001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.collections4.functors;
018
019import java.io.Serializable;
020
021import org.apache.commons.collections4.Predicate;
022
023/**
024 * Predicate implementation that returns true if the input is not null.
025 *
026 * @since 3.0
027 * @version $Id: NotNullPredicate.html 972421 2015-11-14 20:00:04Z tn $
028 */
029public final class NotNullPredicate<T> implements Predicate<T>, Serializable {
030
031    /** Serial version UID */
032    private static final long serialVersionUID = 7533784454832764388L;
033
034    /** Singleton predicate instance */
035    @SuppressWarnings("rawtypes")
036    public static final Predicate INSTANCE = new NotNullPredicate<Object>();
037
038    /**
039     * Factory returning the singleton instance.
040     *
041     * @param <T> the type that the predicate queries
042     * @return the singleton instance
043     * @since 3.1
044     */
045    @SuppressWarnings("unchecked")
046    public static <T> Predicate<T> notNullPredicate() {
047        return (Predicate<T>) INSTANCE;
048    }
049
050    /**
051     * Restricted constructor.
052     */
053    private NotNullPredicate() {
054        super();
055    }
056
057    /**
058     * Evaluates the predicate returning true if the object does not equal null.
059     *
060     * @param object  the object to evaluate
061     * @return true if not null
062     */
063    public boolean evaluate(final T object) {
064        return object != null;
065    }
066
067    private Object readResolve() {
068        return INSTANCE;
069    }
070
071}