1 /* 2 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 package java.util.function; 26 27 import java.util.Objects; 28 29 /** 30 * Represents a predicate (boolean-valued function) of one argument. 31 * 32 * <p>This is a <a href="package-summary.html">functional interface</a> 33 * whose functional method is {@link #test(Object)}. 34 * 35 * @param <T> the type of the input to the predicate 36 * 37 * @since 1.8 38 */ 39 @FunctionalInterface 40 public interface Predicate<T> { 41 42 /** 43 * Evaluates this predicate on the given argument. 44 * 45 * @param t the input argument 46 * @return {@code true} if the input argument matches the predicate, 47 * otherwise {@code false} 48 */ test(T t)49 boolean test(T t); 50 51 /** 52 * Returns a composed predicate that represents a short-circuiting logical 53 * AND of this predicate and another. When evaluating the composed 54 * predicate, if this predicate is {@code false}, then the {@code other} 55 * predicate is not evaluated. 56 * 57 * <p>Any exceptions thrown during evaluation of either predicate are relayed 58 * to the caller; if evaluation of this predicate throws an exception, the 59 * {@code other} predicate will not be evaluated. 60 * 61 * @param other a predicate that will be logically-ANDed with this 62 * predicate 63 * @return a composed predicate that represents the short-circuiting logical 64 * AND of this predicate and the {@code other} predicate 65 * @throws NullPointerException if other is null 66 */ and(Predicate<? super T> other)67 default Predicate<T> and(Predicate<? super T> other) { 68 Objects.requireNonNull(other); 69 return (t) -> test(t) && other.test(t); 70 } 71 72 /** 73 * Returns a predicate that represents the logical negation of this 74 * predicate. 75 * 76 * @return a predicate that represents the logical negation of this 77 * predicate 78 */ negate()79 default Predicate<T> negate() { 80 return (t) -> !test(t); 81 } 82 83 /** 84 * Returns a composed predicate that represents a short-circuiting logical 85 * OR of this predicate and another. When evaluating the composed 86 * predicate, if this predicate is {@code true}, then the {@code other} 87 * predicate is not evaluated. 88 * 89 * <p>Any exceptions thrown during evaluation of either predicate are relayed 90 * to the caller; if evaluation of this predicate throws an exception, the 91 * {@code other} predicate will not be evaluated. 92 * 93 * @param other a predicate that will be logically-ORed with this 94 * predicate 95 * @return a composed predicate that represents the short-circuiting logical 96 * OR of this predicate and the {@code other} predicate 97 * @throws NullPointerException if other is null 98 */ or(Predicate<? super T> other)99 default Predicate<T> or(Predicate<? super T> other) { 100 Objects.requireNonNull(other); 101 return (t) -> test(t) || other.test(t); 102 } 103 104 /** 105 * Returns a predicate that tests if two arguments are equal according 106 * to {@link Objects#equals(Object, Object)}. 107 * 108 * @param <T> the type of arguments to the predicate 109 * @param targetRef the object reference with which to compare for equality, 110 * which may be {@code null} 111 * @return a predicate that tests if two arguments are equal according 112 * to {@link Objects#equals(Object, Object)} 113 */ isEqual(Object targetRef)114 static <T> Predicate<T> isEqual(Object targetRef) { 115 return (null == targetRef) 116 ? Objects::isNull 117 : object -> targetRef.equals(object); 118 } 119 } 120