UnaryOperator.java revision 2278037aa1653a32014df55f325879b4fe75fc27 
1/*
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25package java.util.function;
26
27/**
28 * Represents an operation on a single operand that produces a result of the
29 * same type as its operand.  This is a specialization of {@code Function} for
30 * the case where the operand and result are of the same type.
31 *
32 * <p>This is a <a href="package-summary.html">functional interface</a>
33 * whose functional method is {@link #apply(Object)}.
34 *
35 * @param <T> the type of the operand and result of the operator
36 *
37 * @see Function
38 * @since 1.8
39 */
40@FunctionalInterface
41public interface UnaryOperator<T> extends Function<T, T> {
42
43    /**
44     * Returns a unary operator that always returns its input argument.
45     *
46     * @param <T> the type of the input and output of the operator
47     * @return a unary operator that always returns its input argument
48     */
49    static <T> UnaryOperator<T> identity() {
50        return t -> t;
51    }
52}
53