001    /* JAPI - (Yet another (hopefully) useful) Java API
002     *
003     * Copyright (C) 2004-2006 Christian Hujer
004     *
005     * This program is free software; you can redistribute it and/or
006     * modify it under the terms of the GNU General Public License as
007     * published by the Free Software Foundation; either version 2 of the
008     * License, or (at your option) any later version.
009     *
010     * This program is distributed in the hope that it will be useful, but
011     * WITHOUT ANY WARRANTY; without even the implied warranty of
012     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
013     * General Public License for more details.
014     *
015     * You should have received a copy of the GNU General Public License
016     * along with this program; if not, write to the Free Software
017     * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
018     * 02111-1307, USA.
019     */
020    
021    package net.sf.japi.util;
022    
023    import java.util.Iterator;
024    import java.util.NoSuchElementException;
025    
026    /** An iterator that never returns elements and thus is always empty.
027     * @author <a href="mailto:chris@riedquat.de">Christian Hujer</a>
028     */
029    public class EmptyIterator<T> implements Iterator<T> {
030    
031        /** Create an Empty Iterator.
032         * Please note that this class does not hold any state.
033         * The Constructor only exists for convenient Generics programming.
034         * It makes sense to store an empty iterator somewhere and reuse it, eventually even in a static final variable.
035         */
036        public EmptyIterator() {
037        }
038    
039        /** {@inheritDoc} */
040        public boolean hasNext() {
041            return false;
042        }
043    
044        /** {@inheritDoc} */
045        public T next() throws NoSuchElementException {
046            throw new NoSuchElementException("No more elements");
047        }
048    
049        /** {@inheritDoc} */
050        public void remove() {
051            throw new UnsupportedOperationException();
052        }
053    
054    } // class EmptyIterator