JDK8/Java8源码在线阅读
/*
* Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* This file is available under and governed by the GNU General Public
* License version 2 only, as published by the Free Software Foundation.
* However, the following notice accompanied the original version of this
* file:
*
* Copyright (c) 2007-2012, Stephen Colebourne & Michael Nascimento Santos
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* * Neither the name of JSR-310 nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package java.time;
import static java.time.temporal.ChronoField.MONTH_OF_YEAR;
import static java.time.temporal.ChronoUnit.MONTHS;
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 month-of-year, such as 'July'.
* <p>
* {@code Month} is an enum representing the 12 months of the year -
* January, February, March, April, May, June, July, August, September, October,
* November and December.
* <p>
* In addition to the textual enum name, each month-of-year has an {@code int} value.
* The {@code int} value follows normal usage and the ISO-8601 standard,
* from 1 (January) to 12 (December). 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 Month}.
* Use {@code getValue()} instead.</b>
* <p>
* This enum represents a common concept that is found in many calendar systems.
* As such, this enum may be used by any calendar system that has the month-of-year
* concept defined exactly equivalent to the ISO-8601 calendar system.
*
* @implSpec
* This is an immutable and thread-safe enum.
*
* @since 1.8
*/
public enum Month implements TemporalAccessor, TemporalAdjuster {
/**
* The singleton instance for the month of January with 31 days.
* This has the numeric value of {@code 1}.
*/
JANUARY,
/**
* The singleton instance for the month of February with 28 days, or 29 in a leap year.
* This has the numeric value of {@code 2}.
*/
FEBRUARY,
/**
* The singleton instance for the month of March with 31 days.
* This has the numeric value of {@code 3}.
*/
MARCH,
/**
* The singleton instance for the month of April with 30 days.
* This has the numeric value of {@code 4}.
*/
APRIL,
/**
* The singleton instance for the month of May with 31 days.
* This has the numeric value of {@code 5}.
*/
MAY,
/**
* The singleton instance for the month of June with 30 days.
* This has the numeric value of {@code 6}.
*/
JUNE,
/**
* The singleton instance for the month of July with 31 days.
* This has the numeric value of {@code 7}.
*/
JULY,
/**
* The singleton instance for the month of August with 31 days.
* This has the numeric value of {@code 8}.
*/
AUGUST,
/**
* The singleton instance for the month of September with 30 days.
* This has the numeric value of {@code 9}.
*/
SEPTEMBER,
/**
* The singleton instance for the month of October with 31 days.
* This has the numeric value of {@code 10}.
*/
OCTOBER,
/**
* The singleton instance for the month of November with 30 days.
* This has the numeric value of {@code 11}.
*/
NOVEMBER,
/**
* The singleton instance for the month of December with 31 days.
* This has the numeric value of {@code 12}.
*/
DECEMBER;
/**
* Private cache of all the constants.
*/
private static final Month[] ENUMS = Month.values();
//-----------------------------------------------------------------------
/**
* Obtains an instance of {@code Month} from an {@code int} value.
* <p>
* {@code Month} is an enum representing the 12 months of the year.
* This factory allows the enum to be obtained from the {@code int} value.
* The {@code int} value follows the ISO-8601 standard, from 1 (January) to 12 (December).
*
* @param month the month-of-year to represent, from 1 (January) to 12 (December)
* @return the month-of-year, not null
* @throws DateTimeException if the month-of-year is invalid
*/
public static Month of(int month) {
if (month < 1 || month > 12) {
throw new DateTimeException("Invalid value for MonthOfYear: " + month);
}
return ENUMS[month - 1];
}
//-----------------------------------------------------------------------
/**
* Obtains an instance of {@code Month} from a temporal object.
* <p>
* This obtains a month 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 Month}.
* <p>
* The conversion extracts the {@link ChronoField#MONTH_OF_YEAR MONTH_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 Month::from}.
*
* @param temporal the temporal object to convert, not null
* @return the month-of-year, not null
* @throws DateTimeException if unable to convert to a {@code Month}
*/
public static Month from(TemporalAccessor temporal) {
if (temporal instanceof Month) {
return (Month) temporal;
}
try {
if (IsoChronology.INSTANCE.equals(Chronology.from(temporal)) == false) {
temporal = LocalDate.from(temporal);
}
return of(temporal.get(MONTH_OF_YEAR));
} catch (DateTimeException ex) {
throw new DateTimeException("Unable to obtain Month from TemporalAccessor: " +
temporal + " of type " + temporal.getClass().getName(), ex);
}
}
//-----------------------------------------------------------------------
/**
* Gets the month-of-year {@code int} value.
* <p>
* The values are numbered following the ISO-8601 standard,
* from 1 (January) to 12 (December).
*
* @return the month-of-year, from 1 (January) to 12 (December)
*/
public int getValue() {
return ordinal() + 1;
}
//-----------------------------------------------------------------------
/**
* Gets the textual representation, such as 'Jan' or 'December'.
* <p>
* This returns the textual name used to identify the month-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 month-of-year, not null
*/
public String getDisplayName(TextStyle style, Locale locale) {
return new DateTimeFormatterBuilder().appendText(MONTH_OF_YEAR, style).toFormatter(locale).format(this);
}
//-----------------------------------------------------------------------
/**
* Checks if the specified field is supported.
* <p>
* This checks if this month-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 ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then
* this method returns true.
* All other {@code ChronoField} instances will return false.
* <p>
* If the field is not a {@code ChronoField}, then the result of this method
* is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
* passing {@code this} as the argument.
* Whether the field is supported is determined by the field.
*
* @param field the field to check, null returns false
* @return true if the field is supported on this month-of-year, false if not
*/
@Override
public boolean isSupported(TemporalField field) {
if (field instanceof ChronoField) {
return field == MONTH_OF_YEAR;
}
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 month 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 ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then the
* range of the month-of-year, from 1 to 12, 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.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();
}
return TemporalAccessor.super.range(field);
}
/**
* Gets the value of the specified field from this month-of-year as an {@code int}.
* <p>
* This queries this month 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 ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then the
* value of the month-of-year, from 1 to 12, 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, 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 == MONTH_OF_YEAR) {
return getValue();
}
return TemporalAccessor.super.get(field);
}
/**
* Gets the value of the specified field from this month-of-year as a {@code long}.
* <p>
* This queries this month 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 ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} then the
* value of the month-of-year, from 1 to 12, 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 == MONTH_OF_YEAR) {
return getValue();
} else if (field instanceof ChronoField) {
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
}
return field.getFrom(this);
}
//-----------------------------------------------------------------------
/**
* Returns the month-of-year that is the specified number of quarters after this one.
* <p>
* The calculation rolls around the end of the year from December to January.
* The specified period may be negative.
* <p>
* This instance is immutable and unaffected by this method call.
*
* @param months the months to add, positive or negative
* @return the resulting month, not null
*/
public Month plus(long months) {
int amount = (int) (months % 12);
return ENUMS[(ordinal() + (amount + 12)) % 12];
}
/**
* Returns the month-of-year that is the specified number of months before this one.
* <p>
* The calculation rolls around the start of the year from January to December.
* The specified period may be negative.
* <p>
* This instance is immutable and unaffected by this method call.
*
* @param months the months to subtract, positive or negative
* @return the resulting month, not null
*/
public Month minus(long months) {
return plus(-(months % 12));
}
//-----------------------------------------------------------------------
/**
* Gets the length of this month in days.
* <p>
* This takes a flag to determine whether to return the length for a leap year or not.
* <p>
* February has 28 days in a standard year and 29 days in a leap year.
* April, June, September and November have 30 days.
* All other months have 31 days.
*
* @param leapYear true if the length is required for a leap year
* @return the length of this month in days, from 28 to 31
*/
public int length(boolean leapYear) {
switch (this) {
case FEBRUARY:
return (leapYear ? 29 : 28);
case APRIL:
case JUNE:
case SEPTEMBER:
case NOVEMBER:
return 30;
default:
return 31;
}
}
/**
* Gets the minimum length of this month in days.
* <p>
* February has a minimum length of 28 days.
* April, June, September and November have 30 days.
* All other months have 31 days.
*
* @return the minimum length of this month in days, from 28 to 31
*/
public int minLength() {
switch (this) {
case FEBRUARY:
return 28;
case APRIL:
case JUNE:
case SEPTEMBER:
case NOVEMBER:
return 30;
default:
return 31;
}
}
/**
* Gets the maximum length of this month in days.
* <p>
* February has a maximum length of 29 days.
* April, June, September and November have 30 days.
* All other months have 31 days.
*
* @return the maximum length of this month in days, from 29 to 31
*/
public int maxLength() {
switch (this) {
case FEBRUARY:
return 29;
case APRIL:
case JUNE:
case SEPTEMBER:
case NOVEMBER:
return 30;
default:
return 31;
}
}
//-----------------------------------------------------------------------
/**
* Gets the day-of-year corresponding to the first day of this month.
* <p>
* This returns the day-of-year that this month begins on, using the leap
* year flag to determine the length of February.
*
* @param leapYear true if the length is required for a leap year
* @return the day of year corresponding to the first day of this month, from 1 to 336
*/
public int firstDayOfYear(boolean leapYear) {
int leap = leapYear ? 1 : 0;
switch (this) {
case JANUARY:
return 1;
case FEBRUARY:
return 32;
case MARCH:
return 60 + leap;
case APRIL:
return 91 + leap;
case MAY:
return 121 + leap;
case JUNE:
return 152 + leap;
case JULY:
return 182 + leap;
case AUGUST:
return 213 + leap;
case SEPTEMBER:
return 244 + leap;
case OCTOBER:
return 274 + leap;
case NOVEMBER:
return 305 + leap;
case DECEMBER:
default:
return 335 + leap;
}
}
/**
* Gets the month corresponding to the first month of this quarter.
* <p>
* The year can be divided into four quarters.
* This method returns the first month of the quarter for the base month.
* January, February and March return January.
* April, May and June return April.
* July, August and September return July.
* October, November and December return October.
*
* @return the first month of the quarter corresponding to this month, not null
*/
public Month firstMonthOfQuarter() {
return ENUMS[(ordinal() / 3) * 3];
}
//-----------------------------------------------------------------------
/**
* Queries this month-of-year using the specified query.
* <p>
* This queries this month-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
/**代码未完, 请加载全部代码(NowJava.com).**/
关注时代Java
关注时代Java