Consumer.java revision e053d5ee5eea301559822c98e69874344c971502
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 */ 25package java.util.function; 26 27import 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 * @hide 1.8 41 */ 42@FunctionalInterface 43public interface Consumer<T> { 44 45 /** 46 * Performs this operation on the given argument. 47 * 48 * @param t the input argument 49 */ 50 void accept(T t); 51 52 /** 53 * Returns a composed {@code Consumer} that performs, in sequence, this 54 * operation followed by the {@code after} operation. If performing either 55 * operation throws an exception, it is relayed to the caller of the 56 * composed operation. If performing this operation throws an exception, 57 * the {@code after} operation will not be performed. 58 * 59 * @param after the operation to perform after this operation 60 * @return a composed {@code Consumer} that performs in sequence this 61 * operation followed by the {@code after} operation 62 * @throws NullPointerException if {@code after} is null 63 */ 64 default Consumer<T> andThen(Consumer<? super T> after) { 65 Objects.requireNonNull(after); 66 return (T t) -> { accept(t); after.accept(t); }; 67 } 68} 69