Consumer.java revision 4b92e5b21380a5344e5808b17ddffb994f855288 
1/*
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24 */
25package java.util.function;
26
27import java.util.Objects;
28
29/**
30 * Represents an operation that accepts a single input argument and returns no
31 * result. Unlike most other functional interfaces, {@code Consumer} is expected
32 * to operate via side-effects.
33 *
34 * <p>This is a <a href="package-summary.html">functional interface</a>
35 * whose functional method is {@link #accept(Object)}.
36 *
37 * @param <T> the type of the input to the operation
38 *
39 * @since 1.8
40 */
41@FunctionalInterface
42public interface Consumer<T> {
43
44    /**
45     * Performs this operation on the given argument.
46     *
47     * @param t the input argument
48     */
49    void accept(T t);
50
51    /**
52     * Returns a composed {@code Consumer} that performs, in sequence, this
53     * operation followed by the {@code after} operation. If performing either
54     * operation throws an exception, it is relayed to the caller of the
55     * composed operation.  If performing this operation throws an exception,
56     * the {@code after} operation will not be performed.
57     *
58     * @param after the operation to perform after this operation
59     * @return a composed {@code Consumer} that performs in sequence this
60     * operation followed by the {@code after} operation
61     * @throws NullPointerException if {@code after} is null
62     */
63    default Consumer<T> andThen(Consumer<? super T> after) {
64        Objects.requireNonNull(after);
65        return (T t) -> { accept(t); after.accept(t); };
66    }
67}
68