content: /*
   * 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(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";
      }
  }
  