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 a function that accepts two arguments and produces a result. 31 * This is the two-arity specialization of {@link Function}. 32 * 33 * <p>This is a <a href="package-summary.html">functional interface</a> 34 * whose functional method is {@link #apply(Object, Object)}. 35 * 36 * @param <T> the type of the first argument to the function 37 * @param <U> the type of the second argument to the function 38 * @param <R> the type of the result of the function 39 * 40 * @see Function 41 * @since 1.8 42 */ 43 @FunctionalInterface 44 public interface BiFunction<T, U, R> { 45 46 /** 47 * Applies this function to the given arguments. 48 * 49 * @param t the first function argument 50 * @param u the second function argument 51 * @return the function result 52 */ apply(T t, U u)53 R apply(T t, U u); 54 55 /** 56 * Returns a composed function that first applies this function to 57 * its input, and then applies the {@code after} function to the result. 58 * If evaluation of either function throws an exception, it is relayed to 59 * the caller of the composed function. 60 * 61 * @param <V> the type of output of the {@code after} function, and of the 62 * composed function 63 * @param after the function to apply after this function is applied 64 * @return a composed function that first applies this function and then 65 * applies the {@code after} function 66 * @throws NullPointerException if after is null 67 */ andThen(Function<? super R, ? extends V> after)68 default <V> BiFunction<T, U, V> andThen(Function<? super R, ? extends V> after) { 69 Objects.requireNonNull(after); 70 return (T t, U u) -> after.apply(apply(t, u)); 71 } 72 } 73