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Java > Open Source Codes > org > jfree > util > ReadOnlyIterator


1 /* ========================================================================
2  * JCommon : a free general purpose class library for the Java(tm) platform
3  * ========================================================================
4  *
5  * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
6  *
7  * Project Info: http://www.jfree.org/jcommon/index.html
8  *
9  * This library is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU Lesser General Public License as published by
11  * the Free Software Foundation; either version 2.1 of the License, or
12  * (at your option) any later version.
13  *
14  * This library is distributed in the hope that it will be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17  * License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with this library; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
22  * USA.
23  *
24  * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
25  * in the United States and other countries.]
26  *
27  * ---------------------
28  * ReadOnlyIterator.java
29  * ---------------------
30  * (C)opyright 2003, 2004, by Thomas Morgner and Contributors.
31  *
32  * Original Author: Thomas Morgner;
33  * Contributor(s): -;
34  *
35  * $Id: ReadOnlyIterator.java,v 1.2 2005/10/18 13:24:19 mungady Exp $
36  *
37  * Changes
38  * -------------------------
39  * 18-Jul-2003 : Initial version
40  *
41  */
42
43 package org.jfree.util;
44
45 import java.util.Iterator JavaDoc;
46
47 /**
48  * Protects an given iterator by preventing calls to remove().
49  *
50  * @author Thomas Morgner
51  */
52 public class ReadOnlyIterator implements Iterator JavaDoc {
53
54     /** The base iterator which we protect. */
55     private Iterator JavaDoc base;
56
57     /**
58      * Creates a new read-only iterator for the given iterator.
59      *
60      * @param it the iterator.
61      */
62     public ReadOnlyIterator(final Iterator JavaDoc it) {
63         if (it == null) {
64             throw new NullPointerException JavaDoc("Base iterator is null.");
65         }
66         this.base = it;
67     }
68
69     /**
70      * Returns <tt>true</tt> if the iteration has more elements. (In other
71      * words, returns <tt>true</tt> if <tt>next</tt> would return an element
72      * rather than throwing an exception.)
73      *
74      * @return <tt>true</tt> if the iterator has more elements.
75      */
76     public boolean hasNext() {
77         return this.base.hasNext();
78     }
79
80     /**
81      * Returns the next element in the iteration.
82      * Throws NoSuchElementException when iteration has no more elements.
83      *
84      * @return the next element in the iteration.
85      */
86     public Object JavaDoc next() {
87         return this.base.next();
88     }
89
90     /**
91      * Throws <code>UnsupportedOperationException</code>.
92      */
93     public void remove() {
94         throw new UnsupportedOperationException JavaDoc();
95     }
96 }
97
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