org.apache.commons.collections.functors.NullPredicate Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.collections.functors;
import java.io.Serializable;
import org.apache.commons.collections.Predicate;
/**
* Predicate implementation that returns true if the input is null.
*
* @since Commons Collections 3.0
* @version $Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
*
* @author Stephen Colebourne
*/
public final class NullPredicate implements Predicate, Serializable {
/** Serial version UID */
private static final long serialVersionUID = 7533784454832764388L;
/** Singleton predicate instance */
public static final Predicate INSTANCE = new NullPredicate();
/**
* Factory returning the singleton instance.
*
* @return the singleton instance
* @since Commons Collections 3.1
*/
public static Predicate getInstance() {
return INSTANCE;
}
/**
* Restricted constructor.
*/
private NullPredicate() {
super();
}
/**
* Evaluates the predicate returning true if the input is null.
*
* @param object the input object
* @return true if input is null
*/
public boolean evaluate(Object object) {
return (object == null);
}
}