    001    /* ========================================================================
    002     * JCommon : a free general purpose class library for the Java(tm) platform
    003     * ========================================================================
    004     *
    005     * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
    006     *
    007     * Project Info:  http://www.jfree.org/jcommon/index.html
    008     *
    009     * This library is free software; you can redistribute it and/or modify it
    010     * under the terms of the GNU Lesser General Public License as published by
    011     * the Free Software Foundation; either version 2.1 of the License, or
    012     * (at your option) any later version.
    013     *
    014     * This library is distributed in the hope that it will be useful, but
    015     * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    016     * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
    017     * License for more details.
    018     *
    019     * You should have received a copy of the GNU Lesser General Public
    020     * License along with this library; if not, write to the Free Software
    021     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
    022     * USA.
    023     *
    024     * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
    025     * in the United States and other countries.]
    026     *
    027     * ---------------------
    028     * ReadOnlyIterator.java
    029     * ---------------------
    030     * (C)opyright 2003, 2004, by Thomas Morgner and Contributors.
    031     *
    032     * Original Author:  Thomas Morgner;
    033     * Contributor(s):   -;
    034     *
    035     * $Id: ReadOnlyIterator.java,v 1.2 2005/10/18 13:24:19 mungady Exp $
    036     *
    037     * Changes
    038     * -------------------------
    039     * 18-Jul-2003 : Initial version
    040     *
    041     */
    042
    043    package org.jfree.util;
    044
    045    import java.util.Iterator;
    046
    047    /**
    048     * Protects an given iterator by preventing calls to remove().
    049     *
    050     * @author Thomas Morgner
    051     */
    052    public class ReadOnlyIterator implements Iterator {
    053
    054        /** The base iterator which we protect. */
    055        private Iterator base;
    056
    057        /**
    058         * Creates a new read-only iterator for the given iterator.
    059         *
    060         * @param it the iterator.
    061         */
    062        public ReadOnlyIterator(final Iterator it) {
    063            if (it == null) {
    064                throw new NullPointerException("Base iterator is null.");
    065            }
    066            this.base = it;
    067        }
    068
    069        /**
    070         * Returns <tt>true</tt> if the iteration has more elements. (In other
    071         * words, returns <tt>true</tt> if <tt>next</tt> would return an element
    072         * rather than throwing an exception.)
    073         *
    074         * @return <tt>true</tt> if the iterator has more elements.
    075         */
    076        public boolean hasNext() {
    077            return this.base.hasNext();
    078        }
    079
    080        /**
    081         * Returns the next element in the iteration.
    082         * Throws NoSuchElementException when iteration has no more elements.
    083         *
    084         * @return the next element in the iteration.
    085         */
    086        public Object next() {
    087            return this.base.next();
    088        }
    089
    090        /**
    091         * Throws <code>UnsupportedOperationException</code>.
    092         */
    093        public void remove() {
    094            throw new UnsupportedOperationException();
    095        }
    096    }