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 *      https://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 */
017
018package org.apache.commons.lang3.function;
019
020import java.util.function.Predicate;
021
022/**
023 * Factory for {@link Predicate}.
024 *
025 * @since 3.18.0
026 */
027public class Predicates {
028
029    private static final Predicate<?> TRUE = t -> true;
030    private static final Predicate<?> FALSE = t -> false;
031
032    /**
033     * Gets the Predicate singleton that always returns false.
034     *
035     * @param <T> the type of the input to the predicate.
036     * @return the Predicate singleton.
037     */
038    @SuppressWarnings("unchecked")
039    // method name cannot be "false".
040    public static <T> Predicate<T> falsePredicate() {
041        return (Predicate<T>) FALSE;
042    }
043
044    /**
045     * Gets the Predicate singleton that always returns true.
046     *
047     * @param <T> the type of the input to the predicate.
048     * @return the Predicate singleton.
049     */
050    @SuppressWarnings("unchecked")
051    // method name cannot be "true".
052    public static <T> Predicate<T> truePredicate() {
053        return (Predicate<T>) TRUE;
054    }
055
056    /**
057     * No instances needed.
058     */
059    private Predicates() {
060        // empty
061    }
062}