NullChangeNotifier.java

/*******************************************************************************
 * Copyright (c) 1998, 2015 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.tools.workbench.utility.events;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.Serializable;

/**
 * Null implementation of ChangeNotifier interface: Do nothing.
 */
public final class NullChangeNotifier
    implements ChangeNotifier, Serializable
{
    // singleton
    private static ChangeNotifier INSTANCE;

    private static final long serialVersionUID = 1L;


    /**
     * Return the singleton.
     */
    public synchronized static ChangeNotifier instance() {
        if (INSTANCE == null) {
            INSTANCE = new NullChangeNotifier();
        }
        return INSTANCE;
    }

    /**
     * Ensure non-instantiability.
     */
    private NullChangeNotifier() {
        super();
    }

    public void stateChanged(StateChangeListener listener, StateChangeEvent event) {
        // do nothing
    }

    public void propertyChange(PropertyChangeListener listener, PropertyChangeEvent event) {
        // do nothing
    }

    public void itemsAdded(CollectionChangeListener listener, CollectionChangeEvent event) {
        // do nothing
    }

    public void itemsRemoved(CollectionChangeListener listener, CollectionChangeEvent event) {
        // do nothing
    }

    public void collectionChanged(CollectionChangeListener listener, CollectionChangeEvent event) {
        // do nothing
    }

    public void itemsAdded(ListChangeListener listener, ListChangeEvent event) {
        // do nothing
    }

    public void itemsRemoved(ListChangeListener listener, ListChangeEvent event) {
        // do nothing
    }

    public void itemsReplaced(ListChangeListener listener, ListChangeEvent event) {
        // do nothing
    }

    public void listChanged(ListChangeListener listener, ListChangeEvent event) {
        // do nothing
    }

    public void nodeAdded(TreeChangeListener listener, TreeChangeEvent event) {
        // do nothing
    }

    public void nodeRemoved(TreeChangeListener listener, TreeChangeEvent event) {
        // do nothing
    }

    public void treeChanged(TreeChangeListener listener, TreeChangeEvent event) {
        // do nothing
    }

    /**
     * Serializable singleton support
     */
    private Object readResolve() {
        return instance();
    }

}