Java tutorial
/* * Copyright 2001-2010 Stephen Colebourne * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.joda.time; import org.joda.convert.FromString; import org.joda.convert.ToString; import org.joda.time.base.BaseSingleFieldPeriod; import org.joda.time.field.FieldUtils; import org.joda.time.format.ISOPeriodFormat; import org.joda.time.format.PeriodFormatter; /** * An immutable time period representing a number of days. * <p> * <code>Days</code> is an immutable period that can only store days. * It does not store years, months or hours for example. As such it is a * type-safe way of representing a number of days in an application. * <p> * The number of days is set in the constructor, and may be queried using * <code>getDays()</code>. Basic mathematical operations are provided - * <code>plus()</code>, <code>minus()</code>, <code>multipliedBy()</code> and * <code>dividedBy()</code>. * <p> * <code>Days</code> is thread-safe and immutable. * * @author Stephen Colebourne * @since 1.4 */ public final class Days extends BaseSingleFieldPeriod { /** Constant representing zero days. */ public static final Days ZERO = new Days(0); /** Constant representing one day. */ public static final Days ONE = new Days(1); /** Constant representing two days. */ public static final Days TWO = new Days(2); /** Constant representing three days. */ public static final Days THREE = new Days(3); /** Constant representing four days. */ public static final Days FOUR = new Days(4); /** Constant representing five days. */ public static final Days FIVE = new Days(5); /** Constant representing six days. */ public static final Days SIX = new Days(6); /** Constant representing seven days. */ public static final Days SEVEN = new Days(7); /** Constant representing the maximum number of days that can be stored in this object. */ public static final Days MAX_VALUE = new Days(Integer.MAX_VALUE); /** Constant representing the minimum number of days that can be stored in this object. */ public static final Days MIN_VALUE = new Days(Integer.MIN_VALUE); /** The parser to use for this class. */ private static final PeriodFormatter PARSER = ISOPeriodFormat.standard().withParseType(PeriodType.days()); /** Serialization version. */ private static final long serialVersionUID = 87525275727380865L; //----------------------------------------------------------------------- /** * Obtains an instance of <code>Days</code> that may be cached. * <code>Days</code> is immutable, so instances can be cached and shared. * This factory method provides access to shared instances. * * @param days the number of days to obtain an instance for * @return the instance of Days */ public static Days days(int days) { switch (days) { case 0: return ZERO; case 1: return ONE; case 2: return TWO; case 3: return THREE; case 4: return FOUR; case 5: return FIVE; case 6: return SIX; case 7: return SEVEN; case Integer.MAX_VALUE: return MAX_VALUE; case Integer.MIN_VALUE: return MIN_VALUE; default: return new Days(days); } } //----------------------------------------------------------------------- /** * Creates a <code>Days</code> representing the number of whole days * between the two specified datetimes. This method correctly handles * any daylight savings time changes that may occur during the interval. * * @param start the start instant, must not be null * @param end the end instant, must not be null * @return the period in days * @throws IllegalArgumentException if the instants are null or invalid */ public static Days daysBetween(ReadableInstant start, ReadableInstant end) { int amount = BaseSingleFieldPeriod.between(start, end, DurationFieldType.days()); return Days.days(amount); } /** * Creates a <code>Days</code> representing the number of whole days * between the two specified partial datetimes. * <p> * The two partials must contain the same fields, for example you can specify * two <code>LocalDate</code> objects. * * @param start the start partial date, must not be null * @param end the end partial date, must not be null * @return the period in days * @throws IllegalArgumentException if the partials are null or invalid */ public static Days daysBetween(ReadablePartial start, ReadablePartial end) { if (start instanceof LocalDate && end instanceof LocalDate) { Chronology chrono = DateTimeUtils.getChronology(start.getChronology()); int days = chrono.days().getDifference(((LocalDate) end).getLocalMillis(), ((LocalDate) start).getLocalMillis()); return Days.days(days); } int amount = BaseSingleFieldPeriod.between(start, end, ZERO); return Days.days(amount); } /** * Creates a <code>Days</code> representing the number of whole days * in the specified interval. This method correctly handles any daylight * savings time changes that may occur during the interval. * * @param interval the interval to extract days from, null returns zero * @return the period in days * @throws IllegalArgumentException if the partials are null or invalid */ public static Days daysIn(ReadableInterval interval) { if (interval == null) { return Days.ZERO; } int amount = BaseSingleFieldPeriod.between(interval.getStart(), interval.getEnd(), DurationFieldType.days()); return Days.days(amount); } /** * Creates a new <code>Days</code> representing the number of complete * standard length days in the specified period. * <p> * This factory method converts all fields from the period to hours using standardised * durations for each field. Only those fields which have a precise duration in * the ISO UTC chronology can be converted. * <ul> * <li>One week consists of 7 days. * <li>One day consists of 24 hours. * <li>One hour consists of 60 minutes. * <li>One minute consists of 60 seconds. * <li>One second consists of 1000 milliseconds. * </ul> * Months and Years are imprecise and periods containing these values cannot be converted. * * @param period the period to get the number of hours from, null returns zero * @return the period in days * @throws IllegalArgumentException if the period contains imprecise duration values */ public static Days standardDaysIn(ReadablePeriod period) { int amount = BaseSingleFieldPeriod.standardPeriodIn(period, DateTimeConstants.MILLIS_PER_DAY); return Days.days(amount); } /** * Creates a new <code>Days</code> by parsing a string in the ISO8601 format 'PnD'. * <p> * The parse will accept the full ISO syntax of PnYnMnWnDTnHnMnS however only the * days component may be non-zero. If any other component is non-zero, an exception * will be thrown. * * @param periodStr the period string, null returns zero * @return the period in days * @throws IllegalArgumentException if the string format is invalid */ @FromString public static Days parseDays(String periodStr) { if (periodStr == null) { return Days.ZERO; } Period p = PARSER.parsePeriod(periodStr); return Days.days(p.getDays()); } //----------------------------------------------------------------------- /** * Creates a new instance representing a number of days. * You should consider using the factory method {@link #days(int)} * instead of the constructor. * * @param days the number of days to represent */ private Days(int days) { super(days); } /** * Resolves singletons. * * @return the singleton instance */ private Object readResolve() { return Days.days(getValue()); } //----------------------------------------------------------------------- /** * Gets the duration field type, which is <code>days</code>. * * @return the period type */ public DurationFieldType getFieldType() { return DurationFieldType.days(); } /** * Gets the period type, which is <code>days</code>. * * @return the period type */ public PeriodType getPeriodType() { return PeriodType.days(); } //----------------------------------------------------------------------- /** * Converts this period in days to a period in weeks assuming a * 7 day week. * <p> * This method allows you to convert between different types of period. * However to achieve this it makes the assumption that all weeks are * 7 days long. * This may not be true for some unusual chronologies. However, it is included * as it is a useful operation for many applications and business rules. * * @return a period representing the number of weeks for this number of days */ public Weeks toStandardWeeks() { return Weeks.weeks(getValue() / DateTimeConstants.DAYS_PER_WEEK); } /** * Converts this period in days to a period in hours assuming a * 24 hour day. * <p> * This method allows you to convert between different types of period. * However to achieve this it makes the assumption that all days are 24 hours long. * This is not true when daylight savings is considered and may also not * be true for some unusual chronologies. However, it is included * as it is a useful operation for many applications and business rules. * * @return a period representing the number of hours for this number of days * @throws ArithmeticException if the number of hours is too large to be represented */ public Hours toStandardHours() { return Hours.hours(FieldUtils.safeMultiply(getValue(), DateTimeConstants.HOURS_PER_DAY)); } /** * Converts this period in days to a period in minutes assuming a * 24 hour day and 60 minute hour. * <p> * This method allows you to convert between different types of period. * However to achieve this it makes the assumption that all days are 24 hours * long and all hours are 60 minutes long. * This is not true when daylight savings is considered and may also not * be true for some unusual chronologies. However, it is included * as it is a useful operation for many applications and business rules. * * @return a period representing the number of minutes for this number of days * @throws ArithmeticException if the number of minutes is too large to be represented */ public Minutes toStandardMinutes() { return Minutes.minutes(FieldUtils.safeMultiply(getValue(), DateTimeConstants.MINUTES_PER_DAY)); } /** * Converts this period in days to a period in seconds assuming a * 24 hour day, 60 minute hour and 60 second minute. * <p> * This method allows you to convert between different types of period. * However to achieve this it makes the assumption that all days are 24 hours * long, all hours are 60 minutes long and all minutes are 60 seconds long. * This is not true when daylight savings is considered and may also not * be true for some unusual chronologies. However, it is included * as it is a useful operation for many applications and business rules. * * @return a period representing the number of seconds for this number of days * @throws ArithmeticException if the number of seconds is too large to be represented */ public Seconds toStandardSeconds() { return Seconds.seconds(FieldUtils.safeMultiply(getValue(), DateTimeConstants.SECONDS_PER_DAY)); } //----------------------------------------------------------------------- /** * Converts this period in days to a duration in milliseconds assuming a * 24 hour day, 60 minute hour and 60 second minute. * <p> * This method allows you to convert from a period to a duration. * However to achieve this it makes the assumption that all days are 24 hours * long, all hours are 60 minutes and all minutes are 60 seconds. * This is not true when daylight savings time is considered, and may also * not be true for some unusual chronologies. However, it is included as it * is a useful operation for many applications and business rules. * * @return a duration equivalent to this number of days */ public Duration toStandardDuration() { long days = getValue(); // assign to a long return new Duration(days * DateTimeConstants.MILLIS_PER_DAY); } //----------------------------------------------------------------------- /** * Gets the number of days that this period represents. * * @return the number of days in the period */ public int getDays() { return getValue(); } //----------------------------------------------------------------------- /** * Returns a new instance with the specified number of days added. * <p> * This instance is immutable and unaffected by this method call. * * @param days the amount of days to add, may be negative * @return the new period plus the specified number of days * @throws ArithmeticException if the result overflows an int */ public Days plus(int days) { if (days == 0) { return this; } return Days.days(FieldUtils.safeAdd(getValue(), days)); } /** * Returns a new instance with the specified number of days added. * <p> * This instance is immutable and unaffected by this method call. * * @param days the amount of days to add, may be negative, null means zero * @return the new period plus the specified number of days * @throws ArithmeticException if the result overflows an int */ public Days plus(Days days) { if (days == null) { return this; } return plus(days.getValue()); } //----------------------------------------------------------------------- /** * Returns a new instance with the specified number of days taken away. * <p> * This instance is immutable and unaffected by this method call. * * @param days the amount of days to take away, may be negative * @return the new period minus the specified number of days * @throws ArithmeticException if the result overflows an int */ public Days minus(int days) { return plus(FieldUtils.safeNegate(days)); } /** * Returns a new instance with the specified number of days taken away. * <p> * This instance is immutable and unaffected by this method call. * * @param days the amount of days to take away, may be negative, null means zero * @return the new period minus the specified number of days * @throws ArithmeticException if the result overflows an int */ public Days minus(Days days) { if (days == null) { return this; } return minus(days.getValue()); } //----------------------------------------------------------------------- /** * Returns a new instance with the days multiplied by the specified scalar. * <p> * This instance is immutable and unaffected by this method call. * * @param scalar the amount to multiply by, may be negative * @return the new period multiplied by the specified scalar * @throws ArithmeticException if the result overflows an int */ public Days multipliedBy(int scalar) { return Days.days(FieldUtils.safeMultiply(getValue(), scalar)); } /** * Returns a new instance with the days divided by the specified divisor. * The calculation uses integer division, thus 3 divided by 2 is 1. * <p> * This instance is immutable and unaffected by this method call. * * @param divisor the amount to divide by, may be negative * @return the new period divided by the specified divisor * @throws ArithmeticException if the divisor is zero */ public Days dividedBy(int divisor) { if (divisor == 1) { return this; } return Days.days(getValue() / divisor); } //----------------------------------------------------------------------- /** * Returns a new instance with the days value negated. * * @return the new period with a negated value * @throws ArithmeticException if the result overflows an int */ public Days negated() { return Days.days(FieldUtils.safeNegate(getValue())); } //----------------------------------------------------------------------- /** * Is this days instance greater than the specified number of days. * * @param other the other period, null means zero * @return true if this days instance is greater than the specified one */ public boolean isGreaterThan(Days other) { if (other == null) { return getValue() > 0; } return getValue() > other.getValue(); } /** * Is this days instance less than the specified number of days. * * @param other the other period, null means zero * @return true if this days instance is less than the specified one */ public boolean isLessThan(Days other) { if (other == null) { return getValue() < 0; } return getValue() < other.getValue(); } //----------------------------------------------------------------------- /** * Gets this instance as a String in the ISO8601 duration format. * <p> * For example, "P4D" represents 4 days. * * @return the value as an ISO8601 string */ @ToString public String toString() { return "P" + String.valueOf(getValue()) + "D"; } }