calendar.java

gcc的组建

/* Calendar.java --
   Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004, 2005  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version. */


package java.util;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;

/**
 * This class is an abstract base class for Calendars, which can be
 * used to convert between <code>Date</code> objects and a set of
 * integer fields which represent <code>YEAR</code>,
 * <code>MONTH</code>, <code>DAY</code>, etc.  The <code>Date</code>
 * object represents a time in milliseconds since the Epoch. <br>
 *
 * This class is locale sensitive.  To get the Object matching the
 * current locale you can use <code>getInstance</code>.  You can even provide
 * a locale or a timezone.  <code>getInstance</code> returns currently
 * a <code>GregorianCalendar</code> for the current date. <br>
 *
 * If you want to convert a date from the Year, Month, Day, DayOfWeek,
 * etc.  Representation to a <code>Date</code>-Object, you can create
 * a new Calendar with <code>getInstance()</code>,
 * <code>clear()</code> all fields, <code>set(int,int)</code> the
 * fields you need and convert it with <code>getTime()</code>. <br>
 *
 * If you want to convert a <code>Date</code>-object to the Calendar
 * representation, create a new Calendar, assign the
 * <code>Date</code>-Object with <code>setTime()</code>, and read the
 * fields with <code>get(int)</code>. <br>
 *
 * When computing the date from time fields, it may happen, that there
 * are either two few fields set, or some fields are inconsistent.  This
 * cases will handled in a calendar specific way.  Missing fields are
 * replaced by the fields of the epoch: 1970 January 1 00:00. <br>
 *
 * To understand, how the day of year is computed out of the fields
 * look at the following table.  It is traversed from top to bottom,
 * and for the first line all fields are set, that line is used to
 * compute the day. <br>
 *
 *
<pre>month + day_of_month
month + week_of_month + day_of_week
month + day_of_week_of_month + day_of_week
day_of_year
day_of_week + week_of_year</pre>
 *
 * The hour_of_day-field takes precedence over the ampm and
 * hour_of_ampm fields. <br>
 *
 * <STRONG>Note:</STRONG> This can differ for non-Gregorian calendar. <br>
 *
 * To convert a calendar to a human readable form and vice versa,  use
 * the <code>java.text.DateFormat</code> class. <br>
 *
 * Other useful things you can do with an calendar, is
 * <code>roll</code>ing fields (that means increase/decrease a
 * specific field by one, propagating overflows), or
 * <code>add</code>ing/substracting a fixed amount to a field.
 *
 * @see Date
 * @see GregorianCalendar
 * @see TimeZone
 * @see java.text.DateFormat
 */
public abstract class Calendar implements Serializable, Cloneable
{
  /**
   * Constant representing the era time field.
   */
  public static final int ERA = 0;

  /**
   * Constant representing the year time field.
   */
  public static final int YEAR = 1;

  /**
   * Constant representing the month time field.  This field
   * should contain one of the JANUARY,...,DECEMBER constants below.
   */
  public static final int MONTH = 2;

  /**
   * Constant representing the week of the year field.
   * @see #setFirstDayOfWeek(int)
   */
  public static final int WEEK_OF_YEAR = 3;

  /**
   * Constant representing the week of the month time field.
   * @see #setFirstDayOfWeek(int)
   */
  public static final int WEEK_OF_MONTH = 4;

  /**
   * Constant representing the day time field, synonym for DAY_OF_MONTH.
   */
  public static final int DATE = 5;

  /**
   * Constant representing the day time field.
   */
  public static final int DAY_OF_MONTH = 5;

  /**
   * Constant representing the day of year time field.  This is
   * 1 for the first day in month.
   */
  public static final int DAY_OF_YEAR = 6;

  /**
   * Constant representing the day of week time field.  This field
   * should contain one of the SUNDAY,...,SATURDAY constants below.
   */
  public static final int DAY_OF_WEEK = 7;

  /**
   * Constant representing the day-of-week-in-month field.  For
   * instance this field contains 2 for the second thursday in a
   * month.  If you give a negative number here, the day will count
   * from the end of the month.
   */
  public static final int DAY_OF_WEEK_IN_MONTH = 8;

  /**
   * Constant representing the part of the day for 12-hour clock.  This
   * should be one of AM or PM.
   */
  public static final int AM_PM = 9;

  /**
   * Constant representing the hour time field for 12-hour clock.
   */
  public static final int HOUR = 10;

  /**
   * Constant representing the hour of day time field for 24-hour clock.
   */
  public static final int HOUR_OF_DAY = 11;

  /**
   * Constant representing the minute of hour time field.
   */
  public static final int MINUTE = 12;

  /**
   * Constant representing the second time field.
   */
  public static final int SECOND = 13;

  /**
   * Constant representing the millisecond time field.
   */
  public static final int MILLISECOND = 14;

  /**
   * Constant representing the time zone offset time field for the
   * time given in the other fields.  It is measured in
   * milliseconds.  The default is the offset of the time zone.
   */
  public static final int ZONE_OFFSET = 15;

  /**
   * Constant representing the daylight saving time offset in
   * milliseconds.  The default is the value given by the time zone.
   */
  public static final int DST_OFFSET = 16;

  /**
   * Number of time fields.
   */
  public static final int FIELD_COUNT = 17;

  /**
   * Constant representing Sunday.
   */
  public static final int SUNDAY = 1;

  /**
   * Constant representing Monday.
   */
  public static final int MONDAY = 2;

  /**
   * Constant representing Tuesday.
   */
  public static final int TUESDAY = 3;

  /**
   * Constant representing Wednesday.
   */
  public static final int WEDNESDAY = 4;

  /**
   * Constant representing Thursday.
   */
  public static final int THURSDAY = 5;

  /**
   * Constant representing Friday.
   */
  public static final int FRIDAY = 6;

  /**
   * Constant representing Saturday.
   */
  public static final int SATURDAY = 7;

  /**
   * Constant representing January.
   */
  public static final int JANUARY = 0;

  /**
   * Constant representing February.
   */
  public static final int FEBRUARY = 1;

  /**
   * Constant representing March.
   */
  public static final int MARCH = 2;

  /**
   * Constant representing April.
   */
  public static final int APRIL = 3;

  /**
   * Constant representing May.
   */
  public static final int MAY = 4;

  /**
   * Constant representing June.
   */
  public static final int JUNE = 5;

  /**
   * Constant representing July.
   */
  public static final int JULY = 6;

  /**
   * Constant representing August.
   */
  public static final int AUGUST = 7;

  /**
   * Constant representing September.
   */
  public static final int SEPTEMBER = 8;

  /**
   * Constant representing October.
   */
  public static final int OCTOBER = 9;

  /**
   * Constant representing November.
   */
  public static final int NOVEMBER = 10;

  /**
   * Constant representing December.
   */
  public static final int DECEMBER = 11;

  /**
   * Constant representing Undecimber. This is an artificial name useful
   * for lunar calendars.
   */
  public static final int UNDECIMBER = 12;

  /**
   * Useful constant for 12-hour clock.
   */
  public static final int AM = 0;

  /**
   * Useful constant for 12-hour clock.
   */
  public static final int PM = 1;

  /**
   * The time fields.  The array is indexed by the constants YEAR to
   * DST_OFFSET.
   * @serial
   */
  protected int[] fields = new int[FIELD_COUNT];

  /**
   * The flags which tell if the fields above have a value.
   * @serial
   */
  protected boolean[] isSet = new boolean[FIELD_COUNT];

  /**
   * The time in milliseconds since the epoch.
   * @serial
   */
  protected long time;

  /**
   * Tells if the above field has a valid value.
   * @serial
   */
  protected boolean isTimeSet;

  /**
   * Tells if the fields have a valid value.  This superseeds the isSet
   * array.
   * @serial
   */
  protected boolean areFieldsSet;

  /**
   * The time zone of this calendar.  Used by sub classes to do UTC / local
   * time conversion.  Sub classes can access this field with getTimeZone().
   * @serial
   */
  private TimeZone zone;

  /**
   * Specifies if the date/time interpretation should be lenient.
   * If the flag is set, a date such as "February 30, 1996" will be
   * treated as the 29th day after the February 1.  If this flag
   * is false, such dates will cause an exception.
   * @serial
   */
  private boolean lenient;

  /**
   * Sets what the first day of week is.  This is used for
   * WEEK_OF_MONTH and WEEK_OF_YEAR fields.
   * @serial
   */
  private int firstDayOfWeek;

  /**
   * Sets how many days are required in the first week of the year.
   * If the first day of the year should be the first week you should
   * set this value to 1.  If the first week must be a full week, set
   * it to 7.
   * @serial
   */
  private int minimalDaysInFirstWeek;

  /**
   * Is set to true if DST_OFFSET is explicitly set. In that case
   * it's value overrides the value computed from the current
   * time and the timezone.
   */
  private boolean explicitDSTOffset = false;

  /**
   * The version of the serialized data on the stream.
   * <dl><dt>0 or not present</dt>
   * <dd> JDK 1.1.5 or later.</dd>
   * <dt>1</dt>
   * <dd>JDK 1.1.6 or later.  This always writes a correct `time' value
   * on the stream, as well as the other fields, to be compatible with
   * earlier versions</dd></dl>
   * @since JDK1.1.6
   * @serial
   */
  private int serialVersionOnStream = 1;

  /**
   * XXX - I have not checked the compatibility.  The documentation of
   * the serialized-form is quite hairy...
   */
  static final long serialVersionUID = -1807547505821590642L;

  /**
   * The name of the resource bundle. Used only by getBundle()
   */
  private static final String bundleName = "gnu.java.locale.Calendar";

  /**
   * get resource bundle:
   * The resources should be loaded via this method only. Iff an application
   * uses this method, the resourcebundle is required.
   */
  private static ResourceBundle getBundle(Locale locale)