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
023/**
024 * This is a flag interface that defines the common add/remove listener methods
025 * for classes and interfaces that wish to indicate that they are sources of
026 * ChangeEvents.
027 *
028 * @author Matthew Pocock
029 */
030public interface Changeable {
031  /**
032   * Add a listener that will be informed of all changes.
033   *
034   * @param cl  the ChangeListener to add
035   * @deprecated  use addChangeListener(cl, ChangeType.UNKNOWN)
036   */
037  public void addChangeListener(ChangeListener cl);
038  
039  /**
040   * Add a listener that will be informed of changes of a given type.
041   *
042   * @param cl  the ChangeListener
043   * @param ct  the ChangeType it is to be informed of
044   */
045  public void addChangeListener(ChangeListener cl, ChangeType ct);
046  
047  /**
048   * Remove a listener that was interested in all types of changes.
049   *
050   * @param cl  a ChangeListener to remove
051   * @deprecated  use removeChangeListener(cl, ChangeType.UNKNOWN)
052   */
053  public void removeChangeListener(ChangeListener cl);
054
055  /**
056   * Remove a listener that was interested in a specific types of changes.
057   *
058   * @param cl  a ChangeListener to remove
059   * @param ct  the ChangeType that it was interested in
060   */
061  public void removeChangeListener(ChangeListener cl, ChangeType ct);
062  
063  /**
064   * <p>
065   * A particular ChangeType can never be raised by this Changeable.
066   * </p>
067   *
068   * <p>
069   * If this returns true, then it is guaranteed that change events of this type
070   * (and all child types) can never under any circumstances be fired by this
071   * Changeable instance. If it returns false, that does not mean that this type
072   * of event will or even can be raised, but that it is worth registering
073   * listeners incase.
074   * </p>
075   *
076   * @param ct  the ChangeType to check
077   * @return true if ChangeEvents of this type are guaranteed to never be fired
078   */
079  public boolean isUnchanging(ChangeType ct);
080}