/* | |
******************************************************************************* | |
* Copyright (C) 1996-2006, 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. | |
* @draft 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. | |
* @draft 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 | |
*/ | |
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. | |
* @draft 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. | |
* @draft 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)}. | |
* @draft 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. | |
* @draft 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"; | |
} | |
} | |