    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 * @param <T> the type of the input to the predicate.
    027 * @since 3.0
    028 */
    029public final class NotNullPredicate<T> extends AbstractPredicate<T> implements 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<>();
    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    public static <T> Predicate<T> notNullPredicate() {
    046        return INSTANCE;
    047    }
    048
    049    /**
    050     * Restricted constructor.
    051     */
    052    private NotNullPredicate() {
    053    }
    054
    055    /**
    056     * Returns the singleton instance.
    057     *
    058     * @return the singleton instance.
    059     */
    060    private Object readResolve() {
    061        return INSTANCE;
    062    }
    063
    064    /**
    065     * Evaluates the predicate returning true if the object does not equal null.
    066     *
    067     * @param object  the object to evaluate
    068     * @return true if not null
    069     */
    070    @Override
    071    public boolean test(final T object) {
    072        return object != null;
    073    }
    074
    075}