* {@code MonthDay} is an immutable date-time object that represents the combination * of a month and day-of-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
* This will query the {@link 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(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 as a query 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:
*
* 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 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.
*
* 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 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.
*
* 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
* @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
* 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)}:
*
* 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;
}
/**
* Checks if this month-day is 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;
}
/**
* Checks if this month-day is 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
*
*
* All other {@code ChronoField} instances will return false.
*
* // these two lines are equivalent, but the second approach is recommended
* temporal = thisMonthDay.adjustInto(temporal);
* temporal = temporal.with(thisMonthDay);
*
*
* out.writeByte(13); // identifies a MonthDay
* out.writeByte(month);
* out.writeByte(day);
*
*
* @return the instance of {@code Ser}, not null
*/
@java.io.Serial
private Object writeReplace() {
return new Ser(Ser.MONTH_DAY_TYPE, this);
}
/**
* Defend against malicious streams.
*
* @param s the stream to read
* @throws InvalidObjectException always
*/
@java.io.Serial
private void readObject(ObjectInputStream s) throws InvalidObjectException {
throw new InvalidObjectException("Deserialization via serialization delegate");
}
void writeExternal(DataOutput out) throws IOException {
out.writeByte(month);
out.writeByte(day);
}
static MonthDay readExternal(DataInput in) throws IOException {
byte month = in.readByte();
byte day = in.readByte();
return MonthDay.of(month, day);
}
}