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 an operation that accepts a single input argument and returns no

    31  * result. Unlike most other functional interfaces, {@code Consumer} is expected

    32  * to operate via side-effects.

    33  *

    34  * <p>This is a <a href="package-summary.html">functional interface</a>

    35  * whose functional method is {@link #accept(Object)}.

    36  *

    37  * @param <T> the type of the input to the operation

    38  *

    39  * @since 1.8

    40  */

    41 @FunctionalInterface

    42 public interface Consumer<T> {

    43 

    44     /**

    45      * Performs this operation on the given argument.

    46      *

    47      * @param t the input argument

    48      */

    49     void accept(T t);

    50 

    51     /**

    52      * Returns a composed {@code Consumer} that performs, in sequence, this

    53      * operation followed by the {@code after} operation. If performing either

    54      * operation throws an exception, it is relayed to the caller of the

    55      * composed operation.  If performing this operation throws an exception,

    56      * the {@code after} operation will not be performed.

    57      *

    58      * @param after the operation to perform after this operation

    59      * @return a composed {@code Consumer} that performs in sequence this

    60      * operation followed by the {@code after} operation

    61      * @throws NullPointerException if {@code after} is null

    62      */

    63     default Consumer<T> andThen(Consumer<? super T> after) {

    64         Objects.requireNonNull(after);

    65         return (T t) -> { accept(t); after.accept(t); };

    66     }

    67 }