1 /*
   2  * Copyright (c) 2012, 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  * An operation which accepts two input arguments and returns no result. This is
  31  * the two-arity specialization of {@link Consumer}. Unlike most other
  32  * functional interfaces, {@code BiConsumer} is expected to operate via
  33  * side-effects.
  34  *
  35  * @param <T> the type of the first argument to the {@code accept} operation
  36  * @param <U> the type of the second argument to the {@code accept} operation
  37  *
  38  * @see Consumer
  39  * @since 1.8
  40  */
  41 @FunctionalInterface
  42 public interface BiConsumer<T, U> {
  43 
  44     /**
  45      * Performs operations upon the provided objects which may modify those
  46      * objects and/or external state.
  47      *
  48      * @param t an input object
  49      * @param u an input object
  50      */
  51     void accept(T t, U u);
  52 
  53     /**
  54      * Returns a BiConsumer which performs in sequence the {@code accept}
  55      * methods of multiple BiConsumers. This BiConsumer's {@code accept} method
  56      * is performed followed by the {@code accept} method of the specified
  57      * BiConsumer operation.
  58      *
  59      * @param other an additional BiConsumer which will be chained after this
  60      * BiConsumer
  61      * @return a BiConsumer which performs in sequence the {@code accept} method
  62      * of this BiConsumer and the {@code accept} method of the specified
  63      * BiConsumer operation
  64      * @throws NullPointerException if other is null
  65      */
  66     default BiConsumer<T, U> chain(BiConsumer<? super T, ? super U> other) {
  67         Objects.requireNonNull(other);
  68 
  69         return (l, r) -> {
  70             accept(l, r);
  71             other.accept(l, r);
  72         };
  73     }
  74 }