1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.lang3.function;
19
20 import java.util.Objects;
21 import java.util.function.Consumer;
22 import java.util.function.Function;
23
24 /**
25 * A functional interface like {@link Consumer} that declares a {@link Throwable}.
26 *
27 * <p>
28 * This is a functional interface whose functional method is {@link #accept(Object)}.
29 * </p>
30 *
31 * @param <T> The type of the argument the consumer accepts.
32 * @param <E> The thrown exception type.
33 * @since 3.11
34 */
35 @FunctionalInterface
36 public interface FailableConsumer<T, E extends Throwable> {
37
38 /** NOP singleton */
39 @SuppressWarnings("rawtypes")
40 FailableConsumer NOP = Function.identity()::apply;
41
42 /**
43 * Applies the given {@link FailableConsumer} action to the object if the consumer is not {@code null}. Otherwise, does nothing.
44 *
45 * @param consumer The consumer to consume.
46 * @param object The object to be consumed.
47 * @param <T> the type of the argument the consumer accepts.
48 * @param <E> The thrown exception type.
49 * @throws E Thrown when the consumer fails.
50 * @since 3.21.0
51 */
52 static <T, E extends Throwable> void accept(final FailableConsumer<T, E> consumer, final T object) throws E {
53 if (consumer != null) {
54 consumer.accept(object);
55 }
56 }
57
58 /**
59 * Gets the NOP singleton.
60 *
61 * @param <T> The type of the argument the consumer accepts.
62 * @param <E> The thrown exception type.
63 * @return The NOP singleton.
64 */
65 @SuppressWarnings("unchecked")
66 static <T, E extends Throwable> FailableConsumer<T, E> nop() {
67 return NOP;
68 }
69
70 /**
71 * Accepts the given arguments.
72 *
73 * @param object The parameter for the consumable to accept
74 * @throws E Thrown when the consumer fails.
75 */
76 void accept(T object) throws E;
77
78 /**
79 * Returns a composed {@link Consumer} like {@link Consumer#andThen(Consumer)}.
80 *
81 * @param after The operation to perform after this operation
82 * @return A composed {@link Consumer} like {@link Consumer#andThen(Consumer)}.
83 * @throws NullPointerException Thrown when {@code after} is null.
84 */
85 default FailableConsumer<T, E> andThen(final FailableConsumer<? super T, E> after) {
86 Objects.requireNonNull(after, "after");
87 return (final T t) -> {
88 accept(t);
89 after.accept(t);
90 };
91 }
92 }