/*
*******************************************************************************
* Copyright (C) 1996-2008, International Business Machines Corporation and *
* others. All Rights Reserved. *
*******************************************************************************
*/
package com.ibm.icu.util;
import java.io.Serializable;
import java.util.Date;
import java.util.Locale;
import com.ibm.icu.text.DateFormat;
/**
* <code>Calendar</code> is an abstract base class for converting between
* a <code>Date</code> object and a set of integer fields such as
* <code>YEAR</code>, <code>MONTH</code>, <code>DAY</code>, <code>HOUR</code>,
* and so on. (A <code>Date</code> object represents a specific instant in
* time with millisecond precision. See
* {@link Date}
* for information about the <code>Date</code> class.)
*
* <p><b>Note:</b> This class is similar, but not identical, to the class
* <code>java.util.Calendar</code>. Changes are detailed below.
*
* <p>
* Subclasses of <code>Calendar</code> interpret a <code>Date</code>
* according to the rules of a specific calendar system. ICU4J contains
* several subclasses implementing different international calendar systems.
*
* <p>
* Like other locale-sensitive classes, <code>Calendar</code> provides a
* class method, <code>getInstance</code>, for getting a generally useful
* object of this type. <code>Calendar</code>'s <code>getInstance</code> method
* returns a calendar of a type appropriate to the locale, whose
* time fields have been initialized with the current date and time:
* <blockquote>
* <pre>Calendar rightNow = Calendar.getInstance()</pre>
* </blockquote>
*
* <p>When a <code>ULocale</code> is used by <code>getInstance</code>, its
* '<code>calendar</code>' tag and value are retrieved if present. If a recognized
* value is supplied, a calendar is provided and configured as appropriate.
* Currently recognized tags are "buddhist", "chinese", "coptic", "ethiopic",
* "gregorian", "hebrew", "islamic", "islamic-civil", and "japanese". For
* example: <blockquote>
* <pre>Calendar cal = Calendar.getInstance(new ULocale("en_US@calendar=japanese"));</pre>
* </blockquote> will return an instance of JapaneseCalendar (using en_US conventions for
* minimum days in first week, start day of week, et cetera).
*
* <p>A <code>Calendar</code> object can produce all the time field values
* needed to implement the date-time formatting for a particular language and
* calendar style (for example, Japanese-Gregorian, Japanese-Traditional).
* <code>Calendar</code> defines the range of values returned by certain fields,
* as well as their meaning. For example, the first month of the year has value
* <code>MONTH</code> == <code>JANUARY</code> for all calendars. Other values
* are defined by the concrete subclass, such as <code>ERA</code> and
* <code>YEAR</code>. See individual field documentation and subclass
* documentation for details.
*
* <p>When a <code>Calendar</code> is <em>lenient</em>, it accepts a wider range
* of field values than it produces. For example, a lenient
* <code>GregorianCalendar</code> interprets <code>MONTH</code> ==
* <code>JANUARY</code>, <code>DAY_OF_MONTH</code> == 32 as February 1. A
* non-lenient <code>GregorianCalendar</code> throws an exception when given
* out-of-range field settings. When calendars recompute field values for
* return by <code>get()</code>, they normalize them. For example, a
* <code>GregorianCalendar</code> always produces <code>DAY_OF_MONTH</code>
* values between 1 and the length of the month.
*
* <p><code>Calendar</code> defines a locale-specific seven day week using two
* parameters: the first day of the week and the minimal days in first week
* (from 1 to 7). These numbers are taken from the locale resource data when a
* <code>Calendar</code> is constructed. They may also be specified explicitly
* through the API.
*
* <p>When setting or getting the <code>WEEK_OF_MONTH</code> or
* <code>WEEK_OF_YEAR</code> fields, <code>Calendar</code> must determine the
* first week of the month or year as a reference point. The first week of a
* month or year is defined as the earliest seven day period beginning on
* <code>getFirstDayOfWeek()</code> and containing at least
* <code>getMinimalDaysInFirstWeek()</code> days of that month or year. Weeks
* numbered ..., -1, 0 precede the first week; weeks numbered 2, 3,... follow
* it. Note that the normalized numbering returned by <code>get()</code> may be
* different. For example, a specific <code>Calendar</code> subclass may
* designate the week before week 1 of a year as week <em>n</em> of the previous
* year.
*
* <p> When computing a <code>Date</code> from time fields, two special
* circumstances may arise: there may be insufficient information to compute the
* <code>Date</code> (such as only year and month but no day in the month), or
* there may be inconsistent information (such as "Tuesday, July 15, 1996" --
* July 15, 1996 is actually a Monday).
*
* <p>
* <strong>Insufficient information.</strong> The calendar will use default
* information to specify the missing fields. This may vary by calendar; for
* the Gregorian calendar, the default for a field is the same as that of the
* start of the epoch: i.e., YEAR = 1970, MONTH = JANUARY, DATE = 1, etc.
*
* <p>
* <strong>Inconsistent information.</strong> If fields conflict, the calendar
* will give preference to fields set more recently. For example, when
* determining the day, the calendar will look for one of the following
* combinations of fields. The most recent combination, as determined by the
* most recently set single field, will be used.
*
* <blockquote>
* <pre>
* MONTH + DAY_OF_MONTH
* MONTH + WEEK_OF_MONTH + DAY_OF_WEEK
* MONTH + DAY_OF_WEEK_IN_MONTH + DAY_OF_WEEK
* DAY_OF_YEAR
* DAY_OF_WEEK + WEEK_OF_YEAR</pre>
* </blockquote>
*
* For the time of day:
*
* <blockquote>
* <pre>
* HOUR_OF_DAY
* AM_PM + HOUR</pre>
* </blockquote>
*
* <p>
* <strong>Note:</strong> for some non-Gregorian calendars, different
* fields may be necessary for complete disambiguation. For example, a full
* specification of the historial Arabic astronomical calendar requires year,
* month, day-of-month <em>and</em> day-of-week in some cases.
*
* <p>
* <strong>Note:</strong> There are certain possible ambiguities in
* interpretation of certain singular times, which are resolved in the
* following ways:
* <ol>
* <li> 24:00:00 "belongs" to the following day. That is,
* 23:59 on Dec 31, 1969 < 24:00 on Jan 1, 1970 < 24:01:00 on Jan 1, 1970
*
* <li> Although historically not precise, midnight also belongs to "am",
* and noon belongs to "pm", so on the same day,
* 12:00 am (midnight) < 12:01 am, and 12:00 pm (noon) < 12:01 pm
* </ol>
*
* <p>
* The date or time format strings are not part of the definition of a
* calendar, as those must be modifiable or overridable by the user at
* runtime. Use {@link DateFormat}
* to format dates.
*
* <p><strong>Field manipulation methods</strong></p>
*
* <p><code>Calendar</code> fields can be changed using three methods:
* <code>set()</code>, <code>add()</code>, and <code>roll()</code>.</p>
*
* <p><strong><code>set(f, value)</code></strong> changes field
* <code>f</code> to <code>value</code>. In addition, it sets an
* internal member variable to indicate that field <code>f</code> has
* been changed. Although field <code>f</code> is changed immediately,
* the calendar's milliseconds is not recomputed until the next call to
* <code>get()</code>, <code>getTime()</code>, or
* <code>getTimeInMillis()</code> is made. Thus, multiple calls to
* <code>set()</code> do not trigger multiple, unnecessary
* computations. As a result of changing a field using
* <code>set()</code>, other fields may also change, depending on the
* field, the field value, and the calendar system. In addition,
* <code>get(f)</code> will not necessarily return <code>value</code>
* after the fields have been recomputed. The specifics are determined by
* the concrete calendar class.</p>
*
* <p><em>Example</em>: Consider a <code>GregorianCalendar</code>
* originally set to August 31, 1999. Calling <code>set(Calendar.MONTH,
* Calendar.SEPTEMBER)</code> sets the calendar to September 31,
* 1999. This is a temporary internal representation that resolves to
* October 1, 1999 if <code>getTime()</code>is then called. However, a
* call to <code>set(Calendar.DAY_OF_MONTH, 30)</code> before the call to
* <code>getTime()</code> sets the calendar to September 30, 1999, since
* no recomputation occurs after <code>set()</code> itself.</p>
*
* <p><strong><code>add(f, delta)</code></strong> adds <code>delta</code>
* to field <code>f</code>. This is equivalent to calling <code>set(f,
* get(f) + delta)</code> with two adjustments:</p>
*
* <blockquote>
* <p><strong>Add rule 1</strong>. The value of field <code>f</code>
* after the call minus the value of field <code>f</code> before the
* call is <code>delta</code>, modulo any overflow that has occurred in
* field <code>f</code>. Overflow occurs when a field value exceeds its
* range and, as a result, the next larger field is incremented or
* decremented and the field value is adjusted back into its range.</p>
*
* <p><strong>Add rule 2</strong>. If a smaller field is expected to be
* invariant, but it is impossible for it to be equal to its
* prior value because of changes in its minimum or maximum after field
* <code>f</code> is changed, then its value is adjusted to be as close
* as possible to its expected value. A smaller field represents a
* smaller unit of time. <code>HOUR</code> is a smaller field than
* <code>DAY_OF_MONTH</code>. No adjustment is made to smaller fields
* that are not expected to be invariant. The calendar system
* determines what fields are expected to be invariant.</p>
* </blockquote>
*
* <p>In addition, unlike <code>set()</code>, <code>add()</code> forces
* an immediate recomputation of the calendar's milliseconds and all
* fields.</p>
*
* <p><em>Example</em>: Consider a <code>GregorianCalendar</code>
* originally set to August 31, 1999. Calling <code>add(Calendar.MONTH,
* 13)</code> sets the calendar to September 30, 2000. <strong>Add rule
* 1</strong> sets the <code>MONTH</code> field to September, since
* adding 13 months to August gives September of the next year. Since
* <code>DAY_OF_MONTH</code> cannot be 31 in September in a
* <code>GregorianCalendar</code>, <strong>add rule 2</strong> sets the
* <code>DAY_OF_MONTH</code> to 30, the closest possible value. Although
* it is a smaller field, <code>DAY_OF_WEEK</code> is not adjusted by
* rule 2, since it is expected to change when the month changes in a
* <code>GregorianCalendar</code>.</p>
*
* <p><strong><code>roll(f, delta)</code></strong> adds
* <code>delta</code> to field <code>f</code> without changing larger
* fields. This is equivalent to calling <code>add(f, delta)</code> with
* the following adjustment:</p>
*
* <blockquote>
* <p><strong>Roll rule</strong>. Larger fields are unchanged after the
* call. A larger field represents a larger unit of
* time. <code>DAY_OF_MONTH</code> is a larger field than
* <code>HOUR</code>.</p>
* </blockquote>
*
* <p><em>Example</em>: Consider a <code>GregorianCalendar</code>
* originally set to August 31, 1999. Calling <code>roll(Calendar.MONTH,
* 8)</code> sets the calendar to April 30, <strong>1999</strong>. Add
* rule 1 sets the <code>MONTH</code> field to April. Using a
* <code>GregorianCalendar</code>, the <code>DAY_OF_MONTH</code> cannot
* be 31 in the month April. Add rule 2 sets it to the closest possible
* value, 30. Finally, the <strong>roll rule</strong> maintains the
* <code>YEAR</code> field value of 1999.</p>
*
* <p><em>Example</em>: Consider a <code>GregorianCalendar</code>
* originally set to Sunday June 6, 1999. Calling
* <code>roll(Calendar.WEEK_OF_MONTH, -1)</code> sets the calendar to
* Tuesday June 1, 1999, whereas calling
* <code>add(Calendar.WEEK_OF_MONTH, -1)</code> sets the calendar to
* Sunday May 30, 1999. This is because the roll rule imposes an
* additional constraint: The <code>MONTH</code> must not change when the
* <code>WEEK_OF_MONTH</code> is rolled. Taken together with add rule 1,
* the resultant date must be between Tuesday June 1 and Saturday June
* 5. According to add rule 2, the <code>DAY_OF_WEEK</code>, an invariant
* when changing the <code>WEEK_OF_MONTH</code>, is set to Tuesday, the
* closest possible value to Sunday (where Sunday is the first day of the
* week).</p>
*
* <p><strong>Usage model</strong>. To motivate the behavior of
* <code>add()</code> and <code>roll()</code>, consider a user interface
* component with increment and decrement buttons for the month, day, and
* year, and an underlying <code>GregorianCalendar</code>. If the
* interface reads January 31, 1999 and the user presses the month
* increment button, what should it read? If the underlying
* implementation uses <code>set()</code>, it might read March 3, 1999. A
* better result would be February 28, 1999. Furthermore, if the user
* presses the month increment button again, it should read March 31,
* 1999, not March 28, 1999. By saving the original date and using either
* <code>add()</code> or <code>roll()</code>, depending on whether larger
* fields should be affected, the user interface can behave as most users
* will intuitively expect.</p>
*
* <p><b>Note:</b> You should always use {@link #roll roll} and {@link #add add} rather
* than attempting to perform arithmetic operations directly on the fields
* of a <tt>Calendar</tt>. It is quite possible for <tt>Calendar</tt> subclasses
* to have fields with non-linear behavior, for example missing months
* or days during non-leap years. The subclasses' <tt>add</tt> and <tt>roll</tt>
* methods will take this into account, while simple arithmetic manipulations
* may give invalid results.
*
* <p><big><big><b>Calendar Architecture in ICU4J</b></big></big></p>
*
* <p>Recently the implementation of <code>Calendar</code> has changed
* significantly in order to better support subclassing. The original
* <code>Calendar</code> class was designed to support subclassing, but
* it had only one implemented subclass, <code>GregorianCalendar</code>.
* With the implementation of several new calendar subclasses, including
* the <code>BuddhistCalendar</code>, <code>ChineseCalendar</code>,
* <code>HebrewCalendar</code>, <code>IslamicCalendar</code>, and
* <code>JapaneseCalendar</code>, the subclassing API has been reworked
* thoroughly. This section details the new subclassing API and other
* ways in which <code>com.ibm.icu.util.Calendar</code> differs from
* <code>java.util.Calendar</code>.
* </p>
*
* <p><big><b>Changes</b></big></p>
*
* <p>Overview of changes between the classic <code>Calendar</code>
* architecture and the new architecture.
*
* <ul>
*
* <li>The <code>fields[]</code> array is <code>private</code> now
* instead of <code>protected</code>. Subclasses must access it
* using the methods {@link #internalSet} and
* {@link #internalGet}. <b>Motivation:</b> Subclasses should
* not directly access data members.</li>
*
* <li>The <code>time</code> long word is <code>private</code> now
* instead of <code>protected</code>. Subclasses may access it using
* the method {@link #internalGetTimeInMillis}, which does not
* provoke an update. <b>Motivation:</b> Subclasses should not
* directly access data members.</li>
*
* <li>The scope of responsibility of subclasses has been drastically
* reduced. As much functionality as possible is implemented in the
* <code>Calendar</code> base class. As a result, it is much easier
* to subclass <code>Calendar</code>. <b>Motivation:</b> Subclasses
* should not have to reimplement common code. Certain behaviors are
* common across calendar systems: The definition and behavior of
* week-related fields and time fields, the arithmetic
* ({@link #add(int, int) add} and {@link #roll(int, int) roll}) behavior of many
* fields, and the field validation system.</li>
*
* <li>The subclassing API has been completely redesigned.</li>
*
* <li>The <code>Calendar</code> base class contains some Gregorian
* calendar algorithmic support that subclasses can use (specifically
* in {@link #handleComputeFields}). Subclasses can use the
* methods <code>getGregorianXxx()</code> to obtain precomputed
* values. <b>Motivation:</b> This is required by all
* <code>Calendar</code> subclasses in order to implement consistent
* time zone behavior, and Gregorian-derived systems can use the
* already computed data.</li>
*
* <li>The <code>FIELD_COUNT</code> constant has been removed. Use
* {@link #getFieldCount}. In addition, framework API has been
* added to allow subclasses to define additional fields.
* <b>Motivation: </b>The number of fields is not constant across
* calendar systems.</li>
*
* <li>The range of handled dates has been narrowed from +/-
* ~300,000,000 years to +/- ~5,000,000 years. In practical terms
* this should not affect clients. However, it does mean that client
* code cannot be guaranteed well-behaved results with dates such as
* <code>Date(Long.MIN_VALUE)</code> or
* <code>Date(Long.MAX_VALUE)</code>. Instead, the
* <code>Calendar</code> constants {@link #MIN_DATE},
* {@link #MAX_DATE}, {@link #MIN_MILLIS},
* {@link #MAX_MILLIS}, {@link #MIN_JULIAN}, and
* {@link #MAX_JULIAN} should be used. <b>Motivation:</b> With
* the addition of the {@link #JULIAN_DAY} field, Julian day
* numbers must be restricted to a 32-bit <code>int</code>. This
* restricts the overall supported range. Furthermore, restricting
* the supported range simplifies the computations by removing
* special case code that was used to accomodate arithmetic overflow
* at millis near <code>Long.MIN_VALUE</code> and
* <code>Long.MAX_VALUE</code>.</li>
*
* <li>New fields are implemented: {@link #JULIAN_DAY} defines
* single-field specification of the
* date. {@link #MILLISECONDS_IN_DAY} defines a single-field
* specification of the wall time. {@link #DOW_LOCAL} and
* {@link #YEAR_WOY} implement localized day-of-week and
* week-of-year behavior.</li>
*
* <li>Subclasses can access millisecond constants
* {@link #ONE_SECOND}, {@link #ONE_MINUTE},
* {@link #ONE_HOUR}, {@link #ONE_DAY}, and
* {@link #ONE_WEEK} defined in <code>Calendar</code>.</li>
*
* <li>New API has been added to suport calendar-specific subclasses
* of <code>DateFormat</code>.</li>
*
* <li>Several subclasses have been implemented, representing
* various international calendar systems.</li>
*
* </ul>
*
* <p><big><b>Subclass API</b></big></p>
*
* <p>The original <code>Calendar</code> API was based on the experience
* of implementing a only a single subclass,
* <code>GregorianCalendar</code>. As a result, all of the subclassing
* kinks had not been worked out. The new subclassing API has been
* refined based on several implemented subclasses. This includes methods
* that must be overridden and methods for subclasses to call. Subclasses
* no longer have direct access to <code>fields</code> and
* <code>stamp</code>. Instead, they have new API to access
* these. Subclasses are able to allocate the <code>fields</code> array
* through a protected framework method; this allows subclasses to
* specify additional fields. </p>
*
* <p>More functionality has been moved into the base class. The base
* class now contains much of the computational machinery to support the
* Gregorian calendar. This is based on two things: (1) Many calendars
* are based on the Gregorian calendar (such as the Buddhist and Japanese
* imperial calendars). (2) <em>All</em> calendars require basic
* Gregorian support in order to handle timezone computations. </p>
*
* <p>Common computations have been moved into
* <code>Calendar</code>. Subclasses no longer compute the week related
* fields and the time related fields. These are commonly handled for all
* calendars by the base class. </p>
*
* <p><b>Subclass computation of time <tt>=></tt> fields</b>
*
* <p>The {@link #ERA}, {@link #YEAR},
* {@link #EXTENDED_YEAR}, {@link #MONTH},
* {@link #DAY_OF_MONTH}, and {@link #DAY_OF_YEAR} fields are
* computed by the subclass, based on the Julian day. All other fields
* are computed by <code>Calendar</code>.
*
* <ul>
*
* <li>Subclasses should implement {@link #handleComputeFields}
* to compute the {@link #ERA}, {@link #YEAR},
* {@link #EXTENDED_YEAR}, {@link #MONTH},
* {@link #DAY_OF_MONTH}, and {@link #DAY_OF_YEAR} fields,
* based on the value of the {@link #JULIAN_DAY} field. If there
* are calendar-specific fields not defined by <code>Calendar</code>,
* they must also be computed. These are the only fields that the
* subclass should compute. All other fields are computed by the base
* class, so time and week fields behave in a consistent way across
* all calendars. The default version of this method in
* <code>Calendar</code> implements a proleptic Gregorian
* calendar. Within this method, subclasses may call
* <code>getGregorianXxx()</code> to obtain the Gregorian calendar
* month, day of month, and extended year for the given date.</li>
*
* </ul>
*
* <p><b>Subclass computation of fields <tt>=></tt> time</b>
*
* <p>The interpretation of most field values is handled entirely by
* <code>Calendar</code>. <code>Calendar</code> determines which fields
* are set, which are not, which are set more recently, and so on. In
* addition, <code>Calendar</code> handles the computation of the time
* from the time fields and handles the week-related fields. The only
* thing the subclass must do is determine the extended year, based on
* the year fields, and then, given an extended year and a month, it must
* return a Julian day number.
*
* <ul>
*
* <li>Subclasses should implement {@link #handleGetExtendedYear}
* to return the extended year for this calendar system, based on the
* {@link #YEAR}, {@link #EXTENDED_YEAR}, and any fields that
* the calendar system uses that are larger than a year, such as
* {@link #ERA}.</li>
*
* <li>Subclasses should implement {@link #handleComputeMonthStart}
* to return the Julian day number
* associated with a month and extended year. This is the Julian day
* number of the day before the first day of the month. The month
* number is zero-based. This computation should not depend on any
* field values.</li>
*
* </ul>
*
* <p><b>Other methods</b>
*
* <ul>
*
* <li>Subclasses should implement {@link #handleGetMonthLength}
* to return the number of days in a
* given month of a given extended year. The month number, as always,
* is zero-based.</li>
*
* <li>Subclasses should implement {@link #handleGetYearLength}
* to return the number of days in the given
* extended year. This method is used by
* <tt>computeWeekFields</tt> to compute the
* {@link #WEEK_OF_YEAR} and {@link #YEAR_WOY} fields.</li>
*
* <li>Subclasses should implement {@link #handleGetLimit}
* to return the {@link #MINIMUM},
* {@link #GREATEST_MINIMUM}, {@link #LEAST_MAXIMUM}, or
* {@link #MAXIMUM} of a field, depending on the value of
* <code>limitType</code>. This method only needs to handle the
* fields {@link #ERA}, {@link #YEAR}, {@link #MONTH},
* {@link #WEEK_OF_YEAR}, {@link #WEEK_OF_MONTH},
* {@link #DAY_OF_MONTH}, {@link #DAY_OF_YEAR},
* {@link #DAY_OF_WEEK_IN_MONTH}, {@link #YEAR_WOY}, and
* {@link #EXTENDED_YEAR}. Other fields are invariant (with
* respect to calendar system) and are handled by the base
* class.</li>
*
* <li>Optionally, subclasses may override {@link #validateField}
* to check any subclass-specific fields. If the
* field's value is out of range, the method should throw an
* <code>IllegalArgumentException</code>. The method may call
* <code>super.validateField(field)</code> to handle fields in a
* generic way, that is, to compare them to the range
* <code>getMinimum(field)</code>..<code>getMaximum(field)</code>.</li>
*
* <li>Optionally, subclasses may override
* {@link #handleCreateFields} to create an <code>int[]</code>
* array large enough to hold the calendar's fields. This is only
* necessary if the calendar defines additional fields beyond those
* defined by <code>Calendar</code>. The length of the result must be
* at least {@link #BASE_FIELD_COUNT} and no more than
* {@link #MAX_FIELD_COUNT}.</li>
*
* <li>Optionally, subclasses may override
* {@link #handleGetDateFormat} to create a
* <code>DateFormat</code> appropriate to this calendar. This is only
* required if a calendar subclass redefines the use of a field (for
* example, changes the {@link #ERA} field from a symbolic field
* to a numeric one) or defines an additional field.</li>
*
* <li>Optionally, subclasses may override {@link #roll roll} and
* {@link #add add} to handle fields that are discontinuous. For
* example, in the Hebrew calendar the month "Adar I" only
* occurs in leap years; in other years the calendar jumps from
* Shevat (month #4) to Adar (month #6). The {@link
* HebrewCalendar#add HebrewCalendar.add} and {@link
* HebrewCalendar#roll HebrewCalendar.roll} methods take this into
* account, so that adding 1 month to Shevat gives the proper result
* (Adar) in a non-leap year. The protected utility method {@link
* #pinField pinField} is often useful when implementing these two
* methods. </li>
*
* </ul>
*
* <p><big><b>Normalized behavior</b></big>
*
* <p>The behavior of certain fields has been made consistent across all
* calendar systems and implemented in <code>Calendar</code>.
*
* <ul>
*
* <li>Time is normalized. Even though some calendar systems transition
* between days at sunset or at other times, all ICU4J calendars
* transition between days at <em>local zone midnight</em>. This
* allows ICU4J to centralize the time computations in
* <code>Calendar</code> and to maintain basic correpsondences
* between calendar systems. Affected fields: {@link #AM_PM},
* {@link #HOUR}, {@link #HOUR_OF_DAY}, {@link #MINUTE},
* {@link #SECOND}, {@link #MILLISECOND},
* {@link #ZONE_OFFSET}, and {@link #DST_OFFSET}.</li>
*
* <li>DST behavior is normalized. Daylight savings time behavior is
* computed the same for all calendar systems, and depends on the
* value of several <code>GregorianCalendar</code> fields: the
* {@link #YEAR}, {@link #MONTH}, and
* {@link #DAY_OF_MONTH}. As a result, <code>Calendar</code>
* always computes these fields, even for non-Gregorian calendar
* systems. These fields are available to subclasses.</li>
*
* <li>Weeks are normalized. Although locales define the week
* differently, in terms of the day on which it starts, and the
* designation of week number one of a month or year, they all use a
* common mechanism. Furthermore, the day of the week has a simple
* and consistent definition throughout history. For example,
* although the Gregorian calendar introduced a discontinuity when
* first instituted, the day of week was not disrupted. For this
* reason, the fields {@link #DAY_OF_WEEK}, <code>WEEK_OF_YEAR,
* WEEK_OF_MONTH</code>, {@link #DAY_OF_WEEK_IN_MONTH},
* {@link #DOW_LOCAL}, {@link #YEAR_WOY} are all computed in
* a consistent way in the base class, based on the
* {@link #EXTENDED_YEAR}, {@link #DAY_OF_YEAR},
* {@link #MONTH}, and {@link #DAY_OF_MONTH}, which are
* computed by the subclass.</li>
*
* </ul>
*
* <p><big><b>Supported range</b></big>
*
* <p>The allowable range of <code>Calendar</code> has been
* narrowed. <code>GregorianCalendar</code> used to attempt to support
* the range of dates with millisecond values from
* <code>Long.MIN_VALUE</code> to <code>Long.MAX_VALUE</code>. This
* introduced awkward constructions (hacks) which slowed down
* performance. It also introduced non-uniform behavior at the
* boundaries. The new <code>Calendar</code> protocol specifies the
* maximum range of supportable dates as those having Julian day numbers
* of <code>-0x7F000000</code> to <code>+0x7F000000</code>. This
* corresponds to years from ~5,000,000 BCE to ~5,000,000 CE. Programmers
* should use the constants {@link #MIN_DATE} (or
* {@link #MIN_MILLIS} or {@link #MIN_JULIAN}) and
* {@link #MAX_DATE} (or {@link #MAX_MILLIS} or
* {@link #MAX_JULIAN}) in <code>Calendar</code> to specify an
* extremely early or extremely late date.</p>
*
* <p><big><b>General notes</b></big>
*
* <ul>
*
* <li>Calendars implementations are <em>proleptic</em>. For example,
* even though the Gregorian calendar was not instituted until the
* 16th century, the <code>GregorianCalendar</code> class supports
* dates before the historical onset of the calendar by extending the
* calendar system backward in time. Similarly, the
* <code>HebrewCalendar</code> extends backward before the start of
* its epoch into zero and negative years. Subclasses do not throw
* exceptions because a date precedes the historical start of a
* calendar system. Instead, they implement
* {@link #handleGetLimit} to return appropriate limits on
* {@link #YEAR}, {@link #ERA}, etc. fields. Then, if the
* calendar is set to not be lenient, out-of-range field values will
* trigger an exception.</li>
*
* <li>Calendar system subclasses compute a <em>extended
* year</em>. This differs from the {@link #YEAR} field in that
* it ranges over all integer values, including zero and negative
* values, and it encapsulates the information of the
* {@link #YEAR} field and all larger fields. Thus, for the
* Gregorian calendar, the {@link #EXTENDED_YEAR} is computed as
* <code>ERA==AD ? YEAR : 1-YEAR</code>. Another example is the Mayan
* long count, which has years (<code>KUN</code>) and nested cycles
* of years (<code>KATUN</code> and <code>BAKTUN</code>). The Mayan
* {@link #EXTENDED_YEAR} is computed as <code>TUN + 20 * (KATUN
* + 20 * BAKTUN)</code>. The <code>Calendar</code> base class uses
* the {@link #EXTENDED_YEAR} field to compute the week-related
* fields.</li>
*
* </ul>
*
* @see Date
* @see GregorianCalendar
* @see TimeZone
* @see DateFormat
* @author Mark Davis, David Goldsmith, Chen-Lieh Huang, Alan Liu, Laura Werner
* @stable ICU 2.0
*/
public class Calendar implements Serializable, Cloneable, Comparable {
private static final long serialVersionUID = 1;
/**
* @internal
*/
public final java.util.Calendar calendar;
/**
* @internal
* @param delegate the Calendar to which to delegate
*/
public Calendar(java.util.Calendar delegate) {
this.calendar = delegate;
}
/**
* Field number for <code>get</code> and <code>set</code> indicating the
* era, e.g., AD or BC in the Julian calendar. This is a calendar-specific
* value; see subclass documentation.
* @see GregorianCalendar#AD
* @see GregorianCalendar#BC
* @stable ICU 2.0
*/
public final static int ERA = 0;
/**
* Field number for <code>get</code> and <code>set</code> indicating the
* year. This is a calendar-specific value; see subclass documentation.
* @stable ICU 2.0
*/
public final static int YEAR = 1;
/**
* Field number for <code>get</code> and <code>set</code> indicating the
* month. This is a calendar-specific value. The first month of the year is
* <code>JANUARY</code>; the last depends on the number of months in a year.
* @see #JANUARY
* @see #FEBRUARY
* @see #MARCH
* @see #APRIL
* @see #MAY
* @see #JUNE
* @see #JULY
* @see #AUGUST
* @see #SEPTEMBER
* @see #OCTOBER
* @see #NOVEMBER
* @see #DECEMBER
* @see #UNDECIMBER
* @stable ICU 2.0
*/
public final static int MONTH = 2;
/**
* Field number for <code>get</code> and <code>set</code> indicating the
* week number within the current year. The first week of the year, as
* defined by <code>getFirstDayOfWeek()</code> and
* <code>getMinimalDaysInFirstWeek()</code>, has value 1. Subclasses define
* the value of <code>WEEK_OF_YEAR</code> for days before the first week of
* the year.
* @see #getFirstDayOfWeek
* @see #getMinimalDaysInFirstWeek
* @stable ICU 2.0
*/
public final static int WEEK_OF_YEAR = 3;
/**
* Field number for <code>get</code> and <code>set</code> indicating the
* week number within the current month. The first week of the month, as
* defined by <code>getFirstDayOfWeek()</code> and
* <code>getMinimalDaysInFirstWeek()</code>, has value 1. Subclasses define
* the value of <code>WEEK_OF_MONTH</code> for days before the first week of
* the month.
* @see #getFirstDayOfWeek
* @see #getMinimalDaysInFirstWeek
* @stable ICU 2.0
*/
public final static int WEEK_OF_MONTH = 4;
/**
* Field number for <code>get</code> and <code>set</code> indicating the
* day of the month. This is a synonym for <code>DAY_OF_MONTH</code>.
* The first day of the month has value 1.
* @see #DAY_OF_MONTH
* @stable ICU 2.0
*/
public final static int DATE = 5;
/**
* Field number for <code>get</code> and <code>set</code> indicating the
* day of the month. This is a synonym for <code>DATE</code>.
* The first day of the month has value 1.
* @see #DATE
* @stable ICU 2.0
*/
public final static int DAY_OF_MONTH = 5;
/**
* Field number for <code>get</code> and <code>set</code> indicating the day
* number within the current year. The first day of the year has value 1.
* @stable ICU 2.0
*/
public final static int DAY_OF_YEAR = 6;
/**
* Field number for <code>get</code> and <code>set</code> indicating the day
* of the week. This field takes values <code>SUNDAY</code>,
* <code>MONDAY</code>, <code>TUESDAY</code>, <code>WEDNESDAY</code>,
* <code>THURSDAY</code>, <code>FRIDAY</code>, and <code>SATURDAY</code>.
* @see #SUNDAY
* @see #MONDAY
* @see #TUESDAY
* @see #WEDNESDAY
* @see #THURSDAY
* @see #FRIDAY
* @see #SATURDAY
* @stable ICU 2.0
*/
public final static int DAY_OF_WEEK = 7;
/**
* Field number for <code>get</code> and <code>set</code> indicating the
* ordinal number of the day of the week within the current month. Together
* with the <code>DAY_OF_WEEK</code> field, this uniquely specifies a day
* within a month. Unlike <code>WEEK_OF_MONTH</code> and
* <code>WEEK_OF_YEAR</code>, this field's value does <em>not</em> depend on
* <code>getFirstDayOfWeek()</code> or
* <code>getMinimalDaysInFirstWeek()</code>. <code>DAY_OF_MONTH 1</code>
* through <code>7</code> always correspond to <code>DAY_OF_WEEK_IN_MONTH
* 1</code>; <code>8</code> through <code>15</code> correspond to
* <code>DAY_OF_WEEK_IN_MONTH 2</code>, and so on.
* <code>DAY_OF_WEEK_IN_MONTH 0</code> indicates the week before
* <code>DAY_OF_WEEK_IN_MONTH 1</code>. Negative values count back from the
* end of the month, so the last Sunday of a month is specified as
* <code>DAY_OF_WEEK = SUNDAY, DAY_OF_WEEK_IN_MONTH = -1</code>. Because
* negative values count backward they will usually be aligned differently
* within the month than positive values. For example, if a month has 31
* days, <code>DAY_OF_WEEK_IN_MONTH -1</code> will overlap
* <code>DAY_OF_WEEK_IN_MONTH 5</code> and the end of <code>4</code>.
* @see #DAY_OF_WEEK
* @see #WEEK_OF_MONTH
* @stable ICU 2.0
*/
public final static int DAY_OF_WEEK_IN_MONTH = 8;
/**
* Field number for <code>get</code> and <code>set</code> indicating
* whether the <code>HOUR</code> is before or after noon.
* E.g., at 10:04:15.250 PM the <code>AM_PM</code> is <code>PM</code>.
* @see #AM
* @see #PM
* @see #HOUR
* @stable ICU 2.0
*/
public final static int AM_PM = 9;
/**
* Field number for <code>get</code> and <code>set</code> indicating the
* hour of the morning or afternoon. <code>HOUR</code> is used for the 12-hour
* clock.
* E.g., at 10:04:15.250 PM the <code>HOUR</code> is 10.
* @see #AM_PM
* @see #HOUR_OF_DAY
* @stable ICU 2.0
*/
public final static int HOUR = 10;
/**
* Field number for <code>get</code> and <code>set</code> indicating the
* hour of the day. <code>HOUR_OF_DAY</code> is used for the 24-hour clock.
* E.g., at 10:04:15.250 PM the <code>HOUR_OF_DAY</code> is 22.
* @see #HOUR
* @stable ICU 2.0
*/
public final static int HOUR_OF_DAY = 11;
/**
* Field number for <code>get</code> and <code>set</code> indicating the
* minute within the hour.
* E.g., at 10:04:15.250 PM the <code>MINUTE</code> is 4.
* @stable ICU 2.0
*/
public final static int MINUTE = 12;
/**
* Field number for <code>get</code> and <code>set</code> indicating the
* second within the minute.
* E.g., at 10:04:15.250 PM the <code>SECOND</code> is 15.
* @stable ICU 2.0
*/
public final static int SECOND = 13;
/**
* Field number for <code>get</code> and <code>set</code> indicating the
* millisecond within the second.
* E.g., at 10:04:15.250 PM the <code>MILLISECOND</code> is 250.
* @stable ICU 2.0
*/
public final static int MILLISECOND = 14;
/**
* Field number for <code>get</code> and <code>set</code> indicating the
* raw offset from GMT in milliseconds.
* @stable ICU 2.0
*/
public final static int ZONE_OFFSET = 15;
/**
* Field number for <code>get</code> and <code>set</code> indicating the
* daylight savings offset in milliseconds.
* @stable ICU 2.0
*/
public final static int DST_OFFSET = 16;
/**
* Field number for <code>get()</code> and <code>set()</code>
* indicating the extended year corresponding to the
* <code>WEEK_OF_YEAR</code> field. This may be one greater or less
* than the value of <code>EXTENDED_YEAR</code>.
* @stable ICU 2.0
*/
public static final int YEAR_WOY = 17;
/**
* Field number for <code>get()</code> and <code>set()</code>
* indicating the localized day of week. This will be a value from 1
* to 7 inclusive, with 1 being the localized first day of the week.
* @stable ICU 2.0
*/
public static final int DOW_LOCAL = 18;
/**
* Field number for <code>get()</code> and <code>set()</code>
* indicating the extended year. This is a single number designating
* the year of this calendar system, encompassing all supra-year
* fields. For example, for the Julian calendar system, year numbers
* are positive, with an era of BCE or CE. An extended year value for
* the Julian calendar system assigns positive values to CE years and
* negative values to BCE years, with 1 BCE being year 0.
* @stable ICU 2.0
*/
public static final int EXTENDED_YEAR = 19;
/**
* Field number for <code>get()</code> and <code>set()</code>
* indicating the modified Julian day number. This is different from
* the conventional Julian day number in two regards. First, it
* demarcates days at local zone midnight, rather than noon GMT.
* Second, it is a local number; that is, it depends on the local time
* zone. It can be thought of as a single number that encompasses all
* the date-related fields.
* @stable ICU 2.0
*/
public static final int JULIAN_DAY = 20;
/**
* Field number for <code>get()</code> and <code>set()</code>
* indicating the milliseconds in the day. This ranges from 0 to
* 23:59:59.999 (regardless of DST). This field behaves
* <em>exactly</em> like a composite of all time-related fields, not
* including the zone fields. As such, it also reflects
* discontinuities of those fields on DST transition days. On a day of
* DST onset, it will jump forward. On a day of DST cessation, it will
* jump backward. This reflects the fact that is must be combined with
* the DST_OFFSET field to obtain a unique local time value.
* @stable ICU 2.0
*/
public static final int MILLISECONDS_IN_DAY = 21;
/**
* The number of fields defined by this class. Subclasses may define
* addition fields starting with this number.
* @stable ICU 2.0
*/
protected static final int BASE_FIELD_COUNT = 22;
/**
* The maximum number of fields possible. Subclasses must not define
* more total fields than this number.
* @stable ICU 2.0
*/
protected static final int MAX_FIELD_COUNT = 32;
/**
* Value of the <code>DAY_OF_WEEK</code> field indicating
* Sunday.
* @stable ICU 2.0
*/
public final static int SUNDAY = 1;
/**
* Value of the <code>DAY_OF_WEEK</code> field indicating
* Monday.
* @stable ICU 2.0
*/
public final static int MONDAY = 2;
/**
* Value of the <code>DAY_OF_WEEK</code> field indicating
* Tuesday.
* @stable ICU 2.0
*/
public final static int TUESDAY = 3;
/**
* Value of the <code>DAY_OF_WEEK</code> field indicating
* Wednesday.
* @stable ICU 2.0
*/
public final static int WEDNESDAY = 4;
/**
* Value of the <code>DAY_OF_WEEK</code> field indicating
* Thursday.
* @stable ICU 2.0
*/
public final static int THURSDAY = 5;
/**
* Value of the <code>DAY_OF_WEEK</code> field indicating
* Friday.
* @stable ICU 2.0
*/
public final static int FRIDAY = 6;
/**
* Value of the <code>DAY_OF_WEEK</code> field indicating
* Saturday.
* @stable ICU 2.0
*/
public final static int SATURDAY = 7;
/**
* Value of the <code>MONTH</code> field indicating the
* first month of the year.
* @stable ICU 2.0
*/
public final static int JANUARY = 0;
/**
* Value of the <code>MONTH</code> field indicating the
* second month of the year.
* @stable ICU 2.0
*/
public final static int FEBRUARY = 1;
/**
* Value of the <code>MONTH</code> field indicating the
* third month of the year.
* @stable ICU 2.0
*/
public final static int MARCH = 2;
/**
* Value of the <code>MONTH</code> field indicating the
* fourth month of the year.
* @stable ICU 2.0
*/
public final static int APRIL = 3;
/**
* Value of the <code>MONTH</code> field indicating the
* fifth month of the year.
* @stable ICU 2.0
*/
public final static int MAY = 4;
/**
* Value of the <code>MONTH</code> field indicating the
* sixth month of the year.
* @stable ICU 2.0
*/
public final static int JUNE = 5;
/**
* Value of the <code>MONTH</code> field indicating the
* seventh month of the year.
* @stable ICU 2.0
*/
public final static int JULY = 6;
/**
* Value of the <code>MONTH</code> field indicating the
* eighth month of the year.
* @stable ICU 2.0
*/
public final static int AUGUST = 7;
/**
* Value of the <code>MONTH</code> field indicating the
* ninth month of the year.
* @stable ICU 2.0
*/
public final static int SEPTEMBER = 8;
/**
* Value of the <code>MONTH</code> field indicating the
* tenth month of the year.
* @stable ICU 2.0
*/
public final static int OCTOBER = 9;
/**
* Value of the <code>MONTH</code> field indicating the
* eleventh month of the year.
* @stable ICU 2.0
*/
public final static int NOVEMBER = 10;
/**
* Value of the <code>MONTH</code> field indicating the
* twelfth month of the year.
* @stable ICU 2.0
*/
public final static int DECEMBER = 11;
/**
* Value of the <code>MONTH</code> field indicating the
* thirteenth month of the year. Although <code>GregorianCalendar</code>
* does not use this value, lunar calendars do.
* @stable ICU 2.0
*/
public final static int UNDECIMBER = 12;
/**
* Value of the <code>AM_PM</code> field indicating the
* period of the day from midnight to just before noon.
* @stable ICU 2.0
*/
public final static int AM = 0;
/**
* Value of the <code>AM_PM</code> field indicating the
* period of the day from noon to just before midnight.
* @stable ICU 2.0
*/
public final static int PM = 1;
/**
* Value returned by getDayOfWeekType(int dayOfWeek) to indicate a
* weekday.
* @see #WEEKEND
* @see #WEEKEND_ONSET
* @see #WEEKEND_CEASE
* @see #getDayOfWeekType
* @stable ICU 2.0
*/
public static final int WEEKDAY = 0;
/**
* Value returned by getDayOfWeekType(int dayOfWeek) to indicate a
* weekend day.
* @see #WEEKDAY
* @see #WEEKEND_ONSET
* @see #WEEKEND_CEASE
* @see #getDayOfWeekType
* @stable ICU 2.0
*/
public static final int WEEKEND = 1;
/**
* Value returned by getDayOfWeekType(int dayOfWeek) to indicate a
* day that starts as a weekday and transitions to the weekend.
* Call getWeekendTransition() to get the point of transition.
* @see #WEEKDAY
* @see #WEEKEND
* @see #WEEKEND_CEASE
* @see #getDayOfWeekType
* @stable ICU 2.0
*/
public static final int WEEKEND_ONSET = 2;
/**
* Value returned by getDayOfWeekType(int dayOfWeek) to indicate a
* day that starts as the weekend and transitions to a weekday.
* Call getWeekendTransition() to get the point of transition.
* @see #WEEKDAY
* @see #WEEKEND
* @see #WEEKEND_ONSET
* @see #getDayOfWeekType
* @stable ICU 2.0
*/
public static final int WEEKEND_CEASE = 3;
/**
* Gets a calendar using the default time zone and locale.
* @return a Calendar.
* @stable ICU 2.0
*/
public static synchronized Calendar getInstance() {
return new Calendar(java.util.Calendar.getInstance());
}
/**
* Gets a calendar using the specified time zone and default locale.
* @param zone the time zone to use
* @return a Calendar.
* @stable ICU 2.0
*/
public static synchronized Calendar getInstance(TimeZone zone) {
return new Calendar(java.util.Calendar.getInstance(zone.timeZone));
}
/**
* Gets a calendar using the default time zone and specified locale.
* @param aLocale the locale for the week data
* @return a Calendar.
* @stable ICU 2.0
*/
public static synchronized Calendar getInstance(Locale aLocale) {
return new Calendar(java.util.Calendar.getInstance(aLocale));
}
/**
* Gets a calendar using the default time zone and specified locale.
* @param locale the ulocale for the week data
* @return a Calendar.
* @stable ICU 3.2
*/
public static synchronized Calendar getInstance(ULocale locale) {
return new Calendar(java.util.Calendar.getInstance(locale.toLocale()));
}
/**
* Gets a calendar with the specified time zone and locale.
* @param zone the time zone to use
* @param aLocale the locale for the week data
* @return a Calendar.
* @stable ICU 2.0
*/
public static synchronized Calendar getInstance(TimeZone zone, Locale aLocale) {
return new Calendar(java.util.Calendar.getInstance(zone.timeZone, aLocale));
}
/**
* Gets a calendar with the specified time zone and locale.
* @param zone the time zone to use
* @param locale the ulocale for the week data
* @return a Calendar.
* @stable ICU 3.2
*/
public static synchronized Calendar getInstance(TimeZone zone, ULocale locale) {
return new Calendar(java.util.Calendar.getInstance(zone.timeZone, locale.toLocale()));
}
/**
* Gets the list of locales for which Calendars are installed.
* @return the list of locales for which Calendars are installed.
* @stable ICU 2.0
*/
public static Locale[] getAvailableLocales() {
return java.util.Calendar.getAvailableLocales();
}
/**
* Gets the list of locales for which Calendars are installed.
* @return the list of locales for which Calendars are installed.
* @draft ICU 3.2 (retain)
*/
public static ULocale[] getAvailableULocales() {
if (availableULocales == null) {
Locale[] locales = java.util.Calendar.getAvailableLocales();
ULocale[] ulocales = new ULocale[locales.length];
for (int i = 0; i < locales.length; ++i) {
ulocales[i] = ULocale.forLocale(locales[i]);
}
availableULocales = ulocales;
}
return (ULocale[])availableULocales.clone();
}
private static ULocale[] availableULocales;
/**
* Gets this Calendar's current time.
* @return the current time.
* @stable ICU 2.0
*/
public final Date getTime() {
return calendar.getTime();
}
/**
* Sets this Calendar's current time with the given Date.
* <p>
* Note: Calling <code>setTime()</code> with
* <code>Date(Long.MAX_VALUE)</code> or <code>Date(Long.MIN_VALUE)</code>
* may yield incorrect field values from <code>get()</code>.
* @param date the given Date.
* @stable ICU 2.0
*/
public final void setTime(Date date) {
calendar.setTime(date);
}
/**
* Gets this Calendar's current time as a long.
* @return the current time as UTC milliseconds from the epoch.
* @stable ICU 2.0
*/
public long getTimeInMillis() {
return calendar.getTime().getTime();
}
/**
* Sets this Calendar's current time from the given long value.
* @param millis the new time in UTC milliseconds from the epoch.
* @stable ICU 2.0
*/
public void setTimeInMillis(long millis) {
calendar.setTime(new Date(millis));
}
/**
* Gets the value for a given time field.
* @param field the given time field.
* @return the value for the given time field.
* @stable ICU 2.0
*/
public final int get(int field) {
return calendar.get(field);
}
/**
* Sets the time field with the given value.
* @param field the given time field.
* @param value the value to be set for the given time field.
* @stable ICU 2.0
*/
public final void set(int field, int value) {
calendar.set(field, value);
}
/**
* Sets the values for the fields year, month, and date.
* Previous values of other fields are retained. If this is not desired,
* call <code>clear</code> first.
* @param year the value used to set the YEAR time field.
* @param month the value used to set the MONTH time field.
* Month value is 0-based. e.g., 0 for January.
* @param date the value used to set the DATE time field.
* @stable ICU 2.0
*/
public final void set(int year, int month, int date) {
calendar.set(year, month, date);
}
/**
* Sets the values for the fields year, month, date, hour, and minute.
* Previous values of other fields are retained. If this is not desired,
* call <code>clear</code> first.
* @param year the value used to set the YEAR time field.
* @param month the value used to set the MONTH time field.
* Month value is 0-based. e.g., 0 for January.
* @param date the value used to set the DATE time field.
* @param hour the value used to set the HOUR_OF_DAY time field.
* @param minute the value used to set the MINUTE time field.
* @stable ICU 2.0
*/
public final void set(int year, int month, int date, int hour, int minute) {
calendar.set(year, month, date, hour, minute);
}
/**
* Sets the values for the fields year, month, date, hour, minute, and second.
* Previous values of other fields are retained. If this is not desired,
* call <code>clear</code> first.
* @param year the value used to set the YEAR time field.
* @param month the value used to set the MONTH time field.
* Month value is 0-based. e.g., 0 for January.
* @param date the value used to set the DATE time field.
* @param hour the value used to set the HOUR_OF_DAY time field.
* @param minute the value used to set the MINUTE time field.
* @param second the value used to set the SECOND time field.
* @stable ICU 2.0
*/
public final void set(int year, int month, int date, int hour, int minute, int second) {
calendar.set(year, month, date, hour, minute, second);
}
/**
* Clears the values of all the time fields.
* @stable ICU 2.0
*/
public final void clear() {
calendar.clear();
}
/**
* Clears the value in the given time field.
* @param field the time field to be cleared.
* @stable ICU 2.0
*/
public final void clear(int field) {
calendar.clear(field);
}
/**
* Determines if the given time field has a value set.
* @return true if the given time field has a value set; false otherwise.
* @stable ICU 2.0
*/
public final boolean isSet(int field) {
return calendar.isSet(field);
}
/**
* Compares this calendar to the specified object.
* The result is <code>true</code> if and only if the argument is
* not <code>null</code> and is a <code>Calendar</code> object that
* represents the same calendar as this object.
* @param obj the object to compare with.
* @return <code>true</code> if the objects are the same;
* <code>false</code> otherwise.
* @stable ICU 2.0
*/
public boolean equals(Object obj) {
try {
return calendar.equals(((Calendar)obj).calendar);
}
catch (Exception e) {
return false;
}
}
/**
* Returns true if the given Calendar object is equivalent to this
* one. An equivalent Calendar will behave exactly as this one
* does, but it may be set to a different time. By contrast, for
* the equals() method to return true, the other Calendar must
* be set to the same time.
*
* @param other the Calendar to be compared with this Calendar
* @stable ICU 2.4
*/
public boolean isEquivalentTo(Calendar other) {
return this.getClass() == other.getClass() &&
isLenient() == other.isLenient() &&
getFirstDayOfWeek() == other.getFirstDayOfWeek() &&
getMinimalDaysInFirstWeek() == other.getMinimalDaysInFirstWeek() &&
getTimeZone().equals(other.getTimeZone());
}
/**
* Returns a hash code for this calendar.
* @return a hash code value for this object.
* @stable ICU 2.0
*/
public int hashCode() {
return calendar.hashCode();
}
/**
* Return the difference in milliseconds between the moment this
* calendar is set to and the moment the given calendar or Date object
* is set to.
*/
private long compare(Object that) {
long thatMs;
if (that instanceof Calendar) {
thatMs = ((Calendar)that).getTimeInMillis();
} else if (that instanceof Date) {
thatMs = ((Date)that).getTime();
} else {
throw new IllegalArgumentException(that + "is not a Calendar or Date");
}
return getTimeInMillis() - thatMs;
}
/**
* Compares the time field records.
* Equivalent to comparing result of conversion to UTC.
* @param when the Calendar to be compared with this Calendar.
* @return true if the current time of this Calendar is before
* the time of Calendar when; false otherwise.
* @stable ICU 2.0
*/
public boolean before(Object when) {
return compare(when) < 0;
}
/**
* Compares the time field records.
* Equivalent to comparing result of conversion to UTC.
* @param when the Calendar to be compared with this Calendar.
* @return true if the current time of this Calendar is after
* the time of Calendar when; false otherwise.
* @stable ICU 2.0
*/
public boolean after(Object when) {
return compare(when) > 0;
}
/**
* Return the maximum value that this field could have, given the
* current date. For example, with the Gregorian date February 3, 1997
* and the {@link #DAY_OF_MONTH DAY_OF_MONTH} field, the actual maximum
* is 28; for February 3, 1996 it is 29.
*
* <p>The actual maximum computation ignores smaller fields and the
* current value of like-sized fields. For example, the actual maximum
* of the DAY_OF_YEAR or MONTH depends only on the year and supra-year
* fields. The actual maximum of the DAY_OF_MONTH depends, in
* addition, on the MONTH field and any other fields at that
* granularity (such as ChineseCalendar.IS_LEAP_MONTH). The
* DAY_OF_WEEK_IN_MONTH field does not depend on the current
* DAY_OF_WEEK; it returns the maximum for any day of week in the
* current month. Likewise for the WEEK_OF_MONTH and WEEK_OF_YEAR
* fields.
*
* @param field the field whose maximum is desired
* @return the maximum of the given field for the current date of this calendar
* @see #getMaximum
* @see #getLeastMaximum
* @stable ICU 2.0
*/
public int getActualMaximum(int field) {
return calendar.getActualMaximum(field);
}
/**
* Return the minimum value that this field could have, given the current date.
* For most fields, this is the same as {@link #getMinimum getMinimum}
* and {@link #getGreatestMinimum getGreatestMinimum}. However, some fields,
* especially those related to week number, are more complicated.
* <p>
* For example, assume {@link #getMinimalDaysInFirstWeek getMinimalDaysInFirstWeek}
* returns 4 and {@link #getFirstDayOfWeek getFirstDayOfWeek} returns SUNDAY.
* If the first day of the month is Sunday, Monday, Tuesday, or Wednesday
* there will be four or more days in the first week, so it will be week number 1,
* and <code>getActualMinimum(WEEK_OF_MONTH)</code> will return 1. However,
* if the first of the month is a Thursday, Friday, or Saturday, there are
* <em>not</em> four days in that week, so it is week number 0, and
* <code>getActualMinimum(WEEK_OF_MONTH)</code> will return 0.
* <p>
* @param field the field whose actual minimum value is desired.
* @return the minimum of the given field for the current date of this calendar
*
* @see #getMinimum
* @see #getGreatestMinimum
* @stable ICU 2.0
*/
public int getActualMinimum(int field) {
return calendar.getActualMinimum(field);
}
/**
* Rolls (up/down) a single unit of time on the given field. If the
* field is rolled past its maximum allowable value, it will "wrap" back
* to its minimum and continue rolling. For
* example, to roll the current date up by one day, you can call:
* <p>
* <code>roll({@link #DATE}, true)</code>
* <p>
* When rolling on the {@link #YEAR} field, it will roll the year
* value in the range between 1 and the value returned by calling
* {@link #getMaximum getMaximum}({@link #YEAR}).
* <p>
* When rolling on certain fields, the values of other fields may conflict and
* need to be changed. For example, when rolling the <code>MONTH</code> field
* for the Gregorian date 1/31/96 upward, the <code>DAY_OF_MONTH</code> field
* must be adjusted so that the result is 2/29/96 rather than the invalid
* 2/31/96.
* <p>
* <b>Note:</b> Calling <tt>roll(field, true)</tt> N times is <em>not</em>
* necessarily equivalent to calling <tt>roll(field, N)</tt>. For example,
* imagine that you start with the date Gregorian date January 31, 1995. If you call
* <tt>roll(Calendar.MONTH, 2)</tt>, the result will be March 31, 1995.
* But if you call <tt>roll(Calendar.MONTH, true)</tt>, the result will be
* February 28, 1995. Calling it one more time will give March 28, 1995, which
* is usually not the desired result.
* <p>
* <b>Note:</b> You should always use <tt>roll</tt> and <tt>add</tt> rather
* than attempting to perform arithmetic operations directly on the fields
* of a <tt>Calendar</tt>. It is quite possible for <tt>Calendar</tt> subclasses
* to have fields with non-linear behavior, for example missing months
* or days during non-leap years. The subclasses' <tt>add</tt> and <tt>roll</tt>
* methods will take this into account, while simple arithmetic manipulations
* may give invalid results.
* <p>
* @param field the calendar field to roll.
*
* @param up indicates if the value of the specified time field is to be
* rolled up or rolled down. Use <code>true</code> if rolling up,
* <code>false</code> otherwise.
*
* @exception IllegalArgumentException if the field is invalid or refers
* to a field that cannot be handled by this method.
* @see #roll(int, int)
* @see #add
* @stable ICU 2.0
*/
public final void roll(int field, boolean up) {
calendar.roll(field, up);
}
/**
* Rolls (up/down) a specified amount time on the given field. For
* example, to roll the current date up by three days, you can call
* <code>roll(Calendar.DATE, 3)</code>. If the
* field is rolled past its maximum allowable value, it will "wrap" back
* to its minimum and continue rolling.
* For example, calling <code>roll(Calendar.DATE, 10)</code>
* on a Gregorian calendar set to 4/25/96 will result in the date 4/5/96.
* <p>
* When rolling on certain fields, the values of other fields may conflict and
* need to be changed. For example, when rolling the {@link #MONTH MONTH} field
* for the Gregorian date 1/31/96 by +1, the {@link #DAY_OF_MONTH DAY_OF_MONTH} field
* must be adjusted so that the result is 2/29/96 rather than the invalid
* 2/31/96.
* <p>
* The <code>com.ibm.icu.util.Calendar</code> implementation of this method is able to roll
* all fields except for {@link #ERA ERA}, {@link #DST_OFFSET DST_OFFSET},
* and {@link #ZONE_OFFSET ZONE_OFFSET}. Subclasses may, of course, add support for
* additional fields in their overrides of <code>roll</code>.
* <p>
* <b>Note:</b> You should always use <tt>roll</tt> and <tt>add</tt> rather
* than attempting to perform arithmetic operations directly on the fields
* of a <tt>Calendar</tt>. It is quite possible for <tt>Calendar</tt> subclasses
* to have fields with non-linear behavior, for example missing months
* or days during non-leap years. The subclasses' <tt>add</tt> and <tt>roll</tt>
* methods will take this into account, while simple arithmetic manipulations
* may give invalid results.
* <p>
* <b>Subclassing:</b><br>
* This implementation of <code>roll</code> assumes that the behavior of the
* field is continuous between its minimum and maximum, which are found by
* calling {@link #getActualMinimum getActualMinimum} and {@link #getActualMaximum getActualMaximum}.
* For most such fields, simple addition, subtraction, and modulus operations
* are sufficient to perform the roll. For week-related fields,
* the results of {@link #getFirstDayOfWeek getFirstDayOfWeek} and
* {@link #getMinimalDaysInFirstWeek getMinimalDaysInFirstWeek} are also necessary.
* Subclasses can override these two methods if their values differ from the defaults.
* <p>
* Subclasses that have fields for which the assumption of continuity breaks
* down must overide <code>roll</code> to handle those fields specially.
* For example, in the Hebrew calendar the month "Adar I"
* only occurs in leap years; in other years the calendar jumps from
* Shevat (month #4) to Adar (month #6). The
* {@link HebrewCalendar#roll HebrewCalendar.roll} method takes this into account,
* so that rolling the month of Shevat by one gives the proper result (Adar) in a
* non-leap year.
* <p>
* @param field the calendar field to roll.
* @param amount the amount by which the field should be rolled.
*
* @exception IllegalArgumentException if the field is invalid or refers
* to a field that cannot be handled by this method.
* @see #roll(int, boolean)
* @see #add
* @stable ICU 2.0
*/
public void roll(int field, int amount) {
calendar.roll(field, amount);
}
/**
* Add a signed amount to a specified field, using this calendar's rules.
* For example, to add three days to the current date, you can call
* <code>add(Calendar.DATE, 3)</code>.
* <p>
* When adding to certain fields, the values of other fields may conflict and
* need to be changed. For example, when adding one to the {@link #MONTH MONTH} field
* for the Gregorian date 1/31/96, the {@link #DAY_OF_MONTH DAY_OF_MONTH} field
* must be adjusted so that the result is 2/29/96 rather than the invalid
* 2/31/96.
* <p>
* The <code>com.ibm.icu.util.Calendar</code> implementation of this method is able to add to
* all fields except for {@link #ERA ERA}, {@link #DST_OFFSET DST_OFFSET},
* and {@link #ZONE_OFFSET ZONE_OFFSET}. Subclasses may, of course, add support for
* additional fields in their overrides of <code>add</code>.
* <p>
* <b>Note:</b> You should always use <tt>roll</tt> and <tt>add</tt> rather
* than attempting to perform arithmetic operations directly on the fields
* of a <tt>Calendar</tt>. It is quite possible for <tt>Calendar</tt> subclasses
* to have fields with non-linear behavior, for example missing months
* or days during non-leap years. The subclasses' <tt>add</tt> and <tt>roll</tt>
* methods will take this into account, while simple arithmetic manipulations
* may give invalid results.
* <p>
* <b>Subclassing:</b><br>
* This implementation of <code>add</code> assumes that the behavior of the
* field is continuous between its minimum and maximum, which are found by
* calling {@link #getActualMinimum getActualMinimum} and
* {@link #getActualMaximum getActualMaximum}.
* For such fields, simple arithmetic operations are sufficient to
* perform the add.
* <p>
* Subclasses that have fields for which this assumption of continuity breaks
* down must overide <code>add</code> to handle those fields specially.
* For example, in the Hebrew calendar the month "Adar I"
* only occurs in leap years; in other years the calendar jumps from
* Shevat (month #4) to Adar (month #6). The
* {@link HebrewCalendar#add HebrewCalendar.add} method takes this into account,
* so that adding one month
* to a date in Shevat gives the proper result (Adar) in a non-leap year.
* <p>
* @param field the time field.
* @param amount the amount to add to the field.
*
* @exception IllegalArgumentException if the field is invalid or refers
* to a field that cannot be handled by this method.
* @see #roll(int, int)
* @stable ICU 2.0
*/
public void add(int field, int amount) {
calendar.add(field, amount);
}
/**
* Return the name of this calendar in the language of the given locale.
* @stable ICU 2.0
*/
public String getDisplayName(Locale loc) {
return "Calendar";
}
/**
* Return the name of this calendar in the language of the given locale.
* @stable ICU 3.2
*/
public String getDisplayName(ULocale loc) {
return "Calendar";
}
/**
* Compares the times (in millis) represented by two
* <code>Calendar</code> objects.
*
* @param that the <code>Calendar</code> to compare to this.
* @return <code>0</code> if the time represented by
* this <code>Calendar</code> is equal to the time represented
* by that <code>Calendar</code>, a value less than
* <code>0</code> if the time represented by this is before
* the time represented by that, and a value greater than
* <code>0</code> if the time represented by this
* is after the time represented by that.
* @throws NullPointerException if that
* <code>Calendar</code> is null.
* @throws IllegalArgumentException if the time of that
* <code>Calendar</code> can't be obtained because of invalid
* calendar values.
* @stable ICU 3.4
*/
public int compareTo(Calendar that) {
long v = getTimeInMillis() - that.getTimeInMillis();
return v < 0 ? -1 : (v > 0 ? 1 : 0);
}
/**
* Implement comparable API as a convenience override of
* {@link #compareTo(Calendar)}.
* @stable ICU 3.4
*/
public int compareTo(Object that) {
return compareTo((Calendar)that);
}
//-------------------------------------------------------------------------
// Interface for creating custon DateFormats for different types of Calendars
//-------------------------------------------------------------------------
/**
* Return a <code>DateFormat</code> appropriate to this calendar.
* @stable ICU 2.0
*/
public DateFormat getDateTimeFormat(int dateStyle, int timeStyle, Locale loc) {
return formatHelper(this, loc, dateStyle, timeStyle);
}
/**
* Return a <code>DateFormat</code> appropriate to this calendar.
* @stable ICU 3.2
*/
public DateFormat getDateTimeFormat(int dateStyle, int timeStyle, ULocale loc) {
return formatHelper(this, loc.toLocale(), dateStyle, timeStyle);
}
/*
* Utility for formatting.
*/
private static DateFormat formatHelper(Calendar cal, Locale loc, int dateStyle, int timeStyle) {
// Assume there is only one kind of calendar. In Java 6 there will also be Japanese
// calendars, but we'll worry about that when it happens.
DateFormat df = DateFormat.getDateTimeInstance(dateStyle, timeStyle, loc);
df.setCalendar(cal);
return df;
}
//-------------------------------------------------------------------------
// Constants
//-------------------------------------------------------------------------
/**
* [NEW]
* Return the difference between the given time and the time this
* calendar object is set to. If this calendar is set
* <em>before</em> the given time, the returned value will be
* positive. If this calendar is set <em>after</em> the given
* time, the returned value will be negative. The
* <code>field</code> parameter specifies the units of the return
* value. For example, if <code>fieldDifference(when,
* Calendar.MONTH)</code> returns 3, then this calendar is set to
* 3 months before <code>when</code>, and possibly some additional
* time less than one month.
*
* <p>As a side effect of this call, this calendar is advanced
* toward <code>when</code> by the given amount. That is, calling
* this method has the side effect of calling <code>add(field,
* n)</code>, where <code>n</code> is the return value.
*
* <p>Usage: To use this method, call it first with the largest
* field of interest, then with progressively smaller fields. For
* example:
*
* <pre>
* int y = cal.fieldDifference(when, Calendar.YEAR);
* int m = cal.fieldDifference(when, Calendar.MONTH);
* int d = cal.fieldDifference(when, Calendar.DATE);</pre>
*
* computes the difference between <code>cal</code> and
* <code>when</code> in years, months, and days.
*
* <p>Note: <code>fieldDifference()</code> is
* <em>asymmetrical</em>. That is, in the following code:
*
* <pre>
* cal.setTime(date1);
* int m1 = cal.fieldDifference(date2, Calendar.MONTH);
* int d1 = cal.fieldDifference(date2, Calendar.DATE);
* cal.setTime(date2);
* int m2 = cal.fieldDifference(date1, Calendar.MONTH);
* int d2 = cal.fieldDifference(date1, Calendar.DATE);</pre>
*
* one might expect that <code>m1 == -m2 && d1 == -d2</code>.
* However, this is not generally the case, because of
* irregularities in the underlying calendar system (e.g., the
* Gregorian calendar has a varying number of days per month).
*
* @param when the date to compare this calendar's time to
* @param field the field in which to compute the result
* @return the difference, either positive or negative, between
* this calendar's time and <code>when</code>, in terms of
* <code>field</code>.
* @stable ICU 2.0
*/
public int fieldDifference(Date when, int field) {
int min = 0;
long startMs = getTimeInMillis();
long targetMs = when.getTime();
// Always add from the start millis. This accomodates
// operations like adding years from February 29, 2000 up to
// February 29, 2004. If 1, 1, 1, 1 is added to the year
// field, the DOM gets pinned to 28 and stays there, giving an
// incorrect DOM difference of 1. We have to add 1, reset, 2,
// reset, 3, reset, 4.
if (startMs < targetMs) {
int max = 1;
// Find a value that is too large
for (;;) {
setTimeInMillis(startMs);
add(field, max);
long ms = getTimeInMillis();
if (ms == targetMs) {
return max;
} else if (ms > targetMs) {
break;
} else {
max <<= 1;
if (max < 0) {
// Field difference too large to fit into int
throw new RuntimeException();
}
}
}
// Do a binary search
while ((max - min) > 1) {
int t = (min + max) / 2;
setTimeInMillis(startMs);
add(field, t);
long ms = getTimeInMillis();
if (ms == targetMs) {
return t;
} else if (ms > targetMs) {
max = t;
} else {
min = t;
}
}
} else if (startMs > targetMs) {
if (false) {
// This works, and makes the code smaller, but costs
// an extra object creation and an extra couple cycles
// of calendar computation.
setTimeInMillis(targetMs);
min = -fieldDifference(new Date(startMs), field);
}
int max = -1;
// Find a value that is too small
for (;;) {
setTimeInMillis(startMs);
add(field, max);
long ms = getTimeInMillis();
if (ms == targetMs) {
return max;
} else if (ms < targetMs) {
break;
} else {
max <<= 1;
if (max == 0) {
// Field difference too large to fit into int
throw new RuntimeException();
}
}
}
// Do a binary search
while ((min - max) > 1) {
int t = (min + max) / 2;
setTimeInMillis(startMs);
add(field, t);
long ms = getTimeInMillis();
if (ms == targetMs) {
return t;
} else if (ms < targetMs) {
max = t;
} else {
min = t;
}
}
}
// Set calendar to end point
setTimeInMillis(startMs);
add(field, min);
return min;
}
/**
* Sets the time zone with the given time zone value.
* @param value the given time zone.
* @stable ICU 2.0
*/
public void setTimeZone(TimeZone value) {
calendar.setTimeZone(value.timeZone);
}
/**
* Gets the time zone.
* @return the time zone object associated with this calendar.
* @stable ICU 2.0
*/
public TimeZone getTimeZone() {
return new TimeZone(calendar.getTimeZone());
}
/**
* Specify whether or not date/time interpretation is to be lenient. With
* lenient interpretation, a date such as "February 942, 1996" will be
* treated as being equivalent to the 941st day after February 1, 1996.
* With strict interpretation, such dates will cause an exception to be
* thrown.
*
* @see DateFormat#setLenient
* @stable ICU 2.0
*/
public void setLenient(boolean lenient) {
calendar.setLenient(lenient);
}
/**
* Tell whether date/time interpretation is to be lenient.
* @stable ICU 2.0
*/
public boolean isLenient() {
return calendar.isLenient();
}
/**
* Sets what the first day of the week is; e.g., Sunday in US,
* Monday in France.
* @param value the given first day of the week.
* @stable ICU 2.0
*/
public void setFirstDayOfWeek(int value) {
calendar.setFirstDayOfWeek(value);
}
/**
* Gets what the first day of the week is; e.g., Sunday in US,
* Monday in France.
* @return the first day of the week.
* @stable ICU 2.0
*/
public int getFirstDayOfWeek() {
return calendar.getFirstDayOfWeek();
}
/**
* Sets what the minimal days required in the first week of the year are.
* For example, if the first week is defined as one that contains the first
* day of the first month of a year, call the method with value 1. If it
* must be a full week, use value 7.
* @param value the given minimal days required in the first week
* of the year.
* @stable ICU 2.0
*/
public void setMinimalDaysInFirstWeek(int value) {
calendar.setMinimalDaysInFirstWeek(value);
}
/**
* Gets what the minimal days required in the first week of the year are;
* e.g., if the first week is defined as one that contains the first day
* of the first month of a year, getMinimalDaysInFirstWeek returns 1. If
* the minimal days required must be a full week, getMinimalDaysInFirstWeek
* returns 7.
* @return the minimal days required in the first week of the year.
* @stable ICU 2.0
*/
public int getMinimalDaysInFirstWeek() {
return calendar.getMinimalDaysInFirstWeek();
}
/**
* Gets the minimum value for the given time field.
* e.g., for Gregorian DAY_OF_MONTH, 1.
* @param field the given time field.
* @return the minimum value for the given time field.
* @stable ICU 2.0
*/
public final int getMinimum(int field) {
return calendar.getMinimum(field);
}
/**
* Gets the maximum value for the given time field.
* e.g. for Gregorian DAY_OF_MONTH, 31.
* @param field the given time field.
* @return the maximum value for the given time field.
* @stable ICU 2.0
*/
public final int getMaximum(int field) {
return calendar.getMaximum(field);
}
/**
* Gets the highest minimum value for the given field if varies.
* Otherwise same as getMinimum(). For Gregorian, no difference.
* @param field the given time field.
* @return the highest minimum value for the given time field.
* @stable ICU 2.0
*/
public final int getGreatestMinimum(int field) {
return calendar.getGreatestMinimum(field);
}
/**
* Gets the lowest maximum value for the given field if varies.
* Otherwise same as getMaximum(). e.g., for Gregorian DAY_OF_MONTH, 28.
* @param field the given time field.
* @return the lowest maximum value for the given time field.
* @stable ICU 2.0
*/
public final int getLeastMaximum(int field) {
return calendar.getLeastMaximum(field);
}
//-------------------------------------------------------------------------
// Weekend support -- determining which days of the week are the weekend
// in a given locale
//-------------------------------------------------------------------------
/**
* Return whether the given day of the week is a weekday, a
* weekend day, or a day that transitions from one to the other,
* in this calendar system. If a transition occurs at midnight,
* then the days before and after the transition will have the
* type WEEKDAY or WEEKEND. If a transition occurs at a time
* other than midnight, then the day of the transition will have
* the type WEEKEND_ONSET or WEEKEND_CEASE. In this case, the
* method getWeekendTransition() will return the point of
* transition.
* @param dayOfWeek either SUNDAY, MONDAY, TUESDAY, WEDNESDAY,
* THURSDAY, FRIDAY, or SATURDAY
* @return either WEEKDAY, WEEKEND, WEEKEND_ONSET, or
* WEEKEND_CEASE
* @exception IllegalArgumentException if dayOfWeek is not
* between SUNDAY and SATURDAY, inclusive
* @see #WEEKDAY
* @see #WEEKEND
* @see #WEEKEND_ONSET
* @see #WEEKEND_CEASE
* @see #getWeekendTransition
* @see #isWeekend(Date)
* @see #isWeekend()
* @stable ICU 2.0
*/
public int getDayOfWeekType(int dayOfWeek) {
// weekend always full saturday and sunday
if (dayOfWeek < 1 || dayOfWeek > 7) {
throw new IllegalArgumentException("illegal day of week: " + dayOfWeek);
}
return dayOfWeek >= SATURDAY ? WEEKEND : WEEKDAY;
}
/**
* Return the time during the day at which the weekend begins or end in
* this calendar system. If getDayOfWeekType(dayOfWeek) ==
* WEEKEND_ONSET return the time at which the weekend begins. If
* getDayOfWeekType(dayOfWeek) == WEEKEND_CEASE return the time at
* which the weekend ends. If getDayOfWeekType(dayOfWeek) has some
* other value, then throw an exception.
* @param dayOfWeek either SUNDAY, MONDAY, TUESDAY, WEDNESDAY,
* THURSDAY, FRIDAY, or SATURDAY
* @return the milliseconds after midnight at which the
* weekend begins or ends
* @exception IllegalArgumentException if dayOfWeek is not
* WEEKEND_ONSET or WEEKEND_CEASE
* @see #getDayOfWeekType
* @see #isWeekend(Date)
* @see #isWeekend()
* @stable ICU 2.0
*/
public int getWeekendTransition(int dayOfWeek) {
throw new IllegalArgumentException("Not weekend transition day");
}
/**
* Return true if the given date and time is in the weekend in
* this calendar system. Equivalent to calling setTime() followed
* by isWeekend(). Note: This method changes the time this
* calendar is set to.
* @param date the date and time
* @return true if the given date and time is part of the
* weekend
* @see #getDayOfWeekType
* @see #getWeekendTransition
* @see #isWeekend()
* @stable ICU 2.0
*/
public boolean isWeekend(Date date) {
calendar.setTime(date);
return isWeekend();
}
/**
* Return true if this Calendar's current date and time is in the
* weekend in this calendar system.
* @return true if the given date and time is part of the
* weekend
* @see #getDayOfWeekType
* @see #getWeekendTransition
* @see #isWeekend(Date)
* @stable ICU 2.0
*/
public boolean isWeekend() {
return calendar.get(Calendar.DAY_OF_WEEK) >= SATURDAY;
}
//-------------------------------------------------------------------------
// End of weekend support
//-------------------------------------------------------------------------
/**
* Overrides Cloneable
* @stable ICU 2.0
*/
public Object clone() {
return new Calendar((java.util.Calendar)calendar.clone());
}
/**
* Return a string representation of this calendar. This method
* is intended to be used only for debugging purposes, and the
* format of the returned string may vary between implementations.
* The returned string may be empty but may not be <code>null</code>.
*
* @return a string representation of this calendar.
* @stable ICU 2.0
*/
public String toString() {
return calendar.toString();
}
/**
* Return the current Calendar type.
* Note, in 3.0 this function will return 'gregorian' in Calendar to emulate legacy behavior
* @return type of calendar (gregorian, etc)
* @internal ICU 3.0
*/
public String getType() {
return "gregorian";
}
}