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25 package java.util.function;
26 
27 import 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
42 public interface Consumer<T> {
43 
44     /**
45      * Performs this operation on the given argument.
46      *
47      * @param t the input argument
48      */
accept(T t)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      */
andThen(Consumer<? super T> after)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