* {@code MonthDay} is an immutable date-time object that represents the combination * of a year and month. Any field that can be derived from a month and day, such as * quarter-of-year, can be obtained. *

* This class does not store or represent a year, time or time-zone. * For example, the value "December 3rd" can be stored in a {@code MonthDay}. *

* Since a {@code MonthDay} does not possess a year, the leap day of * February 29th is considered valid. *

* This class implements {@link TemporalAccessor} rather than {@link Temporal}. * This is because it is not possible to define whether February 29th is valid or not * without external information, preventing the implementation of plus/minus. * Related to this, {@code MonthDay} only provides access to query and set the fields * {@code MONTH_OF_YEAR} and {@code DAY_OF_MONTH}. *

* 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 today's rules for leap years are applied for all time. * For most applications written today, the ISO-8601 rules are entirely suitable. * However, any application that makes use of historical dates, and requires them * to be accurate will find the ISO-8601 approach unsuitable. * *

* This is a value-based * class; use of identity-sensitive operations (including reference equality * ({@code ==}), identity hash code, or synchronization) on instances of * {@code MonthDay} 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 MonthDay implements TemporalAccessor, TemporalAdjuster, Comparable, Serializable { /** * Serialization version. */ private static final long serialVersionUID = -939150713474957432L; /** * Parser. */ private static final DateTimeFormatter PARSER = new DateTimeFormatterBuilder() .appendLiteral("--") .appendValue(MONTH_OF_YEAR, 2) .appendLiteral('-') .appendValue(DAY_OF_MONTH, 2) .toFormatter(); /** * The month-of-year, not null. */ private final int month; /** * The day-of-month. */ private final int day; //----------------------------------------------------------------------- /** * Obtains the current month-day from the system clock in the default time-zone. *

* This will query the {@link java.time.Clock#systemDefaultZone() system clock} in the default * time-zone to obtain the current month-day. *

* Using this method will prevent the ability to use an alternate clock for testing * because the clock is hard-coded. * * @return the current month-day using the system clock and default time-zone, not null */ public static MonthDay now() { return now(Clock.systemDefaultZone()); } /** * Obtains the current month-day from the system clock in the specified time-zone. *

* This will query the {@link Clock#system(java.time.ZoneId) system clock} to obtain the current month-day. * Specifying the time-zone avoids dependence on the default time-zone. *

* Using this method will prevent the ability to use an alternate clock for testing * because the clock is hard-coded. * * @param zone the zone ID to use, not null * @return the current month-day using the system clock, not null */ public static MonthDay now(ZoneId zone) { return now(Clock.system(zone)); } /** * Obtains the current month-day from the specified clock. *

* This will query the specified clock to obtain the current month-day. * 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 month-day, not null */ public static MonthDay now(Clock clock) { final LocalDate now = LocalDate.now(clock); // called once return MonthDay.of(now.getMonth(), now.getDayOfMonth()); } //----------------------------------------------------------------------- /** * Obtains an instance of {@code MonthDay}. *

* The day-of-month must be valid for the month within a leap year. * Hence, for February, day 29 is valid. *

* For example, passing in April and day 31 will throw an exception, as * there can never be April 31st in any year. By contrast, passing in * February 29th is permitted, as that month-day can sometimes be valid. * * @param month the month-of-year to represent, not null * @param dayOfMonth the day-of-month to represent, from 1 to 31 * @return the month-day, not null * @throws DateTimeException if the value of any field is out of range, * or if the day-of-month is invalid for the month */ public static MonthDay of(Month month, int dayOfMonth) { Objects.requireNonNull(month, "month"); DAY_OF_MONTH.checkValidValue(dayOfMonth); if (dayOfMonth > month.maxLength()) { throw new DateTimeException("Illegal value for DayOfMonth field, value " + dayOfMonth + " is not valid for month " + month.name()); } return new MonthDay(month.getValue(), dayOfMonth); } /** * Obtains an instance of {@code MonthDay}. *

* The day-of-month must be valid for the month within a leap year. * Hence, for month 2 (February), day 29 is valid. *

* For example, passing in month 4 (April) and day 31 will throw an exception, as * there can never be April 31st in any year. By contrast, passing in * February 29th is permitted, as that month-day can sometimes be valid. * * @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 month-day, not null * @throws DateTimeException if the value of any field is out of range, * or if the day-of-month is invalid for the month */ public static MonthDay of(int month, int dayOfMonth) { return of(Month.of(month), dayOfMonth); } //----------------------------------------------------------------------- /** * Obtains an instance of {@code MonthDay} from a temporal object. *

* This obtains a month-day 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 MonthDay}. *

* The conversion extracts the {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} and * {@link ChronoField#DAY_OF_MONTH DAY_OF_MONTH} fields. * The extraction is only permitted if the temporal object has an ISO * chronology, or can be converted to a {@code LocalDate}. *

* This method matches the signature of the functional interface {@link TemporalQuery} * allowing it to be used in queries via method reference, {@code MonthDay::from}. * * @param temporal the temporal object to convert, not null * @return the month-day, not null * @throws DateTimeException if unable to convert to a {@code MonthDay} */ public static MonthDay from(TemporalAccessor temporal) { if (temporal instanceof MonthDay) { return (MonthDay) temporal; } try { if (IsoChronology.INSTANCE.equals(Chronology.from(temporal)) == false) { temporal = LocalDate.from(temporal); } return of(temporal.get(MONTH_OF_YEAR), temporal.get(DAY_OF_MONTH)); } catch (DateTimeException ex) { throw new DateTimeException("Unable to obtain MonthDay from TemporalAccessor: " + temporal + " of type " + temporal.getClass().getName(), ex); } } //----------------------------------------------------------------------- /** * Obtains an instance of {@code MonthDay} from a text string such as {@code --12-03}. *

* The string must represent a valid month-day. * The format is {@code --MM-dd}. * * @param text the text to parse such as "--12-03", not null * @return the parsed month-day, not null * @throws DateTimeParseException if the text cannot be parsed */ public static MonthDay parse(CharSequence text) { return parse(text, PARSER); } /** * Obtains an instance of {@code MonthDay} from a text string using a specific formatter. *

* The text is parsed using the formatter, returning a month-day. * * @param text the text to parse, not null * @param formatter the formatter to use, not null * @return the parsed month-day, not null * @throws DateTimeParseException if the text cannot be parsed */ public static MonthDay parse(CharSequence text, DateTimeFormatter formatter) { Objects.requireNonNull(formatter, "formatter"); return formatter.parse(text, MonthDay::from); } //----------------------------------------------------------------------- /** * Constructor, previously validated. * * @param month the month-of-year to represent, validated from 1 to 12 * @param dayOfMonth the day-of-month to represent, validated from 1 to 29-31 */ private MonthDay(int month, int dayOfMonth) { this.month = month; this.day = dayOfMonth; } //----------------------------------------------------------------------- /** * Checks if the specified field is supported. *

* This checks if this month-day 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. *

* If the field is a {@link ChronoField} then the query is implemented here. * The supported fields are: *

*
• {@code MONTH_OF_YEAR} *
• {@code YEAR} *

* 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 month-day, false if not */ @Override public boolean isSupported(TemporalField field) { if (field instanceof ChronoField) { return field == MONTH_OF_YEAR || field == DAY_OF_MONTH; } return field != null && field.isSupportedBy(this); } /** * Gets the range of valid values for the specified field. *

* The range object expresses the minimum and maximum valid values for a field. * This month-day 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. *

* 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}. *

* 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 public ValueRange range(TemporalField field) { if (field == MONTH_OF_YEAR) { return field.range(); } else if (field == DAY_OF_MONTH) { return ValueRange.of(1, getMonth().minLength(), getMonth().maxLength()); } return TemporalAccessor.super.range(field); } /** * Gets the value of the specified field from this month-day as an {@code int}. *

* This queries this month-day for the value for 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. *

* 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 month-day. * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}. *

* 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 public int get(TemporalField field) { return range(field).checkValidIntValue(getLong(field), field); } /** * Gets the value of the specified field from this month-day as a {@code long}. *

* This queries this month-day for the value for 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. *

* 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 month-day. * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}. *

* 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) { // alignedDOW and alignedWOM not supported because they cannot be set in with() case DAY_OF_MONTH: return day; case MONTH_OF_YEAR: return month; } throw new UnsupportedTemporalTypeException("Unsupported field: " + field); } return field.getFrom(this); } //----------------------------------------------------------------------- /** * Gets the month-of-year field from 1 to 12. *

* This method returns the month as an {@code int} from 1 to 12. * Application code is frequently clearer if the enum {@link Month} * is used by calling {@link #getMonth()}. * * @return the month-of-year, from 1 to 12 * @see #getMonth() */ public int getMonthValue() { return month; } /** * Gets the month-of-year field using the {@code Month} enum. *

* This method returns the enum {@link Month} for the month. * This avoids confusion as to what {@code int} values mean. * If you need access to the primitive {@code int} value then the enum * provides the {@link Month#getValue() int value}. * * @return the month-of-year, not null * @see #getMonthValue() */ public Month getMonth() { return Month.of(month); } /** * Gets the day-of-month field. *

* This method returns the primitive {@code int} value for the day-of-month. * * @return the day-of-month, from 1 to 31 */ public int getDayOfMonth() { return day; } //----------------------------------------------------------------------- /** * Checks if the year is valid for this month-day. *

* This method checks whether this month and day and the input year form * a valid date. This can only return false for February 29th. * * @param year the year to validate, an out of range value returns false * @return true if the year is valid for this month-day * @see Year#isValidMonthDay(MonthDay) */ public boolean isValidYear(int year) { return (day == 29 && month == 2 && Year.isLeap(year) == false) == false; } //----------------------------------------------------------------------- /** * Returns a copy of this {@code MonthDay} with the month-of-year altered. *

* This returns a month-day with the specified month. * If the day-of-month is invalid for the specified month, the day will * be adjusted to the last valid day-of-month. *

* This instance is immutable and unaffected by this method call. * * @param month the month-of-year to set in the returned month-day, from 1 (January) to 12 (December) * @return a {@code MonthDay} based on this month-day with the requested month, not null * @throws DateTimeException if the month-of-year value is invalid */ public MonthDay withMonth(int month) { return with(Month.of(month)); } /** * Returns a copy of this {@code MonthDay} with the month-of-year altered. *

* This returns a month-day with the specified month. * If the day-of-month is invalid for the specified month, the day will * be adjusted to the last valid day-of-month. *

* This instance is immutable and unaffected by this method call. * * @param month the month-of-year to set in the returned month-day, not null * @return a {@code MonthDay} based on this month-day with the requested month, not null */ public MonthDay with(Month month) { Objects.requireNonNull(month, "month"); if (month.getValue() == this.month) { return this; } int day = Math.min(this.day, month.maxLength()); return new MonthDay(month.getValue(), day); } /** * Returns a copy of this {@code MonthDay} with the day-of-month altered. *

* This returns a month-day with the specified day-of-month. * If the day-of-month is invalid for the month, an exception is thrown. *

* This instance is immutable and unaffected by this method call. * * @param dayOfMonth the day-of-month to set in the return month-day, from 1 to 31 * @return a {@code MonthDay} based on this month-day with the requested day, not null * @throws DateTimeException if the day-of-month value is invalid, * or if the day-of-month is invalid for the month */ public MonthDay withDayOfMonth(int dayOfMonth) { if (dayOfMonth == this.day) { return this; } return of(month, dayOfMonth); } //----------------------------------------------------------------------- /** * Queries this month-day using the specified query. *

* This queries this month-day 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. *

* 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 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 query(TemporalQuery query) { if (query == TemporalQueries.chronology()) { return (R) IsoChronology.INSTANCE; } return TemporalAccessor.super.query(query); } /** * Adjusts the specified temporal object to have this month-day. *

* This returns a temporal object of the same observable type as the input * with the month and day-of-month changed to be the same as this. *

* The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)} * twice, passing {@link ChronoField#MONTH_OF_YEAR} and * {@link ChronoField#DAY_OF_MONTH} as the fields. * If the specified temporal object does not use the ISO calendar system then * a {@code DateTimeException} is thrown. *

* In most cases, it is clearer to reverse the calling pattern by using * {@link Temporal#with(TemporalAdjuster)}: *

     *   // these two lines are equivalent, but the second approach is recommended
     *   temporal = thisMonthDay.adjustInto(temporal);
     *   temporal = temporal.with(thisMonthDay);
     * 

* 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) { if (Chronology.from(temporal).equals(IsoChronology.INSTANCE) == false) { throw new DateTimeException("Adjustment only supported on ISO date-time"); } temporal = temporal.with(MONTH_OF_YEAR, month); return temporal.with(DAY_OF_MONTH, Math.min(temporal.range(DAY_OF_MONTH).getMaximum(), day)); } /** * Formats this month-day using the specified formatter. *

* This month-day will be passed to the formatter to produce a string. * * @param formatter the formatter to use, not null * @return the formatted month-day string, not null * @throws DateTimeException if an error occurs during printing */ public String format(DateTimeFormatter formatter) { Objects.requireNonNull(formatter, "formatter"); return formatter.format(this); } //----------------------------------------------------------------------- /** * Combines this month-day with a year to create a {@code LocalDate}. *

* This returns a {@code LocalDate} formed from this month-day and the specified year. *

* A month-day of February 29th will be adjusted to February 28th in the resulting * date if the year is not a leap year. *

* This instance is immutable and unaffected by this method call. * * @param year the year to use, from MIN_YEAR to MAX_YEAR * @return the local date formed from this month-day and the specified year, not null * @throws DateTimeException if the year is outside the valid range of years */ public LocalDate atYear(int year) { return LocalDate.of(year, month, isValidYear(year) ? day : 28); } //----------------------------------------------------------------------- /** * Compares this month-day to another month-day. *

* The comparison is based first on value of the month, then on the value of the day. * It is "consistent with equals", as defined by {@link Comparable}. * * @param other the other month-day to compare to, not null * @return the comparator value, negative if less, positive if greater */ @Override public int compareTo(MonthDay other) { int cmp = (month - other.month); if (cmp == 0) { cmp = (day - other.day); } return cmp; } /** * Is this month-day after the specified month-day. * * @param other the other month-day to compare to, not null * @return true if this is after the specified month-day */ public boolean isAfter(MonthDay other) { return compareTo(other) > 0; } /** * Is this month-day before the specified month-day. * * @param other the other month-day to compare to, not null * @return true if this point is before the specified month-day */ public boolean isBefore(MonthDay other) { return compareTo(other) < 0; } //----------------------------------------------------------------------- /** * Checks if this month-day is equal to another month-day. *

* The comparison is based on the time-line position of the month-day within a year. * * @param obj the object to check, null returns false * @return true if this is equal to the other month-day */ @Override public boolean equals(Object obj) { if (this == obj) { return true; } if (obj instanceof MonthDay) { MonthDay other = (MonthDay) obj; return month == other.month && day == other.day; } return false; } /** * A hash code for this month-day. * * @return a suitable hash code */ @Override public int hashCode() { return (month << 6) + day; } //----------------------------------------------------------------------- /** * Outputs this month-day as a {@code String}, such as {@code --12-03}. *

* The output will be in the format {@code --MM-dd}: * * @return a string representation of this month-day, not null */ @Override public String toString() { return new StringBuilder(10).append("--") .append(month < 10 ? "0" : "").append(month) .append(day < 10 ? "-0" : "-").append(day) .toString(); } //----------------------------------------------------------------------- /** * Writes the object using a * dedicated serialized form. * @serialData *

     *  out.writeByte(13);  // identifies a MonthDay
     *  out.writeByte(month);
     *  out.writeByte(day);
     *