01: /* ========================================================================
02: * JCommon : a free general purpose class library for the Java(tm) platform
03: * ========================================================================
04: *
05: * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
06: *
07: * Project Info: http://www.jfree.org/jcommon/index.html
08: *
09: * 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;
46:
47: /**
48: * Protects an given iterator by preventing calls to remove().
49: *
50: * @author Thomas Morgner
51: */
52: public class ReadOnlyIterator implements Iterator {
53:
54: /** The base iterator which we protect. */
55: private Iterator 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 it) {
63: if (it == null) {
64: throw new NullPointerException("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 next() {
87: return this .base.next();
88: }
89:
90: /**
91: * Throws <code>UnsupportedOperationException</code>.
92: */
93: public void remove() {
94: throw new UnsupportedOperationException();
95: }
96: }
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