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}