1 /*
   2  * Copyright (c) 2010, 2012 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  * Determines if the input object matches some criteria.
  31  *
  32  * @param <T> the type of input objects to {@code test}
  33  *
  34  * @since 1.8
  35  */
  36 public interface Predicate<T> {
  37 
  38     /**
  39      * Returns {@code true} if the input object matches some criteria.
  40      *
  41      * @param t the input object
  42      * @return {@code true} if the input object matches some criteria, otherwise
  43      * {@code false}
  44      */
  45     public boolean test(T t);
  46 
  47     /**
  48      * Returns a predicate which evaluates to {@code true} only if this
  49      * predicate and the provided predicate both evaluate to {@code true}. If
  50      * this predicate returns {@code false} then the remaining predicate is not
  51      * evaluated.
  52      *
  53      * @return a new predicate which returns {@code true} only if both
  54      * predicates return {@code true}.
  55      */
  56     public default Predicate<T> and(Predicate<? super T> p) {
  57         Objects.requireNonNull(p);
  58         return (T t) -> test(t) && p.test(t);
  59     }
  60 
  61     /**
  62      * Returns a predicate which negates the result of this predicate.
  63      *
  64      * @return a new predicate who's result is always the opposite of this
  65      * predicate.
  66      */
  67     public default Predicate<T> negate() {
  68         return (T t) -> !test(t);
  69     }
  70 
  71     /**
  72      * Returns a predicate which evaluates to {@code true} if either this
  73      * predicate or the provided predicate evaluates to {@code true}. If this
  74      * predicate returns {@code true} then the remaining predicate is not
  75      * evaluated.
  76      *
  77      * @return a new predicate which returns {@code true} if either predicate
  78      * returns {@code true}.
  79      */
  80     public default Predicate<T> or(Predicate<? super T> p) {
  81         Objects.requireNonNull(p);
  82         return (T t) -> test(t) || p.test(t);
  83     }
  84 
  85     /**
  86      * Returns a predicate that evaluates to {@code true} if all or none of the
  87      * component predicates evaluate to {@code true}.
  88      *
  89      * @return  a predicate that evaluates to {@code true} if all or none of the
  90      * component predicates evaluate to {@code true}
  91      */
  92     public default Predicate<T> xor(Predicate<? super T> p) {
  93         Objects.requireNonNull(p);
  94         return (T t) -> test(t) ^ p.test(t);
  95     }
  96 }