/*
 
* Copyright (c) 2012, 2015, 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.
 
*/

/*
 
* This file is available under and governed by the GNU General Public
 
* License version 2 only, as published by the Free Software Foundation.
 
* However, the following notice accompanied the original version of this
 
* file:
 
*
 
* Copyright (c) 2007-2012, Stephen Colebourne & Michael Nascimento Santos
 
*
 
* All rights reserved.
 
*
 
* Redistribution and use in source and binary forms, with or without
 
* modification, are permitted provided that the following conditions are met:
 
*
 
*
  
* Redistributions of source code must retain the above copyright notice,
 
*
    
this list of conditions and the following disclaimer.
 
*
 
*
  
* Redistributions in binary form must reproduce the above copyright notice,
 
*
    
this list of conditions and the following disclaimer in the documentation
 
*
    
and/or other materials provided with the distribution.
 
*
 
*
  
* Neither the name of JSR-310 nor the names of its contributors
 
*
    
may be used to endorse or promote products derived from this software
 
*
    
without specific prior written permission.
 
*
 
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
*/

package java.time;

import static java.time.LocalTime.NANOS_PER_SECOND;
import static java.time.LocalTime.SECONDS_PER_DAY;
import static java.time.LocalTime.SECONDS_PER_HOUR;
import static java.time.LocalTime.SECONDS_PER_MINUTE;
import static java.time.temporal.ChronoField.INSTANT_SECONDS;
import static java.time.temporal.ChronoField.MICRO_OF_SECOND;
import static java.time.temporal.ChronoField.MILLI_OF_SECOND;
import static java.time.temporal.ChronoField.NANO_OF_SECOND;
import static java.time.temporal.ChronoUnit.DAYS;
import static java.time.temporal.ChronoUnit.NANOS;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeParseException;
import java.time.temporal.ChronoField;
import java.time.temporal.ChronoUnit;
import java.time.temporal.Temporal;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.TemporalAdjuster;
import java.time.temporal.TemporalAmount;
import java.time.temporal.TemporalField;
import java.time.temporal.TemporalQueries;
import java.time.temporal.TemporalQuery;
import java.time.temporal.TemporalUnit;
import java.time.temporal.UnsupportedTemporalTypeException;
import java.time.temporal.ValueRange;
import java.util.Objects;

/**
 
* An instantaneous point on the time-line.
 
* <p>
 
* This class models a single instantaneous point on the time-line.
 
* This might be used to record event time-stamps in the application.
 
* <p>
 
* The range of an instant requires the storage of a number larger than a {@code long}.
 
* To achieve this, the class stores a {@code long} representing epoch-seconds and an
 
* {@code int} representing nanosecond-of-second, which will always be between 0 and 999,999,999.
 
* The epoch-seconds are measured from the standard Java epoch of {@code 1970-01-01T00:00:00Z}
 
* where instants after the epoch have positive values, and earlier instants have negative values.
 
* For both the epoch-second and nanosecond parts, a larger value is always later on the time-line
 
* than a smaller value.
 
*
 
* <h3>Time-scale</h3>
 
* <p>
 
* The length of the solar day is the standard way that humans measure time.
 
* This has traditionally been subdivided into 24 hours of 60 minutes of 60 seconds,
 
* forming a 86400 second day.
 
* <p>
 
* Modern timekeeping is based on atomic clocks which precisely define an SI second
 
* relative to the transitions of a Caesium atom. The length of an SI second was defined
 
* to be very close to the 86400th fraction of a day.
 
* <p>
 
* Unfortunately, as the Earth rotates the length of the day varies.
 
* In addition, over time the average length of the day is getting longer as the Earth slows.
 
* As a result, the length of a solar day in 2012 is slightly longer than 86400 SI seconds.
 
* The actual length of any given day and the amount by which the Earth is slowing
 
* are not predictable and can only be determined by measurement.
 
* The UT1 time-scale captures the accurate length of day, but is only available some
 
* time after the day has completed.
 
* <p>
 
* The UTC time-scale is a standard approach to bundle up all the additional fractions
 
* of a second from UT1 into whole seconds, known as <i>leap-seconds</i>.
 
* A leap-second may be added or removed depending on the Earth's rotational changes.
 
* As such, UTC permits a day to have 86399 SI seconds or 86401 SI seconds where
 
* necessary in order to keep the day aligned with the Sun.
 
* <p>
 
* The modern UTC time-scale was introduced in 1972, introducing the concept of whole leap-seconds.
 
* Between 1958 and 1972, the definition of UTC was complex, with minor sub-second leaps and
 
* alterations to the length of the notional second. As of 2012, discussions are underway
 
* to change the definition of UTC again, with the potential to remove leap seconds or
 
* introduce other changes.
 
* <p>
 
* Given the complexity of accurate timekeeping described above, this Java API defines
 
* its own time-scale, the <i>Java Time-Scale</i>.
 
* <p>
 
* The Java Time-Scale divides each calendar day into exactly 86400
 
* subdivisions, known as seconds.
  
These seconds may differ from the
 
* SI second.
  
It closely matches the de facto international civil time
 
* scale, the definition of which changes from time to time.
 
* <p>
 
* The Java Time-Scale has slightly different definitions for different
 
* segments of the time-line, each based on the consensus international
 
* time scale that is used as the basis for civil time. Whenever the
 
* internationally-agreed time scale is modified or replaced, a new
 
* segment of the Java Time-Scale must be defined for it.
  
Each segment
 
* must meet these requirements:
 
* <ul>
 
* <li>the Java Time-Scale shall closely match the underlying international
 
*
  
civil time scale;</li>
 
* <li>the Java Time-Scale shall exactly match the international civil
 
*
  
time scale at noon each day;</li>
 
* <li>the Java Time-Scale shall have a precisely-defined relationship to
 
*
  
the international civil time scale.</li>
 
* </ul>
 
* There are currently, as of 2013, two segments in the Java time-scale.
 
* <p>
 
* For the segment from 1972-11-03 (exact boundary discussed below) until
 
* further notice, the consensus international time scale is UTC (with
 
* leap seconds).
  
In this segment, the Java Time-Scale is identical to
 
*<a href="http://www.cl.cam.ac.uk/~mgk25/time/utc-sls/">UTC-SLS</a>.
 
* This is identical to UTC on days that do not have a leap second.
 
* On days that do have a leap second, the leap second is spread equally
 
* over the last 1000 seconds of the day, maintaining the appearance of
 
* exactly 86400 seconds per day.
 
* <p>
 
* For the segment prior to 1972-11-03, extending back arbitrarily far,
 
* the consensus international time scale is defined to be UT1, applied
 
* proleptically, which is equivalent to the (mean) solar time on the
 
* prime meridian (Greenwich). In this segment, the Java Time-Scale is
 
* identical to the consensus international time scale. The exact
 
* boundary between the two segments is the instant where UT1 = UTC
 
* between 1972-11-03T00:00 and 1972-11-04T12:00.
 
* <p>
 
* Implementations of the Java time-scale using the JSR-310 API are not
 
* required to provide any clock that is sub-second accurate, or that
 
* progresses monotonically or smoothly. Implementations are therefore
 
* not required to actually perform the UTC-SLS slew or to otherwise be
 
* aware of leap seconds. JSR-310 does, however, require that
 
* implementations must document the approach they use when defining a
 
* clock representing the current instant.
 
* See {@link Clock} for details on the available clocks.
 
* <p>
 
* The Java time-scale is used for all date-time classes.
 
* This includes {@code Instant}, {@code LocalDate}, {@code LocalTime}, {@code OffsetDateTime},
 
* {@code ZonedDateTime} and {@code Duration}.
 
*
 
* <p>
 
* This is a<a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
 
* class; use of identity-sensitive operations (including reference equality
 
* ({@code ==}), identity hash code, or synchronization) on instances of
 
* {@code Instant} may have unpredictable results and should be avoided.
 
* The {@code equals} method should be used for comparisons.
 
*
 
* @implSpec
 
* This class is immutable and thread-safe.
 
*
 
* @since 1.8
 
*/

public final class Instant
        
implements Temporal, TemporalAdjuster, Comparable<Instant>, Serializable {

    
/**
     
* Constant for the 1970-01-01T00:00:00Z epoch instant.
     
*/
    
public static final Instant EPOCH = new Instant(0, 0);
    
/**
     
* The minimum supported epoch second.
     
*/
    
private static final long MIN_SECOND = -31557014167219200L;
    
/**
     
* The maximum supported epoch second.
     
*/
    
private static final long MAX_SECOND = 31556889864403199L;
    
/**
     
* The minimum supported {@code Instant}, '-1000000000-01-01T00:00Z'.
     
* This could be used by an application as a "far past" instant.
     
* <p>
     
* This is one year earlier than the minimum {@code LocalDateTime}.
     
* This provides sufficient values to handle the range of {@code ZoneOffset}
     
* which affect the instant in addition to the local date-time.
     
* The value is also chosen such that the value of the year fits in
     
* an {@code int}.
     
*/

    
public static final Instant MIN = Instant.ofEpochSecond(MIN_SECOND, 0);
    
/**
     
* The maximum supported {@code Instant}, '1000000000-12-31T23:59:59.999999999Z'.
     
* This could be used by an application as a "far future" instant.
     
* <p>
     
* This is one year later than the maximum {@code LocalDateTime}.
     
* This provides sufficient values to handle the range of {@code ZoneOffset}
     
* which affect the instant in addition to the local date-time.
     
* The value is also chosen such that the value of the year fits in
     
* an {@code int}.
     
*/

    
public static final Instant MAX = Instant.ofEpochSecond(MAX_SECOND, 999_999_999);

    
/**
     
* Serialization version.
     
*/
    
private static final long serialVersionUID = -665713676816604388L;

    
/**
     
* The number of seconds from the epoch of 1970-01-01T00:00:00Z.
     
*/
    
private final long seconds;
    
/**
     
* The number of nanoseconds, later along the time-line, from the seconds field.
     
* This is always positive, and never exceeds 999,999,999.
     
*/

    
private final int nanos;

    
//-----------------------------------------------------------------------
    
/**
     
* Obtains the current instant from the system clock.
     
* <p>
     
* This will query the {@link Clock#systemUTC() system UTC clock} to
     
* obtain the current instant.
     
* <p>
     
* Using this method will prevent the ability to use an alternate time-source for
     
* testing because the clock is effectively hard-coded.
     
*
     
* @return the current instant using the system clock, not null
     
*/

    
public static Instant now() {
        
return Clock.systemUTC().instant();
    
}

    
/**
     
* Obtains the current instant from the specified clock.
     
* <p>
     
* This will query the specified clock to obtain the current time.
     
* <p>
     
* Using this method allows the use of an alternate clock for testing.
     
* The alternate clock may be introduced using {@link Clock dependency injection}.
     
*
     
* @param clock
  
the clock to use, not null
     
* @return the current instant, not null
     
*/

    
public static Instant now(Clock clock) {
        
Objects.requireNonNull(clock, "clock");
        
return clock.instant();
    
}

    
//-----------------------------------------------------------------------
    
/**
     
* Obtains an instance of {@code Instant} using seconds from the
     
* epoch of 1970-01-01T00:00:00Z.
     
* <p>
     
* The nanosecond field is set to zero.
     
*
     
* @param epochSecond
  
the number of seconds from 1970-01-01T00:00:00Z
     
* @return an instant, not null
     
* @throws DateTimeException if the instant exceeds the maximum or minimum instant
     
*/

    
public static Instant ofEpochSecond(long epochSecond) {
        
return create(epochSecond, 0);
    
}

    
/**
     
* Obtains an instance of {@code Instant} using seconds from the
     
* epoch of 1970-01-01T00:00:00Z and nanosecond fraction of second.
     
* <p>
     
* This method allows an arbitrary number of nanoseconds to be passed in.
     
* The factory will alter the values of the second and nanosecond in order
     
* to ensure that the stored nanosecond is in the range 0 to 999,999,999.
     
* For example, the following will result in the exactly the same instant:
     
* <pre>
     
*
  
Instant.ofEpochSecond(3, 1);
     
*
  
Instant.ofEpochSecond(4, -999_999_999);
     
*
  
Instant.ofEpochSecond(2, 1000_000_001);
     
* </pre>
     
*
     
* @param epochSecond
  
the number of seconds from 1970-01-01T00:00:00Z
     
* @param nanoAdjustment
  
the nanosecond adjustment to the number of seconds, positive or negative
     
* @return an instant, not null
     
* @throws DateTimeException if the instant exceeds the maximum or minimum instant
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
public static Instant ofEpochSecond(long epochSecond, long nanoAdjustment) {
        
long secs = Math.addExact(epochSecond, Math.floorDiv(nanoAdjustment, NANOS_PER_SECOND));
        
int nos = (int)Math.floorMod(nanoAdjustment, NANOS_PER_SECOND);
        
return create(secs, nos);
    
}

    
/**
     
* Obtains an instance of {@code Instant} using milliseconds from the
     
* epoch of 1970-01-01T00:00:00Z.
     
* <p>
     
* The seconds and nanoseconds are extracted from the specified milliseconds.
     
*
     
* @param epochMilli
  
the number of milliseconds from 1970-01-01T00:00:00Z
     
* @return an instant, not null
     
* @throws DateTimeException if the instant exceeds the maximum or minimum instant
     
*/

    
public static Instant ofEpochMilli(long epochMilli) {
        
long secs = Math.floorDiv(epochMilli, 1000);
        
int mos = (int)Math.floorMod(epochMilli, 1000);
        
return create(secs, mos * 1000_000);
    
}

    
//-----------------------------------------------------------------------
    
/**
     
* Obtains an instance of {@code Instant} from a temporal object.
     
* <p>
     
* This obtains an instant based on the specified temporal.
     
* A {@code TemporalAccessor} represents an arbitrary set of date and time information,
     
* which this factory converts to an instance of {@code Instant}.
     
* <p>
     
* The conversion extracts the {@link ChronoField#INSTANT_SECONDS INSTANT_SECONDS}
     
* and {@link ChronoField#NANO_OF_SECOND NANO_OF_SECOND} fields.
     
* <p>
     
* This method matches the signature of the functional interface {@link TemporalQuery}
     
* allowing it to be used as a query via method reference, {@code Instant::from}.
     
*
     
* @param temporal
  
the temporal object to convert, not null
     
* @return the instant, not null
     
* @throws DateTimeException if unable to convert to an {@code Instant}
     
*/

    
public static Instant from(TemporalAccessor temporal) {
        
if (temporal instanceof Instant) {
            
return (Instant) temporal;
        
}
        
Objects.requireNonNull(temporal, "temporal");
        
try {
            
long instantSecs = temporal.getLong(INSTANT_SECONDS);
            
int nanoOfSecond = temporal.get(NANO_OF_SECOND);
            
return Instant.ofEpochSecond(instantSecs, nanoOfSecond);
        
} catch (DateTimeException ex) {
            
throw new DateTimeException("Unable to obtain Instant from TemporalAccessor: " +
                    
temporal + " of type " + temporal.getClass().getName(), ex);
        
}
    
}

    
//-----------------------------------------------------------------------
    
/**
     
* Obtains an instance of {@code Instant} from a text string such as
     
* {@code 2007-12-03T10:15:30.00Z}.
     
* <p>
     
* The string must represent a valid instant in UTC and is parsed using
     
* {@link DateTimeFormatter#ISO_INSTANT}.
     
*
     
* @param text
  
the text to parse, not null
     
* @return the parsed instant, not null
     
* @throws DateTimeParseException if the text cannot be parsed
     
*/

    
public static Instant parse(final CharSequence text) {
        
return DateTimeFormatter.ISO_INSTANT.parse(text, Instant::from);
    
}

    
//-----------------------------------------------------------------------
    
/**
     
* Obtains an instance of {@code Instant} using seconds and nanoseconds.
     
*
     
* @param seconds
  
the length of the duration in seconds
     
* @param nanoOfSecond
  
the nano-of-second, from 0 to 999,999,999
     
* @throws DateTimeException if the instant exceeds the maximum or minimum instant
     
*/

    
private static Instant create(long seconds, int nanoOfSecond) {
        
if ((seconds | nanoOfSecond) == 0) {
            
return EPOCH;
        
}
        
if (seconds < MIN_SECOND || seconds > MAX_SECOND) {
            
throw new DateTimeException("Instant exceeds minimum or maximum instant");
        
}
        
return new Instant(seconds, nanoOfSecond);
    
}

    
/**
     
* Constructs an instance of {@code Instant} using seconds from the epoch of
     
* 1970-01-01T00:00:00Z and nanosecond fraction of second.
     
*
     
* @param epochSecond
  
the number of seconds from 1970-01-01T00:00:00Z
     
* @param nanos
  
the nanoseconds within the second, must be positive
     
*/

    
private Instant(long epochSecond, int nanos) {
        
super();
        
this.seconds = epochSecond;
        
this.nanos = nanos;
    
}

    
//-----------------------------------------------------------------------
    
/**
     
* Checks if the specified field is supported.
     
* <p>
     
* This checks if this instant can be queried for the specified field.
     
* If false, then calling the {@link #range(TemporalField) range},
     
* {@link #get(TemporalField) get} and {@link #with(TemporalField, long)}
     
* methods will throw an exception.
     
* <p>
     
* If the field is a {@link ChronoField} then the query is implemented here.
     
* The supported fields are:
     
* <ul>
     
* <li>{@code NANO_OF_SECOND}
     
* <li>{@code MICRO_OF_SECOND}
     
* <li>{@code MILLI_OF_SECOND}
     
* <li>{@code INSTANT_SECONDS}
     
* </ul>
     
* All other {@code ChronoField} instances will return false.
     
* <p>
     
* If the field is not a {@code ChronoField}, then the result of this method
     
* is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
     
* passing {@code this} as the argument.
     
* Whether the field is supported is determined by the field.
     
*
     
* @param field
  
the field to check, null returns false
     
* @return true if the field is supported on this instant, false if not
     
*/

    
@Override
    
public boolean isSupported(TemporalField field) {
        
if (field instanceof ChronoField) {
            
return field == INSTANT_SECONDS || field == NANO_OF_SECOND || field == MICRO_OF_SECOND || field == MILLI_OF_SECOND;
        
}
        
return field != null && field.isSupportedBy(this);
    
}

    
/**
     
* Checks if the specified unit is supported.
     
* <p>
     
* This checks if the specified unit can be added to, or subtracted from, this date-time.
     
* If false, then calling the {@link #plus(long, TemporalUnit)} and
     
* {@link #minus(long, TemporalUnit) minus} methods will throw an exception.
     
* <p>
     
* If the unit is a {@link ChronoUnit} then the query is implemented here.
     
* The supported units are:
     
* <ul>
     
* <li>{@code NANOS}
     
* <li>{@code MICROS}
     
* <li>{@code MILLIS}
     
* <li>{@code SECONDS}
     
* <li>{@code MINUTES}
     
* <li>{@code HOURS}
     
* <li>{@code HALF_DAYS}
     
* <li>{@code DAYS}
     
* </ul>
     
* All other {@code ChronoUnit} instances will return false.
     
* <p>
     
* If the unit is not a {@code ChronoUnit}, then the result of this method
     
* is obtained by invoking {@code TemporalUnit.isSupportedBy(Temporal)}
     
* passing {@code this} as the argument.
     
* Whether the unit is supported is determined by the unit.
     
*
     
* @param unit
  
the unit to check, null returns false
     
* @return true if the unit can be added/subtracted, false if not
     
*/

    
@Override
    
public boolean isSupported(TemporalUnit unit) {
        
if (unit instanceof ChronoUnit) {
            
return unit.isTimeBased() || unit == DAYS;
        
}
        
return unit != null && unit.isSupportedBy(this);
    
}

    
//-----------------------------------------------------------------------
    
/**
     
* Gets the range of valid values for the specified field.
     
* <p>
     
* The range object expresses the minimum and maximum valid values for a field.
     
* This instant is used to enhance the accuracy of the returned range.
     
* If it is not possible to return the range, because the field is not supported
     
* or for some other reason, an exception is thrown.
     
* <p>
     
* If the field is a {@link ChronoField} then the query is implemented here.
     
* The {@link #isSupported(TemporalField) supported fields} will return
     
* appropriate range instances.
     
* All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
     
* <p>
     
* If the field is not a {@code ChronoField}, then the result of this method
     
* is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
     
* passing {@code this} as the argument.
     
* Whether the range can be obtained is determined by the field.
     
*
     
* @param field
  
the field to query the range for, not null
     
* @return the range of valid values for the field, not null
     
* @throws DateTimeException if the range for the field cannot be obtained
     
* @throws UnsupportedTemporalTypeException if the field is not supported
     
*/

    
@Override
  
// override for Javadoc
    
public ValueRange range(TemporalField field) {
        
return Temporal.super.range(field);
    
}

    
/**
     
* Gets the value of the specified field from this instant as an {@code int}.
     
* <p>
     
* This queries this instant for the value of the specified field.
     
* The returned value will always be within the valid range of values for the field.
     
* If it is not possible to return the value, because the field is not supported
     
* or for some other reason, an exception is thrown.
     
* <p>
     
* If the field is a {@link ChronoField} then the query is implemented here.
     
* The {@link #isSupported(TemporalField) supported fields} will return valid
     
* values based on this date-time, except {@code INSTANT_SECONDS} which is too
     
* large to fit in an {@code int} and throws a {@code DateTimeException}.
     
* All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
     
* <p>
     
* If the field is not a {@code ChronoField}, then the result of this method
     
* is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
     
* passing {@code this} as the argument. Whether the value can be obtained,
     
* and what the value represents, is determined by the field.
     
*
     
* @param field
  
the field to get, not null
     
* @return the value for the field
     
* @throws DateTimeException if a value for the field cannot be obtained or
     
*
         
the value is outside the range of valid values for the field
     
* @throws UnsupportedTemporalTypeException if the field is not supported or
     
*
         
the range of values exceeds an {@code int}
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
@Override
  
// override for Javadoc and performance
    
public int get(TemporalField field) {
        
if (field instanceof ChronoField) {
            
switch ((ChronoField) field) {
                
case NANO_OF_SECOND: return nanos;
                
case MICRO_OF_SECOND: return nanos / 1000;
                
case MILLI_OF_SECOND: return nanos / 1000_000;
                
case INSTANT_SECONDS: INSTANT_SECONDS.checkValidIntValue(seconds);
            
}
            
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
        
}
        
return range(field).checkValidIntValue(field.getFrom(this), field);
    
}

    
/**
     
* Gets the value of the specified field from this instant as a {@code long}.
     
* <p>
     
* This queries this instant for the value of the specified field.
     
* If it is not possible to return the value, because the field is not supported
     
* or for some other reason, an exception is thrown.
     
* <p>
     
* If the field is a {@link ChronoField} then the query is implemented here.
     
* The {@link #isSupported(TemporalField) supported fields} will return valid
     
* values based on this date-time.
     
* All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
     
* <p>
     
* If the field is not a {@code ChronoField}, then the result of this method
     
* is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
     
* passing {@code this} as the argument. Whether the value can be obtained,
     
* and what the value represents, is determined by the field.
     
*
     
* @param field
  
the field to get, not null
     
* @return the value for the field
     
* @throws DateTimeException if a value for the field cannot be obtained
     
* @throws UnsupportedTemporalTypeException if the field is not supported
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
@Override
    
public long getLong(TemporalField field) {
        
if (field instanceof ChronoField) {
            
switch ((ChronoField) field) {
                
case NANO_OF_SECOND: return nanos;
                
case MICRO_OF_SECOND: return nanos / 1000;
                
case MILLI_OF_SECOND: return nanos / 1000_000;
                
case INSTANT_SECONDS: return seconds;
            
}
            
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
        
}
        
return field.getFrom(this);
    
}

    
//-----------------------------------------------------------------------
    
/**
     
* Gets the number of seconds from the Java epoch of 1970-01-01T00:00:00Z.
     
* <p>
     
* The epoch second count is a simple incrementing count of seconds where
     
* second 0 is 1970-01-01T00:00:00Z.
     
* The nanosecond part of the day is returned by {@code getNanosOfSecond}.
     
*
     
* @return the seconds from the epoch of 1970-01-01T00:00:00Z
     
*/

    
public long getEpochSecond() {
        
return seconds;
    
}

    
/**
     
* Gets the number of nanoseconds, later along the time-line, from the start
     
* of the second.
     
* <p>
     
* The nanosecond-of-second value measures the total number of nanoseconds from
     
* the second returned by {@code getEpochSecond}.
     
*
     
* @return the nanoseconds within the second, always positive, never exceeds 999,999,999
     
*/

    
public int getNano() {
        
return nanos;
    
}

    
//-------------------------------------------------------------------------
    
/**
     
* Returns an adjusted copy of this instant.
     
* <p>
     
* This returns an {@code Instant}, based on this one, with the instant adjusted.
     
* The adjustment takes place using the specified adjuster strategy object.
     
* Read the documentation of the adjuster to understand what adjustment will be made.
     
* <p>
     
* The result of this method is obtained by invoking the
     
* {@link TemporalAdjuster#adjustInto(Temporal)} method on the
     
* specified adjuster passing {@code this} as the argument.
     
* <p>
     
* This instance is immutable and unaffected by this method call.
     
*
     
* @param adjuster the adjuster to use, not null
     
* @return an {@code Instant} based on {@code this} with the adjustment made, not null
     
* @throws DateTimeException if the adjustment cannot be made
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
@Override
    
public Instant with(TemporalAdjuster adjuster) {
        
return (Instant) adjuster.adjustInto(this);
    
}

    
/**
     
* Returns a copy of this instant with the specified field set to a new value.
     
* <p>
     
* This returns an {@code Instant}, based on this one, with the value
     
* for the specified field changed.
     
* If it is not possible to set the value, because the field is not supported or for
     
* some other reason, an exception is thrown.
     
* <p>
     
* If the field is a {@link ChronoField} then the adjustment is implemented here.
     
* The supported fields behave as follows:
     
* <ul>
     
* <li>{@code NANO_OF_SECOND} -
     
*
  
Returns an {@code Instant} with the specified nano-of-second.
     
*
  
The epoch-second will be unchanged.
     
* <li>{@code MICRO_OF_SECOND} -
     
*
  
Returns an {@code Instant} with the nano-of-second replaced by the specified
     
*
  
micro-of-second multiplied by 1,000. The epoch-second will be unchanged.
     
* <li>{@code MILLI_OF_SECOND} -
     
*
  
Returns an {@code Instant} with the nano-of-second replaced by the specified
     
*
  
milli-of-second multiplied by 1,000,000. The epoch-second will be unchanged.
     
* <li>{@code INSTANT_SECONDS} -
     
*
  
Returns an {@code Instant} with the specified epoch-second.
     
*
  
The nano-of-second will be unchanged.
     
* </ul>
     
* <p>
     
* In all cases, if the new value is outside the valid range of values for the field
     
* then a {@code DateTimeException} will be thrown.
     
* <p>
     
* All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
     
* <p>
     
* If the field is not a {@code ChronoField}, then the result of this method
     
* is obtained by invoking {@code TemporalField.adjustInto(Temporal, long)}
     
* passing {@code this} as the argument. In this case, the field determines
     
* whether and how to adjust the instant.
     
* <p>
     
* This instance is immutable and unaffected by this method call.
     
*
     
* @param field
  
the field to set in the result, not null
     
* @param newValue
  
the new value of the field in the result
     
* @return an {@code Instant} based on {@code this} with the specified field set, not null
     
* @throws DateTimeException if the field cannot be set
     
* @throws UnsupportedTemporalTypeException if the field is not supported
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
@Override
    
public Instant with(TemporalField field, long newValue) {
        
if (field instanceof ChronoField) {
            
ChronoField f = (ChronoField) field;
            
f.checkValidValue(newValue);
            
switch (f) {
                
case MILLI_OF_SECOND: {
                    
int nval = (int) newValue * 1000_000;
                    
return (nval != nanos ? create(seconds, nval) : this);
                
}
                
case MICRO_OF_SECOND: {
                    
int nval = (int) newValue * 1000;
                    
return (nval != nanos ? create(seconds, nval) : this);
                
}
                
case NANO_OF_SECOND: return (newValue != nanos ? create(seconds, (int) newValue) : this);
                
case INSTANT_SECONDS: return (newValue != seconds ? create(newValue, nanos) : this);
            
}
            
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
        
}
        
return field.adjustInto(this, newValue);
    
}

    
//-----------------------------------------------------------------------
    
/**
     
* Returns a copy of this {@code Instant} truncated to the specified unit.
     
* <p>
     
* Truncating the instant returns a copy of the original with fields
     
* smaller than the specified unit set to zero.
     
* The fields are calculated on the basis of using a UTC offset as seen
     
* in {@code toString}.
     
* For example, truncating with the {@link ChronoUnit#MINUTES MINUTES} unit will
     
* round down to the nearest minute, setting the seconds and nanoseconds to zero.
     
* <p>
     
* The unit must have a {@linkplain TemporalUnit#getDuration() duration}
     
* that divides into the length of a standard day without remainder.
     
* This includes all supplied time units on {@link ChronoUnit} and
     
* {@link ChronoUnit#DAYS DAYS}. Other units throw an exception.
     
* <p>
     
* This instance is immutable and unaffected by this method call.
     
*
     
* @param unit
  
the unit to truncate to, not null
     
* @return an {@code Instant} based on this instant with the time truncated, not null
     
* @throws DateTimeException if the unit is invalid for truncation
     
* @throws UnsupportedTemporalTypeException if the unit is not supported
     
*/

    
public Instant truncatedTo(TemporalUnit unit) {
        
if (unit == ChronoUnit.NANOS) {
            
return this;
        
}
        
Duration unitDur = unit.getDuration();
        
if (unitDur.getSeconds() > LocalTime.SECONDS_PER_DAY) {
            
throw new UnsupportedTemporalTypeException("Unit is too large to be used for truncation");
        
}
        
long dur = unitDur.toNanos();
        
if ((LocalTime.NANOS_PER_DAY % dur) != 0) {
            
throw new UnsupportedTemporalTypeException("Unit must divide into a standard day without remainder");
        
}
        
long nod = (seconds % LocalTime.SECONDS_PER_DAY) * LocalTime.NANOS_PER_SECOND + nanos;
        
long result = (nod / dur) * dur;
        
return plusNanos(result - nod);
    
}

    
//-----------------------------------------------------------------------
    
/**
     
* Returns a copy of this instant with the specified amount added.
     
* <p>
     
* This returns an {@code Instant}, based on this one, with the specified amount added.
     
* The amount is typically {@link Duration} but may be any other type implementing
     
* the {@link TemporalAmount} interface.
     
* <p>
     
* The calculation is delegated to the amount object by calling
     
* {@link TemporalAmount#addTo(Temporal)}. The amount implementation is free
     
* to implement the addition in any way it wishes, however it typically
     
* calls back to {@link #plus(long, TemporalUnit)}. Consult the documentation
     
* of the amount implementation to determine if it can be successfully added.
     
* <p>
     
* This instance is immutable and unaffected by this method call.
     
*
     
* @param amountToAdd
  
the amount to add, not null
     
* @return an {@code Instant} based on this instant with the addition made, not null
     
* @throws DateTimeException if the addition cannot be made
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
@Override
    
public Instant plus(TemporalAmount amountToAdd) {
        
return (Instant) amountToAdd.addTo(this);
    
}

    
/**
     
* Returns a copy of this instant with the specified amount added.
     
* <p>
     
* This returns an {@code Instant}, based on this one, with the amount
     
* in terms of the unit added. If it is not possible to add the amount, because the
     
* unit is not supported or for some other reason, an exception is thrown.
     
* <p>
     
* If the field is a {@link ChronoUnit} then the addition is implemented here.
     
* The supported fields behave as follows:
     
* <ul>
     
* <li>{@code NANOS} -
     
*
  
Returns a {@code Instant} with the specified number of nanoseconds added.
     
*
  
This is equivalent to {@link #plusNanos(long)}.
     
* <li>{@code MICROS} -
     
*
  
Returns a {@code Instant} with the specified number of microseconds added.
     
*
  
This is equivalent to {@link #plusNanos(long)} with the amount
     
*
  
multiplied by 1,000.
     
* <li>{@code MILLIS} -
     
*
  
Returns a {@code Instant} with the specified number of milliseconds added.
     
*
  
This is equivalent to {@link #plusNanos(long)} with the amount
     
*
  
multiplied by 1,000,000.
     
* <li>{@code SECONDS} -
     
*
  
Returns a {@code Instant} with the specified number of seconds added.
     
*
  
This is equivalent to {@link #plusSeconds(long)}.
     
* <li>{@code MINUTES} -
     
*
  
Returns a {@code Instant} with the specified number of minutes added.
     
*
  
This is equivalent to {@link #plusSeconds(long)} with the amount
     
*
  
multiplied by 60.
     
* <li>{@code HOURS} -
     
*
  
Returns a {@code Instant} with the specified number of hours added.
     
*
  
This is equivalent to {@link #plusSeconds(long)} with the amount
     
*
  
multiplied by 3,600.
     
* <li>{@code HALF_DAYS} -
     
*
  
Returns a {@code Instant} with the specified number of half-days added.
     
*
  
This is equivalent to {@link #plusSeconds(long)} with the amount
     
*
  
multiplied by 43,200 (12 hours).
     
* <li>{@code DAYS} -
     
*
  
Returns a {@code Instant} with the specified number of days added.
     
*
  
This is equivalent to {@link #plusSeconds(long)} with the amount
     
*
  
multiplied by 86,400 (24 hours).
     
* </ul>
     
* <p>
     
* All other {@code ChronoUnit} instances will throw an {@code UnsupportedTemporalTypeException}.
     
* <p>
     
* If the field is not a {@code ChronoUnit}, then the result of this method
     
* is obtained by invoking {@code TemporalUnit.addTo(Temporal, long)}
     
* passing {@code this} as the argument. In this case, the unit determines
     
* whether and how to perform the addition.
     
* <p>
     
* This instance is immutable and unaffected by this method call.
     
*
     
* @param amountToAdd
  
the amount of the unit to add to the result, may be negative
     
* @param unit
  
the unit of the amount to add, not null
     
* @return an {@code Instant} based on this instant with the specified amount added, not null
     
* @throws DateTimeException if the addition cannot be made
     
* @throws UnsupportedTemporalTypeException if the unit is not supported
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
@Override
    
public Instant plus(long amountToAdd, TemporalUnit unit) {
        
if (unit instanceof ChronoUnit) {
            
switch ((ChronoUnit) unit) {
                
case NANOS: return plusNanos(amountToAdd);
                
case MICROS: return plus(amountToAdd / 1000_000, (amountToAdd % 1000_000) * 1000);
                
case MILLIS: return plusMillis(amountToAdd);
                
case SECONDS: return plusSeconds(amountToAdd);
                
case MINUTES: return plusSeconds(Math.multiplyExact(amountToAdd, SECONDS_PER_MINUTE));
                
case HOURS: return plusSeconds(Math.multiplyExact(amountToAdd, SECONDS_PER_HOUR));
                
case HALF_DAYS: return plusSeconds(Math.multiplyExact(amountToAdd, SECONDS_PER_DAY / 2));
                
case DAYS: return plusSeconds(Math.multiplyExact(amountToAdd, SECONDS_PER_DAY));
            
}
            
throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
        
}
        
return unit.addTo(this, amountToAdd);
    
}

    
//-----------------------------------------------------------------------
    
/**
     
* Returns a copy of this instant with the specified duration in seconds added.
     
* <p>
     
* This instance is immutable and unaffected by this method call.
     
*
     
* @param secondsToAdd
  
the seconds to add, positive or negative
     
* @return an {@code Instant} based on this instant with the specified seconds added, not null
     
* @throws DateTimeException if the result exceeds the maximum or minimum instant
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
public Instant plusSeconds(long secondsToAdd) {
        
return plus(secondsToAdd, 0);
    
}

    
/**
     
* Returns a copy of this instant with the specified duration in milliseconds added.
     
* <p>
     
* This instance is immutable and unaffected by this method call.
     
*
     
* @param millisToAdd
  
the milliseconds to add, positive or negative
     
* @return an {@code Instant} based on this instant with the specified milliseconds added, not null
     
* @throws DateTimeException if the result exceeds the maximum or minimum instant
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
public Instant plusMillis(long millisToAdd) {
        
return plus(millisToAdd / 1000, (millisToAdd % 1000) * 1000_000);
    
}

    
/**
     
* Returns a copy of this instant with the specified duration in nanoseconds added.
     
* <p>
     
* This instance is immutable and unaffected by this method call.
     
*
     
* @param nanosToAdd
  
the nanoseconds to add, positive or negative
     
* @return an {@code Instant} based on this instant with the specified nanoseconds added, not null
     
* @throws DateTimeException if the result exceeds the maximum or minimum instant
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
public Instant plusNanos(long nanosToAdd) {
        
return plus(0, nanosToAdd);
    
}

    
/**
     
* Returns a copy of this instant with the specified duration added.
     
* <p>
     
* This instance is immutable and unaffected by this method call.
     
*
     
* @param secondsToAdd
  
the seconds to add, positive or negative
     
* @param nanosToAdd
  
the nanos to add, positive or negative
     
* @return an {@code Instant} based on this instant with the specified seconds added, not null
     
* @throws DateTimeException if the result exceeds the maximum or minimum instant
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
private Instant plus(long secondsToAdd, long nanosToAdd) {
        
if ((secondsToAdd | nanosToAdd) == 0) {
            
return this;
        
}
        
long epochSec = Math.addExact(seconds, secondsToAdd);
        
epochSec = Math.addExact(epochSec, nanosToAdd / NANOS_PER_SECOND);
        
nanosToAdd = nanosToAdd % NANOS_PER_SECOND;
        
long nanoAdjustment = nanos + nanosToAdd;
  
// safe int+NANOS_PER_SECOND
        
return ofEpochSecond(epochSec, nanoAdjustment);
    
}

    
//-----------------------------------------------------------------------
    
/**
     
* Returns a copy of this instant with the specified amount subtracted.
     
* <p>
     
* This returns an {@code Instant}, based on this one, with the specified amount subtracted.
     
* The amount is typically {@link Duration} but may be any other type implementing
     
* the {@link TemporalAmount} interface.
     
* <p>
     
* The calculation is delegated to the amount object by calling
     
* {@link TemporalAmount#subtractFrom(Temporal)}. The amount implementation is free
     
* to implement the subtraction in any way it wishes, however it typically
     
* calls back to {@link #minus(long, TemporalUnit)}. Consult the documentation
     
* of the amount implementation to determine if it can be successfully subtracted.
     
* <p>
     
* This instance is immutable and unaffected by this method call.
     
*
     
* @param amountToSubtract
  
the amount to subtract, not null
     
* @return an {@code Instant} based on this instant with the subtraction made, not null
     
* @throws DateTimeException if the subtraction cannot be made
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
@Override
    
public Instant minus(TemporalAmount amountToSubtract) {
        
return (Instant) amountToSubtract.subtractFrom(this);
    
}

    
/**
     
* Returns a copy of this instant with the specified amount subtracted.
     
* <p>
     
* This returns a {@code Instant}, based on this one, with the amount
     
* in terms of the unit subtracted. If it is not possible to subtract the amount,
     
* because the unit is not supported or for some other reason, an exception is thrown.
     
* <p>
     
* This method is equivalent to {@link #plus(long, TemporalUnit)} with the amount negated.
     
* See that method for a full description of how addition, and thus subtraction, works.
     
* <p>
     
* This instance is immutable and unaffected by this method call.
     
*
     
* @param amountToSubtract
  
the amount of the unit to subtract from the result, may be negative
     
* @param unit
  
the unit of the amount to subtract, not null
     
* @return an {@code Instant} based on this instant with the specified amount subtracted, not null
     
* @throws DateTimeException if the subtraction cannot be made
     
* @throws UnsupportedTemporalTypeException if the unit is not supported
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
@Override
    
public Instant minus(long amountToSubtract, TemporalUnit unit) {
        
return (amountToSubtract == Long.MIN_VALUE ? plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit));
    
}

    
//-----------------------------------------------------------------------
    
/**
     
* Returns a copy of this instant with the specified duration in seconds subtracted.
     
* <p>
     
* This instance is immutable and unaffected by this method call.
     
*
     
* @param secondsToSubtract
  
the seconds to subtract, positive or negative
     
* @return an {@code Instant} based on this instant with the specified seconds subtracted, not null
     
* @throws DateTimeException if the result exceeds the maximum or minimum instant
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
public Instant minusSeconds(long secondsToSubtract) {
        
if (secondsToSubtract == Long.MIN_VALUE) {
            
return plusSeconds(Long.MAX_VALUE).plusSeconds(1);
        
}
        
return plusSeconds(-secondsToSubtract);
    
}

    
/**
     
* Returns a copy of this instant with the specified duration in milliseconds subtracted.
     
* <p>
     
* This instance is immutable and unaffected by this method call.
     
*
     
* @param millisToSubtract
  
the milliseconds to subtract, positive or negative
     
* @return an {@code Instant} based on this instant with the specified milliseconds subtracted, not null
     
* @throws DateTimeException if the result exceeds the maximum or minimum instant
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
public Instant minusMillis(long millisToSubtract) {
        
if (millisToSubtract == Long.MIN_VALUE) {
            
return plusMillis(Long.MAX_VALUE).plusMillis(1);
        
}
        
return plusMillis(-millisToSubtract);
    
}

    
/**
     
* Returns a copy of this instant with the specified duration in nanoseconds subtracted.
     
* <p>
     
* This instance is immutable and unaffected by this method call.
     
*
     
* @param nanosToSubtract
  
the nanoseconds to subtract, positive or negative
     
* @return an {@code Instant} based on this instant with the specified nanoseconds subtracted, not null
     
* @throws DateTimeException if the result exceeds the maximum or minimum instant
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
public Instant minusNanos(long nanosToSubtract) {
        
if (nanosToSubtract == Long.MIN_VALUE) {
            
return plusNanos(Long.MAX_VALUE).plusNanos(1);
        
}
        
return plusNanos(-nanosToSubtract);
    
}

    
//-------------------------------------------------------------------------
    
/**
     
* Queries this instant using the specified query.
     
* <p>
     
* This queries this instant using the specified query strategy object.
     
* The {@code TemporalQuery} object defines the logic to be used to
     
* obtain the result. Read the documentation of the query to understand
     
* what the result of this method will be.
     
* <p>
     
* The result of this method is obtained by invoking the
     
* {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
     
* specified query passing {@code this} as the argument.
     
*
     
* @param <R> the type of the result
     
* @param query
  
the query to invoke, not null
     
* @return the query result, null may be returned (defined by the query)
     
* @throws DateTimeException if unable to query (defined by the query)
     
* @throws ArithmeticException if numeric overflow occurs (defined by the query)
     
*/

    
@SuppressWarnings("unchecked")
    
@Override
    
public <R> R query(TemporalQuery<R> query) {
        
if (query == TemporalQueries.precision()) {
            
return (R) NANOS;
        
}
        
// inline TemporalAccessor.super.query(query) as an optimization
        
if (query == TemporalQueries.chronology() || query == TemporalQueries.zoneId() ||
                
query == TemporalQueries.zone() || query == TemporalQueries.offset() ||
                
query == TemporalQueries.localDate() || query == TemporalQueries.localTime()) {
            
return null;
        
}
        
return query.queryFrom(this);
    
}

    
/**
     
* Adjusts the specified temporal object to have this instant.
     
* <p>
     
* This returns a temporal object of the same observable type as the input
     
* with the instant changed to be the same as this.
     
* <p>
     
* The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
     
* twice, passing {@link ChronoField#INSTANT_SECONDS} and
     
* {@link ChronoField#NANO_OF_SECOND} as the fields.
     
* <p>
     
* In most cases, it is clearer to reverse the calling pattern by using
     
* {@link Temporal#with(TemporalAdjuster)}:
     
* <pre>
     
*
   
// these two lines are equivalent, but the second approach is recommended
     
*
   
temporal = thisInstant.adjustInto(temporal);
     
*
   
temporal = temporal.with(thisInstant);
     
* </pre>
     
* <p>
     
* This instance is immutable and unaffected by this method call.
     
*
     
* @param temporal
  
the target object to be adjusted, not null
     
* @return the adjusted object, not null
     
* @throws DateTimeException if unable to make the adjustment
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
@Override
    
public Temporal adjustInto(Temporal temporal) {
        
return temporal.with(INSTANT_SECONDS, seconds).with(NANO_OF_SECOND, nanos);
    
}

    
/**
     
* Calculates the amount of time until another instant in terms of the specified unit.
     
* <p>
     
* This calculates the amount of time between two {@code Instant}
     
* objects in terms of a single {@code TemporalUnit}.
     
* The start and end points are {@code this} and the specified instant.
     
* The result will be negative if the end is before the start.
     
* The calculation returns a whole number, representing the number of
     
* complete units between the two instants.
     
* The {@code Temporal} passed to this method is converted to a
     
* {@code Instant} using {@link #from(TemporalAccessor)}.
     
* For example, the amount in days between two dates can be calculated
     
* using {@code startInstant.until(endInstant, SECONDS)}.
     
* <p>
     
* There are two equivalent ways of using this method.
     
* The first is to invoke this method.
     
* The second is to use {@link TemporalUnit#between(Temporal, Temporal)}:
     
* <pre>
     
*
   
// these two lines are equivalent
     
*
   
amount = start.until(end, SECONDS);
     
*
   
amount = SECONDS.between(start, end);
     
* </pre>
     
* The choice should be made based on which makes the code more readable.
     
* <p>
     
* The calculation is implemented in this method for {@link ChronoUnit}.
     
* The units {@code NANOS}, {@code MICROS}, {@code MILLIS}, {@code SECONDS},
     
* {@code MINUTES}, {@code HOURS}, {@code HALF_DAYS} and {@code DAYS}
     
* are supported. Other {@code ChronoUnit} values will throw an exception.
     
* <p>
     
* If the unit is not a {@code ChronoUnit}, then the result of this method
     
* is obtained by invoking {@code TemporalUnit.between(Temporal, Temporal)}
     
* passing {@code this} as the first argument and the converted input temporal
     
* as the second argument.
     
* <p>
     
* This instance is immutable and unaffected by this method call.
     
*
     
* @param endExclusive
  
the end date, exclusive, which is converted to an {@code Instant}, not null
     
* @param unit
  
the unit to measure the amount in, not null
     
* @return the amount of time between this instant and the end instant
     
* @throws DateTimeException if the amount cannot be calculated, or the end
     
*
  
temporal cannot be converted to an {@code Instant}
     
* @throws UnsupportedTemporalTypeException if the unit is not supported
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
@Override
    
public long until(Temporal endExclusive, TemporalUnit unit) {
        
Instant end = Instant.from(endExclusive);
        
if (unit instanceof ChronoUnit) {
            
ChronoUnit f = (ChronoUnit) unit;
            
switch (f) {
                
case NANOS: return nanosUntil(end);
                
case MICROS: return nanosUntil(end) / 1000;
                
case MILLIS: return Math.subtractExact(end.toEpochMilli(), toEpochMilli());
                
case SECONDS: return secondsUntil(end);
                
case MINUTES: return secondsUntil(end) / SECONDS_PER_MINUTE;
                
case HOURS: return secondsUntil(end) / SECONDS_PER_HOUR;
                
case HALF_DAYS: return secondsUntil(end) / (12 * SECONDS_PER_HOUR);
                
case DAYS: return secondsUntil(end) / (SECONDS_PER_DAY);
            
}
            
throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
        
}
        
return unit.between(this, end);
    
}

    
private long nanosUntil(Instant end) {
        
long secsDiff = Math.subtractExact(end.seconds, seconds);
        
long totalNanos = Math.multiplyExact(secsDiff, NANOS_PER_SECOND);
        
return Math.addExact(totalNanos, end.nanos - nanos);
    
}

    
private long secondsUntil(Instant end) {
        
long secsDiff = Math.subtractExact(end.seconds, seconds);
        
long nanosDiff = end.nanos - nanos;
        
if (secsDiff > 0 && nanosDiff < 0) {
            
secsDiff--;
        
} else if (secsDiff < 0 && nanosDiff > 0) {
            
secsDiff++;
        
}
        
return secsDiff;
    
}

    
//-----------------------------------------------------------------------
    
/**
     
* Combines this instant with an offset to create an {@code OffsetDateTime}.
     
* <p>
     
* This returns an {@code OffsetDateTime} formed from this instant at the
     
* specified offset from UTC/Greenwich. An exception will be thrown if the
     
* instant is too large to fit into an offset date-time.
     
* <p>
     
* This method is equivalent to
     
* {@link OffsetDateTime#ofInstant(Instant, ZoneId) OffsetDateTime.ofInstant(this, offset)}.
     
*
     
* @param offset
  
the offset to combine with, not null
     
* @return the offset date-time formed from this instant and the specified offset, not null
     
* @throws DateTimeException if the result exceeds the supported range
     
*/

    
public OffsetDateTime atOffset(ZoneOffset offset) {
        
return OffsetDateTime.ofInstant(this, offset);
    
}

    
/**
     
* Combines this instant with a time-zone to create a {@code ZonedDateTime}.
     
* <p>
     
* This returns an {@code ZonedDateTime} formed from this instant at the
     
* specified time-zone. An exception will be thrown if the instant is too
     
* large to fit into a zoned date-time.
     
* <p>
     
* This method is equivalent to
     
* {@link ZonedDateTime#ofInstant(Instant, ZoneId) ZonedDateTime.ofInstant(this, zone)}.
     
*
     
* @param zone
  
the zone to combine with, not null
     
* @return the zoned date-time formed from this instant and the specified zone, not null
     
* @throws DateTimeException if the result exceeds the supported range
     
*/

    
public ZonedDateTime atZone(ZoneId zone) {
        
return ZonedDateTime.ofInstant(this, zone);
    
}

    
//-----------------------------------------------------------------------
    
/**
     
* Converts this instant to the number of milliseconds from the epoch
     
* of 1970-01-01T00:00:00Z.
     
* <p>
     
* If this instant represents a point on the time-line too far in the future
     
* or past to fit in a {@code long} milliseconds, then an exception is thrown.
     
* <p>
     
* If this instant has greater than millisecond precision, then the conversion
     
* will drop any excess precision information as though the amount in nanoseconds
     
* was subject to integer division by one million.
     
*
     
* @return the number of milliseconds since the epoch of 1970-01-01T00:00:00Z
     
* @throws ArithmeticException if numeric overflow occurs
     
*/

    
public long toEpochMilli() {
        
if (seconds < 0 && nanos > 0) {
            
long millis = Math.multiplyExact(seconds+1, 1000);
            
long adjustment = nanos / 1000_000 - 1000;
            
return Math.addExact(millis, adjustment);
        
} else {
            
long millis = Math.multiplyExact(seconds, 1000);
            
return Math.addExact(millis, nanos / 1000_000);
        
}
    
}

    
//-----------------------------------------------------------------------
    
/**
     
* Compares this instant to the specified instant.
     
* <p>
     
* The comparison is based on the time-line position of the instants.
     
* It is "consistent with equals", as defined by {@link Comparable}.
     
*
     
* @param otherInstant
  
the other instant to compare to, not null
     
* @return the comparator value, negative if less, positive if greater
     
* @throws NullPointerException if otherInstant is null
     
*/

    
@Override
    
public int compareTo(Instant otherInstant) {
        
int cmp = Long.compare(seconds, otherInstant.seconds);
        
if (cmp != 0) {
            
return cmp;
        
}
        
return nanos - otherInstant.nanos;
    
}

    
/**
     
* Checks if this instant is after the specified instant.
     
* <p>
     
* The comparison is based on the time-line position of the instants.
     
*
     
* @param otherInstant
  
the other instant to compare to, not null
     
* @return true if this instant is after the specified instant
     
* @throws NullPointerException if otherInstant is null
     
*/

    
public boolean isAfter(Instant otherInstant) {
        
return compareTo(otherInstant) > 0;
    
}

    
/**
     
* Checks if this instant is before the specified instant.
     
* <p>
     
* The comparison is based on the time-line position of the instants.
     
*
     
* @param otherInstant
  
the other instant to compare to, not null
     
* @return true if this instant is before the specified instant
     
* @throws NullPointerException if otherInstant is null
     
*/

    
public boolean isBefore(Instant otherInstant) {
        
return compareTo(otherInstant) < 0;
    
}

    
//-----------------------------------------------------------------------
    
/**
     
* Checks if this instant is equal to the specified instant.
     
* <p>
     
* The comparison is based on the time-line position of the instants.
     
*
     
* @param otherInstant
  
the other instant, null returns false
     
* @return true if the other instant is equal to this one
     
*/

    
@Override
    
public boolean equals(Object otherInstant) {
        
if (this == otherInstant) {
            
return true;
        
}
        
if (otherInstant instanceof Instant) {
            
Instant other = (Instant) otherInstant;
            
return this.seconds == other.seconds &&
                   
this.nanos == other.nanos;
        
}
        
return false;
    
}

    
/**
     
* Returns a hash code for this instant.
     
*
     
* @return a suitable hash code
     
*/
    
@Override
    
public int hashCode() {
        
return ((int) (seconds ^ (seconds >>> 32))) + 51 * nanos;
    
}

    
//-----------------------------------------------------------------------
    
/**
     
* A string representation of this instant using ISO-8601 representation.
     
* <p>
     
* The format used is the same as {@link DateTimeFormatter#ISO_INSTANT}.
     
*
     
* @return an ISO-8601 representation of this instant, not null
     
*/

    
@Override
    
public String toString() {
        
return DateTimeFormatter.ISO_INSTANT.format(this);
    
}

    
// -----------------------------------------------------------------------
    
/**
     
* Writes the object using a
     
*
 
<a href="../../serialized-form.html#java.time.Ser">dedicated serialized form</a>.
     
* @serialData
     
* <pre>
     
*
  
out.writeByte(2);// identifies an Instant
     
*
  
out.writeLong(seconds);
     
*
  
out.writeInt(nanos);
     
* </pre>
     
*
     
* @return the instance of {@code Ser}, not null
     
*/

    
private Object writeReplace() {
        
return new Ser(Ser.INSTANT_TYPE, this);
    
}

    
/**
     
* Defend against malicious streams.
     
*
     
* @param s the stream to read
     
* @throws InvalidObjectException always
     
*/

    
private void readObject(ObjectInputStream s) throws InvalidObjectException {
        
throw new InvalidObjectException("Deserialization via serialization delegate");
    
}

    
void writeExternal(DataOutput out) throws IOException {
        
out.writeLong(seconds);
        
out.writeInt(nanos);
    
}

    
static Instant readExternal(DataInput in) throws IOException {
        
long seconds = in.readLong();
        
int nanos = in.readInt();
        
return Instant.ofEpochSecond(seconds, nanos);
    
}

}