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 * Apply a function to the input arguments, yielding an appropriate result. This 31 * is the two-arity specialization of {@link Function}. A function may 32 * variously provide a mapping between types, object instances or keys and 33 * values or any other form of transformation upon the input. 34 * 35 * @param <T> the type of the first argument to the {@code apply} operation 36 * @param <U> the type of the second argument to the {@code apply} operation 37 * @param <R> the type of results returned by the {@code apply} operation 38 * 39 * @see Function 40 * @since 1.8 41 */ 42 @FunctionalInterface 43 public interface BiFunction<T, U, R> { 44 45 /** 46 * Compute the result of applying the function to the input arguments 47 * 48 * @param t an input object 49 * @param u an input object 50 * @return the function result 51 */ 52 R apply(T t, U u); 53 54 /** 55 * Returns a new function which applies this function followed by the 56 * provided function. If either function throws an exception, it is relayed 57 * to the caller. 58 * 59 * @param <V> Type of output objects to the combined function. May be the 60 * same type as {@code <T>}, {@code <U>} or {@code <R>} 61 * @param after An additional function to be applied after this function is 62 * applied 63 * @return A function which performs this function followed by the provided 64 * function 65 * @throws NullPointerException if after is null 66 */ 67 default <V> BiFunction<T, U, V> andThen(Function<? super R, ? extends V> after) { 68 Objects.requireNonNull(after); 69 return (T t, U u) -> after.apply(apply(t, u)); 70 } 71 }