BiFunction.java revision e053d5ee5eea301559822c98e69874344c971502 
1/*
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25package java.util.function;
26
27import 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 * @hide 1.8
43 */
44@FunctionalInterface
45public interface BiFunction<T, U, R> {
46
47    /**
48     * Applies this function to the given arguments.
49     *
50     * @param t the first function argument
51     * @param u the second function argument
52     * @return the function result
53     */
54    R apply(T t, U u);
55
56    /**
57     * Returns a composed function that first applies this function to
58     * its input, and then applies the {@code after} function to the result.
59     * If evaluation of either function throws an exception, it is relayed to
60     * the caller of the composed function.
61     *
62     * @param <V> the type of output of the {@code after} function, and of the
63     *           composed function
64     * @param after the function to apply after this function is applied
65     * @return a composed function that first applies this function and then
66     * applies the {@code after} function
67     * @throws NullPointerException if after is null
68     */
69    default <V> BiFunction<T, U, V> andThen(Function<? super R, ? extends V> after) {
70        Objects.requireNonNull(after);
71        return (T t, U u) -> after.apply(apply(t, u));
72    }
73}
74