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 }