    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 always returns true.
    025 *
    026 * @since 3.0
    027 */
    028public final class TruePredicate<T> implements Predicate<T>, Serializable {
    029
    030    /** Serial version UID */
    031    private static final long serialVersionUID = 3374767158756189740L;
    032
    033    /** Singleton predicate instance */
    034    @SuppressWarnings("rawtypes")
    035    public static final Predicate INSTANCE = new TruePredicate<>();
    036
    037    /**
    038     * Factory returning the singleton instance.
    039     *
    040     * @param <T> the type that the predicate queries
    041     * @return the singleton instance
    042     * @since 3.1
    043     */
    044    public static <T> Predicate<T> truePredicate() {
    045        return INSTANCE;
    046    }
    047
    048    /**
    049     * Restricted constructor.
    050     */
    051    private TruePredicate() {
    052    }
    053
    054    /**
    055     * Evaluates the predicate returning true always.
    056     *
    057     * @param object  the input object
    058     * @return true always
    059     */
    060    @Override
    061    public boolean evaluate(final T object) {
    062        return true;
    063    }
    064
    065    private Object readResolve() {
    066        return INSTANCE;
    067    }
    068
    069}