| /* |
| * 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; |
| |
| import java.util.function.LongConsumer; |
| import java.util.function.LongSupplier; |
| import java.util.function.Supplier; |
| |
| // Android-changed: removed ValueBased paragraph. |
| /** |
| * A container object which may or may not contain a {@code long} value. |
| * If a value is present, {@code isPresent()} will return {@code true} and |
| * {@code getAsLong()} will return the value. |
| * |
| * <p>Additional methods that depend on the presence or absence of a contained |
| * value are provided, such as {@link #orElse(long) orElse()} |
| * (return a default value if value not present) and |
| * {@link #ifPresent(java.util.function.LongConsumer) ifPresent()} (execute a block |
| * of code if the value is present). |
| * |
| * @since 1.8 |
| */ |
| public final class OptionalLong { |
| /** |
| * Common instance for {@code empty()}. |
| */ |
| private static final OptionalLong EMPTY = new OptionalLong(); |
| |
| /** |
| * If true then the value is present, otherwise indicates no value is present |
| */ |
| private final boolean isPresent; |
| private final long value; |
| |
| /** |
| * Construct an empty instance. |
| * |
| * @implNote generally only one empty instance, {@link OptionalLong#EMPTY}, |
| * should exist per VM. |
| */ |
| private OptionalLong() { |
| this.isPresent = false; |
| this.value = 0; |
| } |
| |
| /** |
| * Returns an empty {@code OptionalLong} instance. No value is present for this |
| * OptionalLong. |
| * |
| * @apiNote Though it may be tempting to do so, avoid testing if an object |
| * is empty by comparing with {@code ==} against instances returned by |
| * {@code Option.empty()}. There is no guarantee that it is a singleton. |
| * Instead, use {@link #isPresent()}. |
| * |
| * @return an empty {@code OptionalLong}. |
| */ |
| public static OptionalLong empty() { |
| return EMPTY; |
| } |
| |
| /** |
| * Construct an instance with the value present. |
| * |
| * @param value the long value to be present |
| */ |
| private OptionalLong(long value) { |
| this.isPresent = true; |
| this.value = value; |
| } |
| |
| /** |
| * Return an {@code OptionalLong} with the specified value present. |
| * |
| * @param value the value to be present |
| * @return an {@code OptionalLong} with the value present |
| */ |
| public static OptionalLong of(long value) { |
| return new OptionalLong(value); |
| } |
| |
| /** |
| * If a value is present in this {@code OptionalLong}, returns the value, |
| * otherwise throws {@code NoSuchElementException}. |
| * |
| * @return the value held by this {@code OptionalLong} |
| * @throws NoSuchElementException if there is no value present |
| * |
| * @see OptionalLong#isPresent() |
| */ |
| public long getAsLong() { |
| if (!isPresent) { |
| throw new NoSuchElementException("No value present"); |
| } |
| return value; |
| } |
| |
| /** |
| * Return {@code true} if there is a value present, otherwise {@code false}. |
| * |
| * @return {@code true} if there is a value present, otherwise {@code false} |
| */ |
| public boolean isPresent() { |
| return isPresent; |
| } |
| |
| /** |
| * Have the specified consumer accept the value if a value is present, |
| * otherwise do nothing. |
| * |
| * @param consumer block to be executed if a value is present |
| * @throws NullPointerException if value is present and {@code consumer} is |
| * null |
| */ |
| public void ifPresent(LongConsumer consumer) { |
| if (isPresent) |
| consumer.accept(value); |
| } |
| |
| /** |
| * Return the value if present, otherwise return {@code other}. |
| * |
| * @param other the value to be returned if there is no value present |
| * @return the value, if present, otherwise {@code other} |
| */ |
| public long orElse(long other) { |
| return isPresent ? value : other; |
| } |
| |
| /** |
| * Return the value if present, otherwise invoke {@code other} and return |
| * the result of that invocation. |
| * |
| * @param other a {@code LongSupplier} whose result is returned if no value |
| * is present |
| * @return the value if present otherwise the result of {@code other.getAsLong()} |
| * @throws NullPointerException if value is not present and {@code other} is |
| * null |
| */ |
| public long orElseGet(LongSupplier other) { |
| return isPresent ? value : other.getAsLong(); |
| } |
| |
| /** |
| * Return the contained value, if present, otherwise throw an exception |
| * to be created by the provided supplier. |
| * |
| * @apiNote A method reference to the exception constructor with an empty |
| * argument list can be used as the supplier. For example, |
| * {@code IllegalStateException::new} |
| * |
| * @param <X> Type of the exception to be thrown |
| * @param exceptionSupplier The supplier which will return the exception to |
| * be thrown |
| * @return the present value |
| * @throws X if there is no value present |
| * @throws NullPointerException if no value is present and |
| * {@code exceptionSupplier} is null |
| */ |
| public<X extends Throwable> long orElseThrow(Supplier<X> exceptionSupplier) throws X { |
| if (isPresent) { |
| return value; |
| } else { |
| throw exceptionSupplier.get(); |
| } |
| } |
| |
| /** |
| * Indicates whether some other object is "equal to" this OptionalLong. The |
| * other object is considered equal if: |
| * <ul> |
| * <li>it is also an {@code OptionalLong} and; |
| * <li>both instances have no value present or; |
| * <li>the present values are "equal to" each other via {@code ==}. |
| * </ul> |
| * |
| * @param obj an object to be tested for equality |
| * @return {code true} if the other object is "equal to" this object |
| * otherwise {@code false} |
| */ |
| @Override |
| public boolean equals(Object obj) { |
| if (this == obj) { |
| return true; |
| } |
| |
| if (!(obj instanceof OptionalLong)) { |
| return false; |
| } |
| |
| OptionalLong other = (OptionalLong) obj; |
| return (isPresent && other.isPresent) |
| ? value == other.value |
| : isPresent == other.isPresent; |
| } |
| |
| /** |
| * Returns the hash code value of the present value, if any, or 0 (zero) if |
| * no value is present. |
| * |
| * @return hash code value of the present value or 0 if no value is present |
| */ |
| @Override |
| public int hashCode() { |
| return isPresent ? Long.hashCode(value) : 0; |
| } |
| |
| /** |
| * {@inheritDoc} |
| * |
| * Returns a non-empty string representation of this object suitable for |
| * debugging. The exact presentation format is unspecified and may vary |
| * between implementations and versions. |
| * |
| * @implSpec If a value is present the result must include its string |
| * representation in the result. Empty and present instances must be |
| * unambiguously differentiable. |
| * |
| * @return the string representation of this instance |
| */ |
| @Override |
| public String toString() { |
| return isPresent |
| ? String.format("OptionalLong[%s]", value) |
| : "OptionalLong.empty"; |
| } |
| } |