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.juneau.commons.function; 018 019import static org.apache.juneau.commons.utils.Shorts.*; 020 021 022/** 023 * A functional interface representing an operation that accepts two arguments and returns no result. 024 * 025 * <p> 026 * This interface extends the standard Java {@link java.util.function.Consumer} pattern to support 027 * two-argument consumers. It's useful when you need to pass operations with two parameters to methods 028 * that expect functional interfaces, such as in iteration, builders, or callback patterns. 029 * 030 * <h5 class='section'>Features:</h5> 031 * <ul class='spaced-list'> 032 * <li>Functional interface - can be used with lambda expressions and method references 033 * <li>Composition support - provides {@link #andThen(Consumer2)} for operation chaining 034 * <li>Side-effect operations - designed for operations that perform side effects rather than return values 035 * </ul> 036 * 037 * <h5 class='section'>Use Cases:</h5> 038 * <ul class='spaced-list'> 039 * <li>Two-argument operations in iteration patterns 040 * <li>Builder methods that accept two-parameter operations 041 * <li>Callback patterns with two parameters 042 * <li>Event handlers that process two values 043 * </ul> 044 * 045 * <h5 class='section'>Usage:</h5> 046 * <p class='bjava'> 047 * <jc>// Lambda expression</jc> 048 * Consumer2<String,Integer> <jv>printer</jv> = (<jv>name</jv>, <jv>age</jv>) -> 049 * System.<jsf>out</jsf>.println(<jv>name</jv> + <js>" is "</js> + <jv>age</jv> + <js>" years old"</js>); 050 * <jv>printer</jv>.apply(<js>"Alice"</js>, 30); <jc>// Prints "Alice is 30 years old"</jc> 051 * 052 * <jc>// Method reference</jc> 053 * Map<String,Integer> <jv>map</jv> = <jk>new</jk> HashMap<>(); 054 * Consumer2<String,Integer> <jv>putter</jv> = <jv>map</jv>::put; 055 * <jv>putter</jv>.apply(<js>"key"</js>, 42); 056 * 057 * <jc>// Operation composition</jc> 058 * Consumer2<String,Integer> <jv>log</jv> = (<jv>s</jv>, <jv>i</jv>) -> <jsm>logger</jsm>.info(<jv>s</jv> + <js>": "</js> + <jv>i</jv>); 059 * Consumer2<String,Integer> <jv>store</jv> = (<jv>s</jv>, <jv>i</jv>) -> <jv>cache</jv>.put(<jv>s</jv>, <jv>i</jv>); 060 * Consumer2<String,Integer> <jv>logAndStore</jv> = <jv>log</jv>.andThen(<jv>store</jv>); 061 * <jv>logAndStore</jv>.apply(<js>"data"</js>, 100); <jc>// Logs and stores</jc> 062 * </p> 063 * 064 * <h5 class='section'>See Also:</h5><ul> 065 * <li class='jc'>{@link Consumer3} - Three-argument consumer 066 * <li class='jc'>{@link Consumer4} - Four-argument consumer 067 * <li class='jc'>{@link Consumer5} - Five-argument consumer 068 * <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/JuneauCommons">juneau-commons</a> 069 * </ul> 070 * 071 * @param <A> The type of the first argument to the operation. 072 * @param <B> The type of the second argument to the operation. 073 */ 074@FunctionalInterface 075@SuppressWarnings({ 076 "java:S1192" // Duplicated literals (argument/property names) read more clearly inline than as constants 077}) 078public interface Consumer2<A,B> { 079 080 /** 081 * Returns a composed {@link Consumer2} that performs, in sequence, this operation followed by the {@code after} operation. 082 * 083 * <p> 084 * This method enables operation composition, allowing you to chain multiple operations together. 085 * If performing either operation throws an exception, it is relayed to the caller of the composed operation. 086 * If performing this operation throws an exception, the {@code after} operation will not be performed. 087 * 088 * <h5 class='section'>Example:</h5> 089 * <p class='bjava'> 090 * Consumer2<String,Integer> <jv>validate</jv> = (<jv>s</jv>, <jv>i</jv>) -> { 091 * <jk>if</jk> (<jv>i</jv> < 0) <jk>throw new</jk> IllegalArgumentException(); 092 * }; 093 * Consumer2<String,Integer> <jv>process</jv> = (<jv>s</jv>, <jv>i</jv>) -> <jsm>process</jsm>(<jv>s</jv>, <jv>i</jv>); 094 * Consumer2<String,Integer> <jv>validateAndProcess</jv> = <jv>validate</jv>.andThen(<jv>process</jv>); 095 * <jv>validateAndProcess</jv>.apply(<js>"data"</js>, 42); <jc>// Validates then processes</jc> 096 * </p> 097 * 098 * @param after The operation to perform after this operation. Must not be <jk>null</jk>. 099 * @return A composed {@link Consumer2} that performs in sequence this operation followed by the {@code after} operation. 100 * @throws NullPointerException if {@code after} is <jk>null</jk>. 101 */ 102 default Consumer2<A,B> andThen(Consumer2<? super A,? super B> after) { 103 reqnn("after", after); 104 return (A a, B b) -> { 105 apply(a, b); 106 after.apply(a, b); 107 }; 108 } 109 110 /** 111 * Performs this operation on the given arguments. 112 * 113 * <h5 class='section'>Example:</h5> 114 * <p class='bjava'> 115 * Consumer2<String,Integer> <jv>handler</jv> = (<jv>key</jv>, <jv>value</jv>) -> { 116 * <jv>map</jv>.put(<jv>key</jv>, <jv>value</jv>); 117 * <jv>cache</jv>.invalidate(<jv>key</jv>); 118 * }; 119 * <jv>handler</jv>.apply(<js>"user"</js>, 12345); 120 * </p> 121 * 122 * @param a The first operation argument. 123 * @param b The second operation argument. 124 */ 125 void apply(A a, B b); 126}