/* XXL: The eXtensible and fleXible Library for data processing
Copyright (C) 2000-2011 Prof. Dr. Bernhard Seeger
Head of the Database Research Group
Department of Mathematics and Computer Science
University of Marburg
Germany
This 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 3 of the License, or (at your option) any later version.
This 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 this library; If not, see <http://www.gnu.org/licenses/>.
http://code.google.com/p/xxl/
*/
package xxl.core.predicates;
/**
* This class provides a binary predicate that determines whether two given
* arguments are equal. The <code>invoke</code> method of the predicate is
* based on the {@link Object#equals(Object) equals} method of the class
* {@link Object}. In other words, two arguments <code>a</code> and
* <code>b</code> are not equal when
* (<code>a!=null && !a.equals(b)==true</code>) is true.
*
* @param <P> the type of the predicate's parameters.
*/
public class NotEqual<P> extends AbstractPredicate<P> {
/**
* This instance can be used for getting a default instance of NotEqual. It
* is similar to the <i>Singleton Design Pattern</i> (for further details
* see Creational Patterns, Prototype in <i>Design Patterns: Elements of
* Reusable Object-Oriented Software</i> by Erich Gamma, Richard Helm,
* Ralph Johnson, and John Vlissides) except that there are no mechanisms
* to avoid the creation of other instances of NotEqual.
*/
public static final NotEqual<Object> DEFAULT_INSTANCE = new NotEqual<Object>();
/**
* Returns whether the given arguments are equal or not. In other words,
* returns <code>true</code> if <code>!argument0.equals(argument1)</code>
* returns <code>true</code>. The exact implementation is
* <code><pre>
* return !argument0.equals(argument1);
* </pre></code>
*
* @param argument0 the first argument to the predicate.
* @param argument1 the second argument to the predicate.
* @return <code>true</code> if the given arguments are equal, otherwise
* <code>false</code>.
*/
@Override
public boolean invoke(P argument0, P argument1) {
return !argument0.equals( argument1);
}
}