001/*
002 * Copyright 2010-2015 Institut Pasteur.
003 * 
004 * This file is part of Icy.
005 * 
006 * Icy is free software: you can redistribute it and/or modify
007 * it under the terms of the GNU General Public License as published by
008 * the Free Software Foundation, either version 3 of the License, or
009 * (at your option) any later version.
010 * 
011 * Icy is distributed in the hope that it will be useful,
012 * but WITHOUT ANY WARRANTY; without even the implied warranty of
013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
014 * GNU General Public License for more details.
015 * 
016 * You should have received a copy of the GNU General Public License
017 * along with Icy. If not, see <http://www.gnu.org/licenses/>.
018 */
019package icy.common.listener.weak;
020
021import java.lang.ref.WeakReference;
022
023/**
024 * Base weak listener class.
025 * 
026 * @author Stephane
027 */
028public abstract class WeakListener<T>
029{
030    private final WeakReference<T> listenerRef;
031
032    public WeakListener(T listener)
033    {
034        super();
035
036        listenerRef = new WeakReference<T>(listener);
037    }
038
039    public T getListener(Object source)
040    {
041        final T listener = listenerRef.get();
042
043        // no more listener --> remove weak object from list
044        if (listener == null)
045            removeListener(source);
046
047        return listener;
048    }
049
050    public T getListener()
051    {
052        return getListener(null);
053    }
054
055    public abstract void removeListener(Object source);
056}