EventListenerList.java Source code

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Here is the source code for EventListenerList.java

Source

/**
 * The utillib library.
 * More information is available at http://www.jinchess.com/.
 * Copyright (C) 2002 Alexander Maryanovsky.
 * All rights reserved.
 *
 * The utillib library is free software; you can redistribute
 * it and/or modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * The utillib library is distributed in the hope that it will
 * be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser
 * General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with utillib library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

import java.util.EventListener;
import java.lang.reflect.Array;

/**
 * A convenient storage place for Listeners. The listeners are stored in the
 * same manner as in javax.swing.event.EventListenerList.
 * <STRONG>Note:</STRONG> This class is not thread safe.
 */

public class EventListenerList {

    /**
     * The array where we keep the listeners and their types.
     */

    private Object[] listenerList = new Object[0];

    /**
     * Adds the given listener as a listener of the given type.
     */

    public void add(Class listenerType, EventListener listener) {
        if (listener == null)
            return;
        if (!listenerType.isInstance(listener))
            throw new IllegalArgumentException("The listener is not an instance of the listener class.");

        Object[] tempArr = new Object[listenerList.length + 2];
        System.arraycopy(listenerList, 0, tempArr, 0, listenerList.length);

        tempArr[tempArr.length - 2] = listenerType;
        tempArr[tempArr.length - 1] = listener;

        listenerList = tempArr;
    }

    /**
     * Removes the given listener as a listener of the specified type.
     */

    public void remove(Class listenerType, EventListener listener) {
        if (listener == null)
            return;
        if (!listenerType.isInstance(listener))
            throw new IllegalArgumentException("The listener is not an instance of the listener class.");

        for (int i = 0; i < listenerList.length; i += 2) {
            if ((listenerList[i] == listenerType) && (listenerList[i + 1].equals(listener))) {
                Object[] tempArr = new Object[listenerList.length - 2];
                System.arraycopy(listenerList, 0, tempArr, 0, i);
                System.arraycopy(listenerList, i + 2, tempArr, i, listenerList.length - i - 2);
                listenerList = tempArr;
                return;
            }
        }
    }

    /**
     * Returns the total number of listeners for this listener list.
     */

    public int getListenerCount() {
        return listenerList.length;
    }

    /**
     * Returns the amount of listeners of the specified type in this listener
     * list.
     */

    public int getListenerCount(Class listenerType) {
        int count = 0;
        for (int i = 0; i < listenerList.length; i += 2) {
            if (listenerList[i] == listenerType)
                count++;
        }
        return count;
    }

    /**
     * Returns an array containing all the listeners in this listener list. The
     * array contains listeners and their types in the following format: the
     * element at index 2*N is the type of the listener at index 2*N+1
     * <B>WARNING!!!</B> Absolutely NO modification of the data contained in this array
     * should be made -- if any such manipulation is necessary, it should be done on a
     * copy of the array returned rather than the array itself.
     */

    public Object[] getListenerList() {
        return listenerList;
    }

    /**
     * Returns an array of listeners registered as the listeners of the given
     * type. Note that the returned array is an array of the actual given type
     * so it can be safely casted to that type once instead of casting each of the
     * listener.
     */

    public EventListener[] getListeners(Class listenerType) {
        EventListener[] listeners = (EventListener[]) Array.newInstance(listenerType,
                getListenerCount(listenerType));
        int count = 0;
        for (int i = 0; i < listenerList.length; i += 2) {
            if (listenerType == listenerList[i])
                listeners[count++] = (EventListener) listenerList[i + 1];
        }
        return listeners;
    }

}