link #next} would
jaroslav@557:      * return an element rather than throwing an exception.)
jaroslav@557:      *
jaroslav@557:      * @return {@code true} if the iteration has more elements
jaroslav@557:      */
jaroslav@557:     boolean hasNext();
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Returns the next element in the iteration.
jaroslav@557:      *
jaroslav@557:      * @return the next element in the iteration
jaroslav@557:      * @throws NoSuchElementException if the iteration has no more elements
jaroslav@557:      */
jaroslav@557:     E next();
jaroslav@557: 
jaroslav@557:     /**
jaroslav@557:      * Removes from the underlying collection the last element returned
jaroslav@557:      * by this iterator (optional operation).  This method can be called
jaroslav@557:      * only once per call to {@link #next}.  The behavior of an iterator
jaroslav@557:      * is unspecified if the underlying collection is modified while the
jaroslav@557:      * iteration is in progress in any way other than by calling this
jaroslav@557:      * method.
jaroslav@557:      *
jaroslav@557:      * @throws UnsupportedOperationException if the {@code remove}
jaroslav@557:      *         operation is not supported by this iterator
jaroslav@557:      *
jaroslav@557:      * @throws IllegalStateException if the {@code next} method has not
jaroslav@557:      *         yet been called, or the {@code remove} method has already
jaroslav@557:      *         been called after the last call to the {@code next}
jaroslav@557:      *         method
jaroslav@557:      */
jaroslav@557:     void remove();
jaroslav@557: }