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 }
|
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 */
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 */
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 }
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