src/share/classes/java/time/LocalDate.java

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@@ -78,30 +78,26 @@
 import java.io.DataOutput;
 import java.io.IOException;
 import java.io.InvalidObjectException;
 import java.io.ObjectStreamException;
 import java.io.Serializable;
-import java.time.format.DateTimeBuilder;
+import java.time.chrono.ChronoLocalDate;
+import java.time.chrono.Era;
+import java.time.chrono.IsoChronology;
 import java.time.format.DateTimeFormatter;
-import java.time.format.DateTimeFormatters;
 import java.time.format.DateTimeParseException;
 import java.time.temporal.ChronoField;
-import java.time.temporal.ChronoLocalDate;
 import java.time.temporal.ChronoUnit;
-import java.time.temporal.Era;
-import java.time.temporal.ISOChrono;
-import java.time.temporal.OffsetDate;
+import java.time.temporal.Queries;
 import java.time.temporal.Temporal;
 import java.time.temporal.TemporalAccessor;
-import java.time.temporal.TemporalAdder;
 import java.time.temporal.TemporalAdjuster;
+import java.time.temporal.TemporalAmount;
 import java.time.temporal.TemporalField;
 import java.time.temporal.TemporalQuery;
-import java.time.temporal.TemporalSubtractor;
 import java.time.temporal.TemporalUnit;
 import java.time.temporal.ValueRange;
-import java.time.temporal.Year;
 import java.time.zone.ZoneOffsetTransition;
 import java.time.zone.ZoneRules;
 import java.util.Objects;
 
 /**

@@ -129,11 +125,11 @@
  * This class is immutable and thread-safe.
  *
  * @since 1.8
  */
 public final class LocalDate
-        implements Temporal, TemporalAdjuster, ChronoLocalDate<ISOChrono>, Serializable {
+        implements Temporal, TemporalAdjuster, ChronoLocalDate<LocalDate>, Serializable {
 
     /**
      * The minimum supported {@code LocalDate}, '-999999999-01-01'.
      * This could be used by an application as a "far past" date.
      */

@@ -214,11 +210,11 @@
      * @param clock  the clock to use, not null
      * @return the current date, not null
      */
     public static LocalDate now(Clock clock) {
         Objects.requireNonNull(clock, "clock");
-        // inline OffsetDate factory to avoid creating object and InstantProvider checks
+        // inline to avoid creating object and Instant checks
         final Instant now = clock.instant();  // called once
         ZoneOffset offset = clock.getZone().getRules().getOffset(now);
         long epochSec = now.getEpochSecond() + offset.getTotalSeconds();  // overflow caught later
         long epochDay = Math.floorDiv(epochSec, SECONDS_PER_DAY);
         return LocalDate.ofEpochDay(epochDay);

@@ -226,18 +222,19 @@
 
     //-----------------------------------------------------------------------
     /**
      * Obtains an instance of {@code LocalDate} from a year, month and day.
      * <p>
+     * This returns a {@code LocalDate} with the specified year, month and day-of-month.
      * The day must be valid for the year and month, otherwise an exception will be thrown.
      *
      * @param year  the year to represent, from MIN_YEAR to MAX_YEAR
      * @param month  the month-of-year to represent, not null
      * @param dayOfMonth  the day-of-month to represent, from 1 to 31
      * @return the local date, not null
-     * @throws DateTimeException if the value of any field is out of range
-     * @throws DateTimeException if the day-of-month is invalid for the month-year
+     * @throws DateTimeException if the value of any field is out of range,
+     *  or if the day-of-month is invalid for the month-year
      */
     public static LocalDate of(int year, Month month, int dayOfMonth) {
         YEAR.checkValidValue(year);
         Objects.requireNonNull(month, "month");
         DAY_OF_MONTH.checkValidValue(dayOfMonth);

@@ -245,18 +242,19 @@
     }
 
     /**
      * Obtains an instance of {@code LocalDate} from a year, month and day.
      * <p>
+     * This returns a {@code LocalDate} with the specified year, month and day-of-month.
      * The day must be valid for the year and month, otherwise an exception will be thrown.
      *
      * @param year  the year to represent, from MIN_YEAR to MAX_YEAR
      * @param month  the month-of-year to represent, from 1 (January) to 12 (December)
      * @param dayOfMonth  the day-of-month to represent, from 1 to 31
      * @return the local date, not null
-     * @throws DateTimeException if the value of any field is out of range
-     * @throws DateTimeException if the day-of-month is invalid for the month-year
+     * @throws DateTimeException if the value of any field is out of range,
+     *  or if the day-of-month is invalid for the month-year
      */
     public static LocalDate of(int year, int month, int dayOfMonth) {
         YEAR.checkValidValue(year);
         MONTH_OF_YEAR.checkValidValue(month);
         DAY_OF_MONTH.checkValidValue(dayOfMonth);

@@ -265,22 +263,23 @@
 
     //-----------------------------------------------------------------------
     /**
      * Obtains an instance of {@code LocalDate} from a year and day-of-year.
      * <p>
+     * This returns a {@code LocalDate} with the specified year and day-of-year.
      * The day-of-year must be valid for the year, otherwise an exception will be thrown.
      *
      * @param year  the year to represent, from MIN_YEAR to MAX_YEAR
      * @param dayOfYear  the day-of-year to represent, from 1 to 366
      * @return the local date, not null
-     * @throws DateTimeException if the value of any field is out of range
-     * @throws DateTimeException if the day-of-year is invalid for the month-year
+     * @throws DateTimeException if the value of any field is out of range,
+     *  or if the day-of-year is invalid for the month-year
      */
     public static LocalDate ofYearDay(int year, int dayOfYear) {
         YEAR.checkValidValue(year);
         DAY_OF_YEAR.checkValidValue(dayOfYear);
-        boolean leap = ISOChrono.INSTANCE.isLeapYear(year);
+        boolean leap = IsoChronology.INSTANCE.isLeapYear(year);
         if (dayOfYear == 366 && leap == false) {
             throw new DateTimeException("Invalid date 'DayOfYear 366' as '" + year + "' is not a leap year");
         }
         Month moy = Month.of((dayOfYear - 1) / 31 + 1);
         int monthEnd = moy.firstDayOfYear(leap) + moy.length(leap) - 1;

@@ -293,12 +292,13 @@
 
     //-----------------------------------------------------------------------
     /**
      * Obtains an instance of {@code LocalDate} from the epoch day count.
      * <p>
-     * The Epoch Day count is a simple incrementing count of days
-     * where day 0 is 1970-01-01. Negative numbers represent earlier days.
+     * This returns a {@code LocalDate} with the specified epoch-day.
+     * The {@link ChronoField#EPOCH_DAY EPOCH_DAY} is a simple incrementing count
+     * of days where day 0 is 1970-01-01. Negative numbers represent earlier days.
      *
      * @param epochDay  the Epoch Day to convert, based on the epoch 1970-01-01
      * @return the local date, not null
      * @throws DateTimeException if the epoch days exceeds the supported date range
      */

@@ -336,58 +336,45 @@
 
     //-----------------------------------------------------------------------
     /**
      * Obtains an instance of {@code LocalDate} from a temporal object.
      * <p>
-     * A {@code TemporalAccessor} represents some form of date and time information.
-     * This factory converts the arbitrary temporal object to an instance of {@code LocalDate}.
+     * This obtains a local date 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 LocalDate}.
      * <p>
-     * The conversion extracts the {@link ChronoField#EPOCH_DAY EPOCH_DAY} field.
+     * The conversion uses the {@link Queries#localDate()} query, which relies
+     * on extracting the {@link ChronoField#EPOCH_DAY EPOCH_DAY} field.
      * <p>
      * This method matches the signature of the functional interface {@link TemporalQuery}
      * allowing it to be used as a query via method reference, {@code LocalDate::from}.
      *
      * @param temporal  the temporal object to convert, not null
      * @return the local date, not null
      * @throws DateTimeException if unable to convert to a {@code LocalDate}
      */
     public static LocalDate from(TemporalAccessor temporal) {
-        if (temporal instanceof LocalDate) {
-            return (LocalDate) temporal;
-        } else if (temporal instanceof LocalDateTime) {
-            return ((LocalDateTime) temporal).getDate();
-        } else if (temporal instanceof ZonedDateTime) {
-            return ((ZonedDateTime) temporal).getDate();
-        }
-        // handle builder as a special case
-        if (temporal instanceof DateTimeBuilder) {
-            DateTimeBuilder builder = (DateTimeBuilder) temporal;
-            LocalDate date = builder.extract(LocalDate.class);
-            if (date != null) {
-                return date;
-            }
-        }
-        try {
-            return ofEpochDay(temporal.getLong(EPOCH_DAY));
-        } catch (DateTimeException ex) {
-            throw new DateTimeException("Unable to obtain LocalDate from TemporalAccessor: " + temporal.getClass(), ex);
+        LocalDate date = temporal.query(Queries.localDate());
+        if (date == null) {
+            throw new DateTimeException("Unable to obtain LocalDate from TemporalAccessor: " + temporal.getClass());
         }
+        return date;
     }
 
     //-----------------------------------------------------------------------
     /**
      * Obtains an instance of {@code LocalDate} from a text string such as {@code 2007-12-03}.
      * <p>
      * The string must represent a valid date and is parsed using
-     * {@link java.time.format.DateTimeFormatters#isoLocalDate()}.
+     * {@link java.time.format.DateTimeFormatter#ISO_LOCAL_DATE}.
      *
      * @param text  the text to parse such as "2007-12-03", not null
      * @return the parsed local date, not null
      * @throws DateTimeParseException if the text cannot be parsed
      */
     public static LocalDate parse(CharSequence text) {
-        return parse(text, DateTimeFormatters.isoLocalDate());
+        return parse(text, DateTimeFormatter.ISO_LOCAL_DATE);
     }
 
     /**
      * Obtains an instance of {@code LocalDate} from a text string using a specific formatter.
      * <p>

@@ -412,11 +399,11 @@
      * @param dayOfMonth  the day-of-month to represent, validated from 1 to 31
      * @return the local date, not null
      * @throws DateTimeException if the day-of-month is invalid for the month-year
      */
     private static LocalDate create(int year, Month month, int dayOfMonth) {
-        if (dayOfMonth > 28 && dayOfMonth > month.length(ISOChrono.INSTANCE.isLeapYear(year))) {
+        if (dayOfMonth > 28 && dayOfMonth > month.length(IsoChronology.INSTANCE.isLeapYear(year))) {
             if (dayOfMonth == 29) {
                 throw new DateTimeException("Invalid date 'February 29' as '" + year + "' is not a leap year");
             } else {
                 throw new DateTimeException("Invalid date '" + month.name() + " " + dayOfMonth + "'");
             }

@@ -433,11 +420,11 @@
      * @return the resolved date, not null
      */
     private static LocalDate resolvePreviousValid(int year, int month, int day) {
         switch (month) {
             case 2:
-                day = Math.min(day, ISOChrono.INSTANCE.isLeapYear(year) ? 29 : 28);
+                day = Math.min(day, IsoChronology.INSTANCE.isLeapYear(year) ? 29 : 28);
                 break;
             case 4:
             case 6:
             case 9:
             case 11:

@@ -467,12 +454,10 @@
      * This checks if this date can be queried for the specified field.
      * If false, then calling the {@link #range(TemporalField) range} and
      * {@link #get(TemporalField) get} methods will throw an exception.
      * <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.
      * The supported fields are:
      * <ul>
      * <li>{@code DAY_OF_WEEK}
      * <li>{@code ALIGNED_DAY_OF_WEEK_IN_MONTH}
      * <li>{@code ALIGNED_DAY_OF_WEEK_IN_YEAR}

@@ -488,11 +473,11 @@
      * <li>{@code ERA}
      * </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.doIsSupported(TemporalAccessor)}
+     * 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 date, false if not

@@ -514,11 +499,11 @@
      * The {@link #isSupported(TemporalField) supported fields} will return
      * appropriate range instances.
      * All other {@code ChronoField} instances will throw a {@code DateTimeException}.
      * <p>
      * If the field is not a {@code ChronoField}, then the result of this method
-     * is obtained by invoking {@code TemporalField.doRange(TemporalAccessor)}
+     * 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

@@ -538,11 +523,11 @@
                 }
                 return field.range();
             }
             throw new DateTimeException("Unsupported field: " + field.getName());
         }
-        return field.doRange(this);
+        return field.rangeRefinedBy(this);
     }
 
     /**
      * Gets the value of the specified field from this date as an {@code int}.
      * <p>

@@ -556,11 +541,11 @@
      * values based on this date, except {@code EPOCH_DAY} and {@code EPOCH_MONTH}
      * which are too large to fit in an {@code int} and throw a {@code DateTimeException}.
      * All other {@code ChronoField} instances will throw a {@code DateTimeException}.
      * <p>
      * If the field is not a {@code ChronoField}, then the result of this method
-     * is obtained by invoking {@code TemporalField.doGet(TemporalAccessor)}
+     * 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

@@ -586,11 +571,11 @@
      * The {@link #isSupported(TemporalField) supported fields} will return valid
      * values based on this date.
      * All other {@code ChronoField} instances will throw a {@code DateTimeException}.
      * <p>
      * If the field is not a {@code ChronoField}, then the result of this method
-     * is obtained by invoking {@code TemporalField.doGet(TemporalAccessor)}
+     * 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

@@ -606,11 +591,11 @@
             if (field == EPOCH_MONTH) {
                 return getEpochMonth();
             }
             return get0(field);
         }
-        return field.doGet(this);
+        return field.getFrom(this);
     }
 
     private int get0(TemporalField field) {
         switch ((ChronoField) field) {
             case DAY_OF_WEEK: return getDayOfWeek().getValue();

@@ -636,52 +621,52 @@
 
     //-----------------------------------------------------------------------
     /**
      * Gets the chronology of this date, which is the ISO calendar system.
      * <p>
-     * The {@code Chrono} represents the calendar system in use.
+     * The {@code Chronology} represents the calendar system in use.
      * The ISO-8601 calendar system is the modern civil calendar system used today
      * in most of the world. It is equivalent to the proleptic Gregorian calendar
      * system, in which todays's rules for leap years are applied for all time.
      *
      * @return the ISO chronology, not null
      */
     @Override
-    public ISOChrono getChrono() {
-        return ISOChrono.INSTANCE;
+    public IsoChronology getChronology() {
+        return IsoChronology.INSTANCE;
     }
 
     /**
      * Gets the era applicable at this date.
      * <p>
-     * The official ISO-8601 standard does not define eras, however {@code ISOChrono} does.
+     * The official ISO-8601 standard does not define eras, however {@code IsoChronology} does.
      * It defines two eras, 'CE' from year one onwards and 'BCE' from year zero backwards.
      * Since dates before the Julian-Gregorian cutover are not in line with history,
      * the cutover between 'BCE' and 'CE' is also not aligned with the commonly used
      * eras, often referred to using 'BC' and 'AD'.
      * <p>
      * Users of this class should typically ignore this method as it exists primarily
      * to fulfill the {@link ChronoLocalDate} contract where it is necessary to support
      * the Japanese calendar system.
      * <p>
      * The returned era will be a singleton capable of being compared with the constants
-     * in {@link ISOChrono} using the {@code ==} operator.
+     * in {@link IsoChronology} using the {@code ==} operator.
      *
-     * @return the {@code ISOChrono} era constant applicable at this date, not null
+     * @return the {@code IsoChronology} era constant applicable at this date, not null
      */
     @Override // override for Javadoc
-    public Era<ISOChrono> getEra() {
+    public Era getEra() {
         return ChronoLocalDate.super.getEra();
     }
 
     /**
      * Gets the year field.
      * <p>
      * This method returns the primitive {@code int} value for the year.
      * <p>
      * The year returned by this method is proleptic as per {@code get(YEAR)}.
-     * To obtain the year-of-era, use {@code get(YEAR_OF_ERA}.
+     * To obtain the year-of-era, use {@code get(YEAR_OF_ERA)}.
      *
      * @return the year, from MIN_YEAR to MAX_YEAR
      */
     public int getYear() {
         return year;

@@ -775,11 +760,11 @@
      *
      * @return true if the year is leap, false otherwise
      */
     @Override // override for Javadoc and performance
     public boolean isLeapYear() {
-        return ISOChrono.INSTANCE.isLeapYear(year);
+        return IsoChronology.INSTANCE.isLeapYear(year);
     }
 
     /**
      * Returns the length of the month represented by this date.
      * <p>

@@ -817,20 +802,20 @@
 
     //-----------------------------------------------------------------------
     /**
      * Returns an adjusted copy of this date.
      * <p>
-     * This returns a new {@code LocalDate}, based on this one, with the date adjusted.
+     * This returns a {@code LocalDate}, based on this one, with the date 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>
      * A simple adjuster might simply set the one of the fields, such as the year field.
      * A more complex adjuster might set the date to the last day of the month.
      * A selection of common adjustments is provided in {@link java.time.temporal.Adjusters}.
      * These include finding the "last day of the month" and "next Wednesday".
      * Key date-time classes also implement the {@code TemporalAdjuster} interface,
-     * such as {@link Month} and {@link java.time.temporal.MonthDay MonthDay}.
+     * such as {@link Month} and {@link java.time.MonthDay MonthDay}.
      * The adjuster is responsible for handling special cases, such as the varying
      * lengths of month and leap years.
      * <p>
      * For example this code returns a date on the last day of July:
      * <pre>

@@ -861,11 +846,11 @@
     }
 
     /**
      * Returns a copy of this date with the specified field set to a new value.
      * <p>
-     * This returns a new {@code LocalDate}, based on this one, with the value
+     * This returns a {@code LocalDate}, based on this one, with the value
      * for the specified field changed.
      * This can be used to change any supported field, such as the year, month or day-of-month.
      * 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>

@@ -949,11 +934,11 @@
      * then a {@code DateTimeException} will be thrown.
      * <p>
      * All other {@code ChronoField} instances will throw a {@code DateTimeException}.
      * <p>
      * If the field is not a {@code ChronoField}, then the result of this method
-     * is obtained by invoking {@code TemporalField.doWith(Temporal, long)}
+     * 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.
      *

@@ -983,11 +968,11 @@
                 case YEAR: return withYear((int) newValue);
                 case ERA: return (getLong(ERA) == newValue ? this : withYear(1 - year));
             }
             throw new DateTimeException("Unsupported field: " + field.getName());
         }
-        return field.doWith(this, newValue);
+        return field.adjustInto(this, newValue);
     }
 
     //-----------------------------------------------------------------------
     /**
      * Returns a copy of this date with the year altered.

@@ -1031,12 +1016,12 @@
      * <p>
      * This instance is immutable and unaffected by this method call.
      *
      * @param dayOfMonth  the day-of-month to set in the result, from 1 to 28-31
      * @return a {@code LocalDate} based on this date with the requested day, not null
-     * @throws DateTimeException if the day-of-month value is invalid
-     * @throws DateTimeException if the day-of-month is invalid for the month-year
+     * @throws DateTimeException if the day-of-month value is invalid,
+     *  or if the day-of-month is invalid for the month-year
      */
     public LocalDate withDayOfMonth(int dayOfMonth) {
         if (this.day == dayOfMonth) {
             return this;
         }

@@ -1049,56 +1034,125 @@
      * <p>
      * This instance is immutable and unaffected by this method call.
      *
      * @param dayOfYear  the day-of-year to set in the result, from 1 to 365-366
      * @return a {@code LocalDate} based on this date with the requested day, not null
-     * @throws DateTimeException if the day-of-year value is invalid
-     * @throws DateTimeException if the day-of-year is invalid for the year
+     * @throws DateTimeException if the day-of-year value is invalid,
+     *  or if the day-of-year is invalid for the year
      */
     public LocalDate withDayOfYear(int dayOfYear) {
         if (this.getDayOfYear() == dayOfYear) {
             return this;
         }
         return ofYearDay(year, dayOfYear);
     }
 
     //-----------------------------------------------------------------------
     /**
-     * Returns a copy of this date with the specified period added.
+     * Returns a copy of this date with the specified amount added.
+     * <p>
+     * This returns a {@code LocalDate}, based on this one, with the specified amount added.
+     * The amount is typically {@link Period} but may be any other type implementing
+     * the {@link TemporalAmount} interface.
      * <p>
-     * This method returns a new date based on this date with the specified period added.
-     * The adder is typically {@link Period} but may be any other type implementing
-     * the {@link TemporalAdder} interface.
-     * The calculation is delegated to the specified adjuster, which typically calls
-     * back to {@link #plus(long, TemporalUnit)}.
+     * 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 adder  the adder to use, not null
+     * @param amountToAdd  the amount to add, not null
      * @return a {@code LocalDate} based on this date with the addition made, not null
      * @throws DateTimeException if the addition cannot be made
      * @throws ArithmeticException if numeric overflow occurs
      */
     @Override
-    public LocalDate plus(TemporalAdder adder) {
-        return (LocalDate) adder.addTo(this);
+    public LocalDate plus(TemporalAmount amountToAdd) {
+        return (LocalDate) amountToAdd.addTo(this);
     }
 
     /**
-     * Returns a copy of this date with the specified period added.
+     * Returns a copy of this date with the specified amount added.
+     * <p>
+     * This returns a {@code LocalDate}, 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>
+     * In some cases, adding the amount can cause the resulting date to become invalid.
+     * For example, adding one month to 31st January would result in 31st February.
+     * In cases like this, the unit is responsible for resolving the date.
+     * Typically it will choose the previous valid date, which would be the last valid
+     * day of February in this example.
+     * <p>
+     * If the field is a {@link ChronoUnit} then the addition is implemented here.
+     * The supported fields behave as follows:
+     * <ul>
+     * <li>{@code DAYS} -
+     *  Returns a {@code LocalDate} with the specified number of days added.
+     *  This is equivalent to {@link #plusDays(long)}.
+     * <li>{@code WEEKS} -
+     *  Returns a {@code LocalDate} with the specified number of weeks added.
+     *  This is equivalent to {@link #plusWeeks(long)} and uses a 7 day week.
+     * <li>{@code MONTHS} -
+     *  Returns a {@code LocalDate} with the specified number of months added.
+     *  This is equivalent to {@link #plusMonths(long)}.
+     *  The day-of-month will be unchanged unless it would be invalid for the new
+     *  month and year. In that case, the day-of-month is adjusted to the maximum
+     *  valid value for the new month and year.
+     * <li>{@code YEARS} -
+     *  Returns a {@code LocalDate} with the specified number of years added.
+     *  This is equivalent to {@link #plusYears(long)}.
+     *  The day-of-month will be unchanged unless it would be invalid for the new
+     *  month and year. In that case, the day-of-month is adjusted to the maximum
+     *  valid value for the new month and year.
+     * <li>{@code DECADES} -
+     *  Returns a {@code LocalDate} with the specified number of decades added.
+     *  This is equivalent to calling {@link #plusYears(long)} with the amount
+     *  multiplied by 10.
+     *  The day-of-month will be unchanged unless it would be invalid for the new
+     *  month and year. In that case, the day-of-month is adjusted to the maximum
+     *  valid value for the new month and year.
+     * <li>{@code CENTURIES} -
+     *  Returns a {@code LocalDate} with the specified number of centuries added.
+     *  This is equivalent to calling {@link #plusYears(long)} with the amount
+     *  multiplied by 100.
+     *  The day-of-month will be unchanged unless it would be invalid for the new
+     *  month and year. In that case, the day-of-month is adjusted to the maximum
+     *  valid value for the new month and year.
+     * <li>{@code MILLENNIA} -
+     *  Returns a {@code LocalDate} with the specified number of millennia added.
+     *  This is equivalent to calling {@link #plusYears(long)} with the amount
+     *  multiplied by 1,000.
+     *  The day-of-month will be unchanged unless it would be invalid for the new
+     *  month and year. In that case, the day-of-month is adjusted to the maximum
+     *  valid value for the new month and year.
+     * <li>{@code ERAS} -
+     *  Returns a {@code LocalDate} with the specified number of eras added.
+     *  Only two eras are supported so the amount must be one, zero or minus one.
+     *  If the amount is non-zero then the year is changed such that the year-of-era
+     *  is unchanged.
+     *  The day-of-month will be unchanged unless it would be invalid for the new
+     *  month and year. In that case, the day-of-month is adjusted to the maximum
+     *  valid value for the new month and year.
+     * </ul>
+     * <p>
+     * All other {@code ChronoUnit} instances will throw a {@code DateTimeException}.
      * <p>
-     * This method returns a new date based on this date with the specified period added.
-     * This can be used to add any period that is defined by a unit, for example to add years, months or days.
-     * The unit is responsible for the details of the calculation, including the resolution
-     * of any edge cases in the calculation.
+     * 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 period to add, not null
-     * @return a {@code LocalDate} based on this date with the specified period added, not null
-     * @throws DateTimeException if the unit cannot be added to this type
+     * @param unit  the unit of the amount to add, not null
+     * @return a {@code LocalDate} based on this date with the specified amount added, not null
+     * @throws DateTimeException if the addition cannot be made
+     * @throws ArithmeticException if numeric overflow occurs
      */
     @Override
     public LocalDate plus(long amountToAdd, TemporalUnit unit) {
         if (unit instanceof ChronoUnit) {
             ChronoUnit f = (ChronoUnit) unit;

@@ -1112,11 +1166,11 @@
                 case MILLENNIA: return plusYears(Math.multiplyExact(amountToAdd, 1000));
                 case ERAS: return with(ERA, Math.addExact(getLong(ERA), amountToAdd));
             }
             throw new DateTimeException("Unsupported unit: " + unit.getName());
         }
-        return unit.doPlus(this, amountToAdd);
+        return unit.addTo(this, amountToAdd);
     }
 
     //-----------------------------------------------------------------------
     /**
      * Returns a copy of this {@code LocalDate} with the specified period in years added.

@@ -1219,44 +1273,51 @@
         return LocalDate.ofEpochDay(mjDay);
     }
 
     //-----------------------------------------------------------------------
     /**
-     * Returns a copy of this date with the specified period subtracted.
+     * Returns a copy of this date with the specified amount subtracted.
      * <p>
-     * This method returns a new date based on this date with the specified period subtracted.
-     * The subtractor is typically {@link Period} but may be any other type implementing
-     * the {@link TemporalSubtractor} interface.
-     * The calculation is delegated to the specified adjuster, which typically calls
-     * back to {@link #minus(long, TemporalUnit)}.
+     * This returns a {@code LocalDate}, based on this one, with the specified amount subtracted.
+     * The amount is typically {@link Period} 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 subtractor  the subtractor to use, not null
+     * @param amountToSubtract  the amount to subtract, not null
      * @return a {@code LocalDate} based on this date with the subtraction made, not null
      * @throws DateTimeException if the subtraction cannot be made
      * @throws ArithmeticException if numeric overflow occurs
      */
     @Override
-    public LocalDate minus(TemporalSubtractor subtractor) {
-        return (LocalDate) subtractor.subtractFrom(this);
+    public LocalDate minus(TemporalAmount amountToSubtract) {
+        return (LocalDate) amountToSubtract.subtractFrom(this);
     }
 
     /**
-     * Returns a copy of this date with the specified period subtracted.
+     * Returns a copy of this date with the specified amount subtracted.
+     * <p>
+     * This returns a {@code LocalDate}, 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 returns a new date based on this date with the specified period subtracted.
-     * This can be used to subtract any period that is defined by a unit, for example to subtract years, months or days.
-     * The unit is responsible for the details of the calculation, including the resolution
-     * of any edge cases in the calculation.
+     * 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 period to subtract, not null
-     * @return a {@code LocalDate} based on this date with the specified period subtracted, not null
-     * @throws DateTimeException if the unit cannot be added to this type
+     * @param unit  the unit of the amount to subtract, not null
+     * @return a {@code LocalDate} based on this date with the specified amount subtracted, not null
+     * @throws DateTimeException if the subtraction cannot be made
+     * @throws ArithmeticException if numeric overflow occurs
      */
     @Override
     public LocalDate minus(long amountToSubtract, TemporalUnit unit) {
         return (amountToSubtract == Long.MIN_VALUE ? plus(Long.MAX_VALUE, unit).plus(1, unit) : plus(-amountToSubtract, unit));
     }

@@ -1365,12 +1426,16 @@
      * @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)
      */
-    @Override  // override for Javadoc
+    @SuppressWarnings("unchecked")
+    @Override
     public <R> R query(TemporalQuery<R> query) {
+        if (query == Queries.localDate()) {
+            return (R) this;
+        }
         return ChronoLocalDate.super.query(query);
     }
 
     /**
      * Adjusts the specified temporal object to have the same date as this object.

@@ -1415,18 +1480,19 @@
      * The calculation returns a whole number, representing the number of
      * complete units between the two dates.
      * For example, the period in months between 2012-06-15 and 2012-08-14
      * will only be one month as it is one day short of two months.
      * <p>
-     * This method operates in association with {@link TemporalUnit#between}.
-     * The result of this method is a {@code long} representing the amount of
-     * the specified unit. By contrast, the result of {@code between} is an
-     * object that can be used directly in addition/subtraction:
+     * 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>
-     *   long period = start.periodUntil(end, MONTHS);   // this method
-     *   dateTime.plus(MONTHS.between(start, end));      // use in plus/minus
+     *   // these two lines are equivalent
+     *   amount = start.periodUntil(end, MONTHS);
+     *   amount = MONTHS.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 DAYS}, {@code WEEKS}, {@code MONTHS}, {@code YEARS},
      * {@code DECADES}, {@code CENTURIES}, {@code MILLENNIA} and {@code ERAS}
      * are supported. Other {@code ChronoUnit} values will throw an exception.

@@ -1462,11 +1528,11 @@
                 case MILLENNIA: return monthsUntil(end) / 12000;
                 case ERAS: return end.getLong(ERA) - getLong(ERA);
             }
             throw new DateTimeException("Unsupported unit: " + unit.getName());
         }
-        return unit.between(this, endDate).getAmount();
+        return unit.between(this, endDate);
     }
 
     long daysUntil(LocalDate end) {
         return end.toEpochDay() - toEpochDay();  // no overflow
     }

@@ -1475,35 +1541,85 @@
         long packed1 = getEpochMonth() * 32L + getDayOfMonth();  // no overflow
         long packed2 = end.getEpochMonth() * 32L + end.getDayOfMonth();  // no overflow
         return (packed2 - packed1) / 32;
     }
 
+    /**
+     * Calculates the period between this date and another date as a {@code Period}.
+     * <p>
+     * This calculates the period between two dates in terms of years, months and days.
+     * The start and end points are {@code this} and the specified date.
+     * The result will be negative if the end is before the start.
+     * <p>
+     * The calculation is performed using the ISO calendar system.
+     * If necessary, the input date will be converted to ISO.
+     * <p>
+     * The start date is included, but the end date is not.
+     * The period is calculated by removing complete months, then calculating
+     * the remaining number of days, adjusting to ensure that both have the same sign.
+     * The number of months is then normalized into years and months based on a 12 month year.
+     * A month is considered to be complete if the end day-of-month is greater
+     * than or equal to the start day-of-month.
+     * For example, from {@code 2010-01-15} to {@code 2011-03-18} is "1 year, 2 months and 3 days".
+     * <p>
+     * The result of this method can be a negative period if the end is before the start.
+     * The negative sign will be the same in each of year, month and day.
+     * <p>
+     * There are two equivalent ways of using this method.
+     * The first is to invoke this method.
+     * The second is to use {@link Period#between(LocalDate, LocalDate)}:
+     * <pre>
+     *   // these two lines are equivalent
+     *   period = start.periodUntil(end);
+     *   period = Period.between(start, end);
+     * </pre>
+     * The choice should be made based on which makes the code more readable.
+     *
+     * @param endDate  the end date, exclusive, which may be in any chronology, not null
+     * @return the period between this date and the end date, not null
+     */
+    @Override
+    public Period periodUntil(ChronoLocalDate<?> endDate) {
+        LocalDate end = LocalDate.from(endDate);
+        long totalMonths = end.getEpochMonth() - this.getEpochMonth();  // safe
+        int days = end.day - this.day;
+        if (totalMonths > 0 && days < 0) {
+            totalMonths--;
+            LocalDate calcDate = this.plusMonths(totalMonths);
+            days = (int) (end.toEpochDay() - calcDate.toEpochDay());  // safe
+        } else if (totalMonths < 0 && days > 0) {
+            totalMonths++;
+            days -= end.lengthOfMonth();
+        }
+        long years = totalMonths / 12;  // safe
+        int months = (int) (totalMonths % 12);  // safe
+        return Period.of(Math.toIntExact(years), months, days);
+    }
+
     //-----------------------------------------------------------------------
     /**
-     * Returns a local date-time formed from this date at the specified time.
+     * Combines this date with a time to create a {@code LocalDateTime}.
      * <p>
-     * This combines this date with the specified time to form a {@code LocalDateTime}.
+     * This returns a {@code LocalDateTime} formed from this date at the specified time.
      * All possible combinations of date and time are valid.
-     * <p>
-     * This instance is immutable and unaffected by this method call.
      *
      * @param time  the time to combine with, not null
      * @return the local date-time formed from this date and the specified time, not null
      */
     @Override
     public LocalDateTime atTime(LocalTime time) {
         return LocalDateTime.of(this, time);
     }
 
     /**
-     * Returns a local date-time formed from this date at the specified time.
+     * Combines this date with a time to create a {@code LocalDateTime}.
      * <p>
-     * This combines this date with the specified time to form a {@code LocalDateTime}.
+     * This returns a {@code LocalDateTime} formed from this date at the
+     * specified hour and minute.
+     * The seconds and nanosecond fields will be set to zero.
      * The individual time fields must be within their valid range.
      * All possible combinations of date and time are valid.
-     * <p>
-     * This instance is immutable and unaffected by this method call.
      *
      * @param hour  the hour-of-day to use, from 0 to 23
      * @param minute  the minute-of-hour to use, from 0 to 59
      * @return the local date-time formed from this date and the specified time, not null
      * @throws DateTimeException if the value of any field is out of range

@@ -1511,17 +1627,17 @@
     public LocalDateTime atTime(int hour, int minute) {
         return atTime(LocalTime.of(hour, minute));
     }
 
     /**
-     * Returns a local date-time formed from this date at the specified time.
+     * Combines this date with a time to create a {@code LocalDateTime}.
      * <p>
-     * This combines this date with the specified time to form a {@code LocalDateTime}.
+     * This returns a {@code LocalDateTime} formed from this date at the
+     * specified hour, minute and second.
+     * The nanosecond field will be set to zero.
      * The individual time fields must be within their valid range.
      * All possible combinations of date and time are valid.
-     * <p>
-     * This instance is immutable and unaffected by this method call.
      *
      * @param hour  the hour-of-day to use, from 0 to 23
      * @param minute  the minute-of-hour to use, from 0 to 59
      * @param second  the second-of-minute to represent, from 0 to 59
      * @return the local date-time formed from this date and the specified time, not null

@@ -1530,17 +1646,16 @@
     public LocalDateTime atTime(int hour, int minute, int second) {
         return atTime(LocalTime.of(hour, minute, second));
     }
 
     /**
-     * Returns a local date-time formed from this date at the specified time.
+     * Combines this date with a time to create a {@code LocalDateTime}.
      * <p>
-     * This combines this date with the specified time to form a {@code LocalDateTime}.
+     * This returns a {@code LocalDateTime} formed from this date at the
+     * specified hour, minute, second and nanosecond.
      * The individual time fields must be within their valid range.
      * All possible combinations of date and time are valid.
-     * <p>
-     * This instance is immutable and unaffected by this method call.
      *
      * @param hour  the hour-of-day to use, from 0 to 23
      * @param minute  the minute-of-hour to use, from 0 to 59
      * @param second  the second-of-minute to represent, from 0 to 59
      * @param nanoOfSecond  the nano-of-second to represent, from 0 to 999,999,999

@@ -1550,22 +1665,33 @@
     public LocalDateTime atTime(int hour, int minute, int second, int nanoOfSecond) {
         return atTime(LocalTime.of(hour, minute, second, nanoOfSecond));
     }
 
     /**
-     * Returns an offset date formed from this date and the specified offset.
+     * Combines this date with an offset time to create an {@code OffsetDateTime}.
      * <p>
-     * This combines this date with the specified offset to form an {@code OffsetDate}.
-     * All possible combinations of date and offset are valid.
+     * This returns an {@code OffsetDateTime} formed from this date at the specified time.
+     * All possible combinations of date and time are valid.
+     *
+     * @param time  the time to combine with, not null
+     * @return the offset date-time formed from this date and the specified time, not null
+     */
+    public OffsetDateTime atTime(OffsetTime time) {
+        return OffsetDateTime.of(LocalDateTime.of(this, time.toLocalTime()), time.getOffset());
+    }
+
+    /**
+     * Combines this date with the time of midnight to create a {@code LocalDateTime}
+     * at the start of this date.
      * <p>
-     * This instance is immutable and unaffected by this method call.
+     * This returns a {@code LocalDateTime} formed from this date at the time of
+     * midnight, 00:00, at the start of this date.
      *
-     * @param offset  the offset to combine with, not null
-     * @return the offset date formed from this date and the specified offset, not null
+     * @return the local date-time of midnight at the start of this date, not null
      */
-    public OffsetDate atOffset(ZoneOffset offset) {
-        return OffsetDate.of(this, offset);
+    public LocalDateTime atStartOfDay() {
+        return LocalDateTime.of(this, LocalTime.MIDNIGHT);
     }
 
     /**
      * Returns a zoned date-time from this date at the earliest valid time according
      * to the rules in the time-zone.

@@ -1580,12 +1706,10 @@
      * <p>
      * If the zone ID is a {@link ZoneOffset}, then the result always has a time of midnight.
      * <p>
      * To convert to a specific time in a given time-zone call {@link #atTime(LocalTime)}
      * followed by {@link LocalDateTime#atZone(ZoneId)}.
-     * <p>
-     * This instance is immutable and unaffected by this method call.
      *
      * @param zone  the zone ID to use, not null
      * @return the zoned date-time formed from this date and the earliest valid time for the zone, not null
      */
     public ZonedDateTime atStartOfDay(ZoneId zone) {

@@ -1634,11 +1758,11 @@
      * It is "consistent with equals", as defined by {@link Comparable}.
      * <p>
      * If all the dates being compared are instances of {@code LocalDate},
      * then the comparison will be entirely based on the date.
      * If some dates being compared are in different chronologies, then the
-     * chronology is also considered, see {@link java.time.temporal.ChronoLocalDate#compareTo}.
+     * chronology is also considered, see {@link java.time.chrono.ChronoLocalDate#compareTo}.
      *
      * @param other  the other date to compare to, not null
      * @return the comparator value, negative if less, positive if greater
      */
     @Override  // override for Javadoc and performance

@@ -1820,11 +1944,11 @@
 
     /**
      * Outputs this date as a {@code String} using the formatter.
      * <p>
      * This date will be passed to the formatter
-     * {@link DateTimeFormatter#print(TemporalAccessor) print method}.
+     * {@link DateTimeFormatter#format(TemporalAccessor) format method}.
      *
      * @param formatter  the formatter to use, not null
      * @return the formatted date string, not null
      * @throws DateTimeException if an error occurs during printing
      */