001/*
002 *                    BioJava development code
003 *
004 * This code may be freely distributed and modified under the
005 * terms of the GNU Lesser General Public Licence.  This should
006 * be distributed with the code.  If you do not have a copy,
007 * see:
008 *
009 *      http://www.gnu.org/copyleft/lesser.html
010 *
011 * Copyright for this code is held jointly by the individual
012 * authors.  These should be listed in @author doc comments.
013 *
014 * For more information on the BioJava project and its aims,
015 * or to join the biojava-l mailing list, visit the home page
016 * at:
017 *
018 *      http://www.biojava.org/
019 */
020
021package org.biojava.utils;
022
023import java.util.Collections;
024import java.util.Set;
025
026/**
027 * This is a utility implementation of Changeable that doesn't fire any events
028 * or keep references to any listeners. Use this when you have a final immutable
029 * class and can't be bothered to fill in all those method stubs.
030 *
031 * @author Matthew Pocock
032 * @since 1.3
033 */
034public class Unchangeable
035implements Changeable {
036  public final void addChangeListener(ChangeListener cl) {}
037
038  public final void addChangeListener(ChangeListener cl, ChangeType ct) {}
039
040  public final Set getListeners(ChangeType ct) { return Collections.EMPTY_SET; }
041
042  public final void removeChangeListener(ChangeListener cl) {}
043
044  public final void removeChangeListener(ChangeListener cl, ChangeType ct) {}
045
046  public final void addForwarder(ChangeForwarder cf, ChangeType ct) {}
047
048  public final void removeForwarder(ChangeForwarder cf, ChangeType ct) {}
049
050  public final Set getForwarders(ChangeType ct) { return Collections.EMPTY_SET; }
051
052  public final boolean isUnchanging(ChangeType ct) { return true; }
053}