/*
This file is part of Cyclos (www.cyclos.org).
A project of the Social Trade Organisation (www.socialtrade.org).
Cyclos is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
Cyclos 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with Cyclos; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package nl.strohalm.cyclos.utils.cache;
import java.io.Serializable;
/**
* Some caches don't support adding null values. So, this class is used
*
* @author luis
*/
public class NullValue implements Serializable {
private static final long serialVersionUID = -3479308521144563997L;
private static final NullValue INSTANCE = new NullValue();
public static NullValue getInstance() {
return INSTANCE;
}
/**
* Returns null if the given object is a NullValue, or the same object otherwise
*/
public static Object nullIfNullValue(final Object object) {
if (object instanceof NullValue) {
return null;
}
return object;
}
/**
* Returns a NullValue if the given object is null, or the same object otherwise
*/
public static Object nullValueIfNull(final Object object) {
if (object == null) {
return getInstance();
}
return object;
}
private NullValue() {
}
protected Object readResolve() {
return INSTANCE;
}
}