Java example source code file (LongUnaryOperator.java)

This example Java source code file (LongUnaryOperator.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

functionalinterface, longunaryoperator, util

The LongUnaryOperator.java Java example source code

/*
 * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package java.util.function;

import java.util.Objects;

/**
 * Represents an operation on a single {@code long}-valued operand that produces
 * a {@code long}-valued result.  This is the primitive type specialization of
 * {@link UnaryOperator} for {@code long}.
 *
 * <p>This is a functional interface
 * whose functional method is {@link #applyAsLong(long)}.
 *
 * @see UnaryOperator
 * @since 1.8
 */
@FunctionalInterface
public interface LongUnaryOperator {

    /**
     * Applies this operator to the given operand.
     *
     * @param operand the operand
     * @return the operator result
     */
    long applyAsLong(long operand);

    /**
     * Returns a composed operator that first applies the {@code before}
     * operator to its input, and then applies this operator to the result.
     * If evaluation of either operator throws an exception, it is relayed to
     * the caller of the composed operator.
     *
     * @param before the operator to apply before this operator is applied
     * @return a composed operator that first applies the {@code before}
     * operator and then applies this operator
     * @throws NullPointerException if before is null
     *
     * @see #andThen(LongUnaryOperator)
     */
    default LongUnaryOperator compose(LongUnaryOperator before) {
        Objects.requireNonNull(before);
        return (long v) -> applyAsLong(before.applyAsLong(v));
    }

    /**
     * Returns a composed operator that first applies this operator to
     * its input, and then applies the {@code after} operator to the result.
     * If evaluation of either operator throws an exception, it is relayed to
     * the caller of the composed operator.
     *
     * @param after the operator to apply after this operator is applied
     * @return a composed operator that first applies this operator and then
     * applies the {@code after} operator
     * @throws NullPointerException if after is null
     *
     * @see #compose(LongUnaryOperator)
     */
    default LongUnaryOperator andThen(LongUnaryOperator after) {
        Objects.requireNonNull(after);
        return (long t) -> after.applyAsLong(applyAsLong(t));
    }

    /**
     * Returns a unary operator that always returns its input argument.
     *
     * @return a unary operator that always returns its input argument
     */
    static LongUnaryOperator identity() {
        return t -> t;
    }
}