Half.java
/*
* Copyright (c) 2007-present, Stephen Colebourne & Michael Nascimento Santos
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
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* this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* * Neither the name of JSR-310 nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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package org.threeten.extra;
import static java.time.temporal.ChronoField.MONTH_OF_YEAR;
import static org.threeten.extra.TemporalFields.HALF_OF_YEAR;
import static org.threeten.extra.TemporalFields.HALF_YEARS;
import java.time.DateTimeException;
import java.time.LocalDate;
import java.time.Month;
import java.time.chrono.Chronology;
import java.time.chrono.IsoChronology;
import java.time.format.DateTimeFormatterBuilder;
import java.time.format.TextStyle;
import java.time.temporal.ChronoField;
import java.time.temporal.Temporal;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.TemporalAdjuster;
import java.time.temporal.TemporalField;
import java.time.temporal.TemporalQueries;
import java.time.temporal.TemporalQuery;
import java.time.temporal.UnsupportedTemporalTypeException;
import java.time.temporal.ValueRange;
import java.util.Locale;
/**
* A half-of-year, such as 'H2'.
* <p>
* {@code Half} is an enum representing the 2 halves of the year - H1 and H2.
* These are defined as January to June and July to December.
* <p>
* The {@code int} value follows the half, from 1 (H1) to 2 (H2).
* It is recommended that applications use the enum rather than the {@code int} value
* to ensure code clarity.
* <p>
* <b>Do not use {@code ordinal()} to obtain the numeric representation of {@code Half}.
* Use {@code getValue()} instead.</b>
*
* <h3>Implementation Requirements:</h3>
* This is an immutable and thread-safe enum.
*/
public enum Half implements TemporalAccessor, TemporalAdjuster {
/**
* The singleton instance for the first half-of-year, from January to June.
* This has the numeric value of {@code 1}.
*/
H1,
/**
* The singleton instance for the second half-of-year, from July to December.
* This has the numeric value of {@code 2}.
*/
H2;
//-----------------------------------------------------------------------
/**
* Obtains an instance of {@code Half} from an {@code int} value.
* <p>
* {@code Half} is an enum representing the 2 halves of the year.
* This factory allows the enum to be obtained from the {@code int} value.
* The {@code int} value follows the half, from 1 (H1) to 2 (H2).
*
* @param halfOfYear the half-of-year to represent, from 1 (H1) to 2 (H2)
* @return the half-of-year, not null
* @throws DateTimeException if the half-of-year is invalid
*/
public static Half of(int halfOfYear) {
switch (halfOfYear) {
case 1:
return H1;
case 2:
return H2;
default:
throw new DateTimeException("Invalid value for Half: " + halfOfYear);
}
}
/**
* Obtains an instance of {@code Half} from a month-of-year.
* <p>
* {@code Half} is an enum representing the 2 halves of the year.
* This factory allows the enum to be obtained from the {@code Month} value.
* <p>
* January to June are H1 and July to December are H2.
*
* @param monthOfYear the month-of-year to convert from, from 1 to 12
* @return the half-of-year, not null
* @throws DateTimeException if the month-of-year is invalid
*/
public static Half ofMonth(int monthOfYear) {
MONTH_OF_YEAR.range().checkValidValue(monthOfYear, MONTH_OF_YEAR);
return of(monthOfYear <= 6 ? 1 : 2);
}
//-----------------------------------------------------------------------
/**
* Obtains an instance of {@code Half} from a temporal object.
* <p>
* This obtains a half 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 Half}.
* <p>
* The conversion extracts the {@link TemporalFields#HALF_OF_YEAR HALF_OF_YEAR} field.
* The extraction is only permitted if the temporal object has an ISO
* chronology, or can be converted to a {@code LocalDate}.
* <p>
* This method matches the signature of the functional interface {@link TemporalQuery}
* allowing it to be used in queries via method reference, {@code Half::from}.
*
* @param temporal the temporal-time object to convert, not null
* @return the half-of-year, not null
* @throws DateTimeException if unable to convert to a {@code Half}
*/
public static Half from(TemporalAccessor temporal) {
if (temporal instanceof Half) {
return (Half) temporal;
} else if (temporal instanceof Month) {
Month month = (Month) temporal;
return of(month.ordinal() / 6 + 1);
}
try {
TemporalAccessor adjusted =
!IsoChronology.INSTANCE.equals(Chronology.from(temporal)) ? LocalDate.from(temporal) : temporal;
// need to use getLong() as JDK Parsed class get() doesn't work properly
int qoy = Math.toIntExact(adjusted.getLong(HALF_OF_YEAR));
return of(qoy);
} catch (DateTimeException ex) {
throw new DateTimeException("Unable to obtain Half from TemporalAccessor: " +
temporal + " of type " + temporal.getClass().getName(), ex);
}
}
//-----------------------------------------------------------------------
/**
* Gets the half-of-year {@code int} value.
* <p>
* The values are numbered following the ISO-8601 standard,
* from 1 (H1) to 2 (H2).
*
* @return the half-of-year, from 1 (H1) to 2 (H2)
*/
public int getValue() {
return ordinal() + 1;
}
//-----------------------------------------------------------------------
/**
* Gets the textual representation, such as 'H1' or '4th half'.
* <p>
* This returns the textual name used to identify the half-of-year,
* suitable for presentation to the user.
* The parameters control the style of the returned text and the locale.
* <p>
* If no textual mapping is found then the {@link #getValue() numeric value} is returned.
*
* @param style the length of the text required, not null
* @param locale the locale to use, not null
* @return the text value of the half-of-year, not null
*/
public String getDisplayName(TextStyle style, Locale locale) {
return new DateTimeFormatterBuilder().appendText(HALF_OF_YEAR, style).toFormatter(locale).format(this);
}
//-----------------------------------------------------------------------
/**
* Checks if the specified field is supported.
* <p>
* This checks if this half-of-year 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 {@link TemporalFields#HALF_OF_YEAR HALF_OF_YEAR} then
* this method returns true.
* All {@code ChronoField} instances will return false.
* <p>
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
* passing {@code this} as the argument.
* Whether the field is supported is determined by the field.
*
* @param field the field to check, null returns false
* @return true if the field is supported on this half-of-year, false if not
*/
@Override
public boolean isSupported(TemporalField field) {
if (field == HALF_OF_YEAR) {
return true;
} else if (field instanceof ChronoField) {
return false;
}
return field != null && field.isSupportedBy(this);
}
/**
* Gets the range of valid values for the specified field.
* <p>
* The range object expresses the minimum and maximum valid values for a field.
* This half is used to enhance the accuracy of the returned range.
* If it is not possible to return the range, because the field is not supported
* or for some other reason, an exception is thrown.
* <p>
* If the field is {@link TemporalFields#HALF_OF_YEAR HALF_OF_YEAR} then the
* range of the half-of-year, from 1 to 2, will be returned.
* All {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
* <p>
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
* passing {@code this} as the argument.
* Whether the range can be obtained is determined by the field.
*
* @param field the field to query the range for, not null
* @return the range of valid values for the field, not null
* @throws DateTimeException if the range for the field cannot be obtained
* @throws UnsupportedTemporalTypeException if the field is not supported
*/
@Override
public ValueRange range(TemporalField field) {
if (field == HALF_OF_YEAR) {
return field.range();
} else if (field instanceof ChronoField) {
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
}
return TemporalAccessor.super.range(field);
}
/**
* Gets the value of the specified field from this half-of-year as an {@code int}.
* <p>
* This queries this half 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.
* <p>
* If the field is {@link TemporalFields#HALF_OF_YEAR HALF_OF_YEAR} then the
* value of the half-of-year, from 1 to 2, will be returned.
* All {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
* <p>
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
* passing {@code this} as the argument. Whether the value can be obtained,
* and what the value represents, is determined by the field.
*
* @param field the field to get, not null
* @return the value for the field, within the valid range of values
* @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
public int get(TemporalField field) {
if (field == HALF_OF_YEAR) {
return getValue();
} else if (field instanceof ChronoField) {
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
}
return TemporalAccessor.super.get(field);
}
/**
* Gets the value of the specified field from this half-of-year as a {@code long}.
* <p>
* This queries this half 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.
* <p>
* If the field is {@link TemporalFields#HALF_OF_YEAR HALF_OF_YEAR} then the
* value of the half-of-year, from 1 to 2, will be returned.
* All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
* <p>
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
* passing {@code this} as the argument. Whether the value can be obtained,
* and what the value represents, is determined by the field.
*
* @param field the field to get, not null
* @return the value for the field
* @throws DateTimeException if a value for the field cannot be obtained
* @throws UnsupportedTemporalTypeException if the field is not supported
* @throws ArithmeticException if numeric overflow occurs
*/
@Override
public long getLong(TemporalField field) {
if (field == HALF_OF_YEAR) {
return getValue();
} else if (field instanceof ChronoField) {
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
}
return field.getFrom(this);
}
//-----------------------------------------------------------------------
/**
* Returns the half that is the specified number of halves after this one.
* <p>
* The calculation rolls around the end of the year from H2 to H1.
* The specified period may be negative.
* <p>
* This instance is immutable and unaffected by this method call.
*
* @param halves the halves to add, positive or negative
* @return the resulting half, not null
*/
public Half plus(long halves) {
int amount = (int) halves % 2;
return values()[(ordinal() + (amount + 2)) % 2];
}
/**
* Returns the half that is the specified number of halves before this one.
* <p>
* The calculation rolls around the start of the year from H1 to H2.
* The specified period may be negative.
* <p>
* This instance is immutable and unaffected by this method call.
*
* @param halves the halves to subtract, positive or negative
* @return the resulting half, not null
*/
public Half minus(long halves) {
return plus(-(halves % 2));
}
//-----------------------------------------------------------------------
/**
* Gets the length of this half in days.
* <p>
* This takes a flag to determine whether to return the length for a leap year or not.
* <p>
* H1 has 181 in a standard year and 182 days in a leap year.
* H2 has 184 days.
*
* @param leapYear true if the length is required for a leap year
* @return the length of this month in days, 181, 182 or 184
*/
public int length(boolean leapYear) {
return this == H1 ? (leapYear ? 182 : 181) : 184;
}
//-----------------------------------------------------------------------
/**
* Gets the first of the six months that this half refers to.
* <p>
* H1 will return January.<br>
* H2 will return July.
*
* @return the first month in the half, not null
*/
public Month firstMonth() {
return this == H1 ? Month.JANUARY : Month.JULY;
}
//-----------------------------------------------------------------------
/**
* Queries this half-of-year using the specified query.
* <p>
* This queries this half-of-year using the specified query strategy object.
* The {@code TemporalQuery} object defines the logic to be used to
* obtain the result. Read the documentation of the query to understand
* what the result of this method will be.
* <p>
* The result of this method is obtained by invoking the
* {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
* specified query passing {@code this} as the argument.
*
* @param <R> the type of the result
* @param query the query to invoke, not null
* @return the query result, null may be returned (defined by the query)
* @throws DateTimeException if unable to query (defined by the query)
* @throws ArithmeticException if numeric overflow occurs (defined by the query)
*/
@SuppressWarnings("unchecked")
@Override
public <R> R query(TemporalQuery<R> query) {
if (query == TemporalQueries.chronology()) {
return (R) IsoChronology.INSTANCE;
} else if (query == TemporalQueries.precision()) {
return (R) HALF_YEARS;
}
return TemporalAccessor.super.query(query);
}
/**
* Adjusts the specified temporal object to have this half-of-year.
* <p>
* This returns a temporal object of the same observable type as the input
* with the half-of-year changed to be the same as this.
* <p>
* The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
* passing {@link TemporalFields#HALF_OF_YEAR} as the field.
* If the specified temporal object does not use the ISO calendar system then
* a {@code DateTimeException} is thrown.
* <p>
* In most cases, it is clearer to reverse the calling pattern by using
* {@link Temporal#with(TemporalAdjuster)}:
* <pre>
* // these two lines are equivalent, but the second approach is recommended
* temporal = thisHalf.adjustInto(temporal);
* temporal = temporal.with(thisHalf);
* </pre>
* <p>
* For example, given a date in May, the following are output:
* <pre>
* dateInMay.with(H1); // no change
* dateInMay.with(H2); // six months later
* </pre>
* <p>
* This instance is immutable and unaffected by this method call.
*
* @param temporal the target object to be adjusted, not null
* @return the adjusted object, not null
* @throws DateTimeException if unable to make the adjustment
* @throws ArithmeticException if numeric overflow occurs
*/
@Override
public Temporal adjustInto(Temporal temporal) {
if (Chronology.from(temporal).equals(IsoChronology.INSTANCE) == false) {
throw new DateTimeException("Adjustment only supported on ISO date-time");
}
return temporal.with(HALF_OF_YEAR, getValue());
}
}