View Javadoc
1   /*
2    * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4    *
5    * This code is free software; you can redistribute it and/or modify it
6    * under the terms of the GNU General Public License version 2 only, as
7    * published by the Free Software Foundation.  Oracle designates this
8    * particular file as subject to the "Classpath" exception as provided
9    * by Oracle in the LICENSE file that accompanied this code.
10   *
11   * This code is distributed in the hope that it will be useful, but WITHOUT
12   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14   * version 2 for more details (a copy is included in the LICENSE file that
15   * accompanied this code).
16   *
17   * You should have received a copy of the GNU General Public License version
18   * 2 along with this work; if not, write to the Free Software Foundation,
19   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20   *
21   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22   * or visit www.oracle.com if you need additional information or have any
23   * questions.
24   */
25  
26  /*
27   * (C) Copyright Taligent, Inc. 1996 - All Rights Reserved
28   * (C) Copyright IBM Corp. 1996 - All Rights Reserved
29   *
30   *   The original version of this source code and documentation is copyrighted
31   * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These
32   * materials are provided under terms of a License Agreement between Taligent
33   * and Sun. This technology is protected by multiple US and International
34   * patents. This notice and attribution to Taligent may not be removed.
35   *   Taligent is a registered trademark of Taligent, Inc.
36   *
37   */
38  
39  package java.text;
40  
41  import java.io.InvalidObjectException;
42  import java.text.spi.DateFormatProvider;
43  import java.util.Calendar;
44  import java.util.Date;
45  import java.util.GregorianCalendar;
46  import java.util.HashMap;
47  import java.util.Locale;
48  import java.util.Map;
49  import java.util.MissingResourceException;
50  import java.util.ResourceBundle;
51  import java.util.TimeZone;
52  import java.util.spi.LocaleServiceProvider;
53  import sun.util.locale.provider.LocaleProviderAdapter;
54  import sun.util.locale.provider.LocaleServiceProviderPool;
55  
56  /**
57   * {@code DateFormat} is an abstract class for date/time formatting subclasses which
58   * formats and parses dates or time in a language-independent manner.
59   * The date/time formatting subclass, such as {@link SimpleDateFormat}, allows for
60   * formatting (i.e., date → text), parsing (text → date), and
61   * normalization.  The date is represented as a <code>Date</code> object or
62   * as the milliseconds since January 1, 1970, 00:00:00 GMT.
63   *
64   * <p>{@code DateFormat} provides many class methods for obtaining default date/time
65   * formatters based on the default or a given locale and a number of formatting
66   * styles. The formatting styles include {@link #FULL}, {@link #LONG}, {@link #MEDIUM}, and {@link #SHORT}. More
67   * detail and examples of using these styles are provided in the method
68   * descriptions.
69   *
70   * <p>{@code DateFormat} helps you to format and parse dates for any locale.
71   * Your code can be completely independent of the locale conventions for
72   * months, days of the week, or even the calendar format: lunar vs. solar.
73   *
74   * <p>To format a date for the current Locale, use one of the
75   * static factory methods:
76   * <blockquote>
77   * <pre>{@code
78   * myString = DateFormat.getDateInstance().format(myDate);
79   * }</pre>
80   * </blockquote>
81   * <p>If you are formatting multiple dates, it is
82   * more efficient to get the format and use it multiple times so that
83   * the system doesn't have to fetch the information about the local
84   * language and country conventions multiple times.
85   * <blockquote>
86   * <pre>{@code
87   * DateFormat df = DateFormat.getDateInstance();
88   * for (int i = 0; i < myDate.length; ++i) {
89   *     output.println(df.format(myDate[i]) + "; ");
90   * }
91   * }</pre>
92   * </blockquote>
93   * <p>To format a date for a different Locale, specify it in the
94   * call to {@link #getDateInstance(int, Locale) getDateInstance()}.
95   * <blockquote>
96   * <pre>{@code
97   * DateFormat df = DateFormat.getDateInstance(DateFormat.LONG, Locale.FRANCE);
98   * }</pre>
99   * </blockquote>
100  * <p>You can use a DateFormat to parse also.
101  * <blockquote>
102  * <pre>{@code
103  * myDate = df.parse(myString);
104  * }</pre>
105  * </blockquote>
106  * <p>Use {@code getDateInstance} to get the normal date format for that country.
107  * There are other static factory methods available.
108  * Use {@code getTimeInstance} to get the time format for that country.
109  * Use {@code getDateTimeInstance} to get a date and time format. You can pass in
110  * different options to these factory methods to control the length of the
111  * result; from {@link #SHORT} to {@link #MEDIUM} to {@link #LONG} to {@link #FULL}. The exact result depends
112  * on the locale, but generally:
113  * <ul><li>{@link #SHORT} is completely numeric, such as {@code 12.13.52} or {@code 3:30pm}
114  * <li>{@link #MEDIUM} is longer, such as {@code Jan 12, 1952}
115  * <li>{@link #LONG} is longer, such as {@code January 12, 1952} or {@code 3:30:32pm}
116  * <li>{@link #FULL} is pretty completely specified, such as
117  * {@code Tuesday, April 12, 1952 AD or 3:30:42pm PST}.
118  * </ul>
119  *
120  * <p>You can also set the time zone on the format if you wish.
121  * If you want even more control over the format or parsing,
122  * (or want to give your users more control),
123  * you can try casting the {@code DateFormat} you get from the factory methods
124  * to a {@link SimpleDateFormat}. This will work for the majority
125  * of countries; just remember to put it in a {@code try} block in case you
126  * encounter an unusual one.
127  *
128  * <p>You can also use forms of the parse and format methods with
129  * {@link ParsePosition} and {@link FieldPosition} to
130  * allow you to
131  * <ul><li>progressively parse through pieces of a string.
132  * <li>align any particular field, or find out where it is for selection
133  * on the screen.
134  * </ul>
135  *
136  * <h3><a name="synchronization">Synchronization</a></h3>
137  *
138  * <p>
139  * Date formats are not synchronized.
140  * It is recommended to create separate format instances for each thread.
141  * If multiple threads access a format concurrently, it must be synchronized
142  * externally.
143  *
144  * @see          Format
145  * @see          NumberFormat
146  * @see          SimpleDateFormat
147  * @see          java.util.Calendar
148  * @see          java.util.GregorianCalendar
149  * @see          java.util.TimeZone
150  * @author       Mark Davis, Chen-Lieh Huang, Alan Liu
151  */
152 public abstract class DateFormat extends Format {
153 
154     /**
155      * The {@link Calendar} instance used for calculating the date-time fields
156      * and the instant of time. This field is used for both formatting and
157      * parsing.
158      *
159      * <p>Subclasses should initialize this field to a {@link Calendar}
160      * appropriate for the {@link Locale} associated with this
161      * <code>DateFormat</code>.
162      * @serial
163      */
164     protected Calendar calendar;
165 
166     /**
167      * The number formatter that <code>DateFormat</code> uses to format numbers
168      * in dates and times.  Subclasses should initialize this to a number format
169      * appropriate for the locale associated with this <code>DateFormat</code>.
170      * @serial
171      */
172     protected NumberFormat numberFormat;
173 
174     /**
175      * Useful constant for ERA field alignment.
176      * Used in FieldPosition of date/time formatting.
177      */
178     public final static int ERA_FIELD = 0;
179     /**
180      * Useful constant for YEAR field alignment.
181      * Used in FieldPosition of date/time formatting.
182      */
183     public final static int YEAR_FIELD = 1;
184     /**
185      * Useful constant for MONTH field alignment.
186      * Used in FieldPosition of date/time formatting.
187      */
188     public final static int MONTH_FIELD = 2;
189     /**
190      * Useful constant for DATE field alignment.
191      * Used in FieldPosition of date/time formatting.
192      */
193     public final static int DATE_FIELD = 3;
194     /**
195      * Useful constant for one-based HOUR_OF_DAY field alignment.
196      * Used in FieldPosition of date/time formatting.
197      * HOUR_OF_DAY1_FIELD is used for the one-based 24-hour clock.
198      * For example, 23:59 + 01:00 results in 24:59.
199      */
200     public final static int HOUR_OF_DAY1_FIELD = 4;
201     /**
202      * Useful constant for zero-based HOUR_OF_DAY field alignment.
203      * Used in FieldPosition of date/time formatting.
204      * HOUR_OF_DAY0_FIELD is used for the zero-based 24-hour clock.
205      * For example, 23:59 + 01:00 results in 00:59.
206      */
207     public final static int HOUR_OF_DAY0_FIELD = 5;
208     /**
209      * Useful constant for MINUTE field alignment.
210      * Used in FieldPosition of date/time formatting.
211      */
212     public final static int MINUTE_FIELD = 6;
213     /**
214      * Useful constant for SECOND field alignment.
215      * Used in FieldPosition of date/time formatting.
216      */
217     public final static int SECOND_FIELD = 7;
218     /**
219      * Useful constant for MILLISECOND field alignment.
220      * Used in FieldPosition of date/time formatting.
221      */
222     public final static int MILLISECOND_FIELD = 8;
223     /**
224      * Useful constant for DAY_OF_WEEK field alignment.
225      * Used in FieldPosition of date/time formatting.
226      */
227     public final static int DAY_OF_WEEK_FIELD = 9;
228     /**
229      * Useful constant for DAY_OF_YEAR field alignment.
230      * Used in FieldPosition of date/time formatting.
231      */
232     public final static int DAY_OF_YEAR_FIELD = 10;
233     /**
234      * Useful constant for DAY_OF_WEEK_IN_MONTH field alignment.
235      * Used in FieldPosition of date/time formatting.
236      */
237     public final static int DAY_OF_WEEK_IN_MONTH_FIELD = 11;
238     /**
239      * Useful constant for WEEK_OF_YEAR field alignment.
240      * Used in FieldPosition of date/time formatting.
241      */
242     public final static int WEEK_OF_YEAR_FIELD = 12;
243     /**
244      * Useful constant for WEEK_OF_MONTH field alignment.
245      * Used in FieldPosition of date/time formatting.
246      */
247     public final static int WEEK_OF_MONTH_FIELD = 13;
248     /**
249      * Useful constant for AM_PM field alignment.
250      * Used in FieldPosition of date/time formatting.
251      */
252     public final static int AM_PM_FIELD = 14;
253     /**
254      * Useful constant for one-based HOUR field alignment.
255      * Used in FieldPosition of date/time formatting.
256      * HOUR1_FIELD is used for the one-based 12-hour clock.
257      * For example, 11:30 PM + 1 hour results in 12:30 AM.
258      */
259     public final static int HOUR1_FIELD = 15;
260     /**
261      * Useful constant for zero-based HOUR field alignment.
262      * Used in FieldPosition of date/time formatting.
263      * HOUR0_FIELD is used for the zero-based 12-hour clock.
264      * For example, 11:30 PM + 1 hour results in 00:30 AM.
265      */
266     public final static int HOUR0_FIELD = 16;
267     /**
268      * Useful constant for TIMEZONE field alignment.
269      * Used in FieldPosition of date/time formatting.
270      */
271     public final static int TIMEZONE_FIELD = 17;
272 
273     // Proclaim serial compatibility with 1.1 FCS
274     private static final long serialVersionUID = 7218322306649953788L;
275 
276     /**
277      * Overrides Format.
278      * Formats a time object into a time string. Examples of time objects
279      * are a time value expressed in milliseconds and a Date object.
280      * @param obj must be a Number or a Date.
281      * @param toAppendTo the string buffer for the returning time string.
282      * @return the string buffer passed in as toAppendTo, with formatted text appended.
283      * @param fieldPosition keeps track of the position of the field
284      * within the returned string.
285      * On input: an alignment field,
286      * if desired. On output: the offsets of the alignment field. For
287      * example, given a time text "1996.07.10 AD at 15:08:56 PDT",
288      * if the given fieldPosition is DateFormat.YEAR_FIELD, the
289      * begin index and end index of fieldPosition will be set to
290      * 0 and 4, respectively.
291      * Notice that if the same time field appears
292      * more than once in a pattern, the fieldPosition will be set for the first
293      * occurrence of that time field. For instance, formatting a Date to
294      * the time string "1 PM PDT (Pacific Daylight Time)" using the pattern
295      * "h a z (zzzz)" and the alignment field DateFormat.TIMEZONE_FIELD,
296      * the begin index and end index of fieldPosition will be set to
297      * 5 and 8, respectively, for the first occurrence of the timezone
298      * pattern character 'z'.
299      * @see java.text.Format
300      */
301     public final StringBuffer format(Object obj, StringBuffer toAppendTo,
302                                      FieldPosition fieldPosition)
303     {
304         if (obj instanceof Date)
305             return format( (Date)obj, toAppendTo, fieldPosition );
306         else if (obj instanceof Number)
307             return format( new Date(((Number)obj).longValue()),
308                           toAppendTo, fieldPosition );
309         else
310             throw new IllegalArgumentException("Cannot format given Object as a Date");
311     }
312 
313     /**
314      * Formats a Date into a date/time string.
315      * @param date a Date to be formatted into a date/time string.
316      * @param toAppendTo the string buffer for the returning date/time string.
317      * @param fieldPosition keeps track of the position of the field
318      * within the returned string.
319      * On input: an alignment field,
320      * if desired. On output: the offsets of the alignment field. For
321      * example, given a time text "1996.07.10 AD at 15:08:56 PDT",
322      * if the given fieldPosition is DateFormat.YEAR_FIELD, the
323      * begin index and end index of fieldPosition will be set to
324      * 0 and 4, respectively.
325      * Notice that if the same time field appears
326      * more than once in a pattern, the fieldPosition will be set for the first
327      * occurrence of that time field. For instance, formatting a Date to
328      * the time string "1 PM PDT (Pacific Daylight Time)" using the pattern
329      * "h a z (zzzz)" and the alignment field DateFormat.TIMEZONE_FIELD,
330      * the begin index and end index of fieldPosition will be set to
331      * 5 and 8, respectively, for the first occurrence of the timezone
332      * pattern character 'z'.
333      * @return the string buffer passed in as toAppendTo, with formatted text appended.
334      */
335     public abstract StringBuffer format(Date date, StringBuffer toAppendTo,
336                                         FieldPosition fieldPosition);
337 
338     /**
339      * Formats a Date into a date/time string.
340      * @param date the time value to be formatted into a time string.
341      * @return the formatted time string.
342      */
343     public final String format(Date date)
344     {
345         return format(date, new StringBuffer(),
346                       DontCareFieldPosition.INSTANCE).toString();
347     }
348 
349     /**
350      * Parses text from the beginning of the given string to produce a date.
351      * The method may not use the entire text of the given string.
352      * <p>
353      * See the {@link #parse(String, ParsePosition)} method for more information
354      * on date parsing.
355      *
356      * @param source A <code>String</code> whose beginning should be parsed.
357      * @return A <code>Date</code> parsed from the string.
358      * @exception ParseException if the beginning of the specified string
359      *            cannot be parsed.
360      */
361     public Date parse(String source) throws ParseException
362     {
363         ParsePosition pos = new ParsePosition(0);
364         Date result = parse(source, pos);
365         if (pos.index == 0)
366             throw new ParseException("Unparseable date: \"" + source + "\"" ,
367                 pos.errorIndex);
368         return result;
369     }
370 
371     /**
372      * Parse a date/time string according to the given parse position.  For
373      * example, a time text {@code "07/10/96 4:5 PM, PDT"} will be parsed into a {@code Date}
374      * that is equivalent to {@code Date(837039900000L)}.
375      *
376      * <p> By default, parsing is lenient: If the input is not in the form used
377      * by this object's format method but can still be parsed as a date, then
378      * the parse succeeds.  Clients may insist on strict adherence to the
379      * format by calling {@link #setLenient(boolean) setLenient(false)}.
380      *
381      * <p>This parsing operation uses the {@link #calendar} to produce
382      * a {@code Date}. As a result, the {@code calendar}'s date-time
383      * fields and the {@code TimeZone} value may have been
384      * overwritten, depending on subclass implementations. Any {@code
385      * TimeZone} value that has previously been set by a call to
386      * {@link #setTimeZone(java.util.TimeZone) setTimeZone} may need
387      * to be restored for further operations.
388      *
389      * @param source  The date/time string to be parsed
390      *
391      * @param pos   On input, the position at which to start parsing; on
392      *              output, the position at which parsing terminated, or the
393      *              start position if the parse failed.
394      *
395      * @return      A {@code Date}, or {@code null} if the input could not be parsed
396      */
397     public abstract Date parse(String source, ParsePosition pos);
398 
399     /**
400      * Parses text from a string to produce a <code>Date</code>.
401      * <p>
402      * The method attempts to parse text starting at the index given by
403      * <code>pos</code>.
404      * If parsing succeeds, then the index of <code>pos</code> is updated
405      * to the index after the last character used (parsing does not necessarily
406      * use all characters up to the end of the string), and the parsed
407      * date is returned. The updated <code>pos</code> can be used to
408      * indicate the starting point for the next call to this method.
409      * If an error occurs, then the index of <code>pos</code> is not
410      * changed, the error index of <code>pos</code> is set to the index of
411      * the character where the error occurred, and null is returned.
412      * <p>
413      * See the {@link #parse(String, ParsePosition)} method for more information
414      * on date parsing.
415      *
416      * @param source A <code>String</code>, part of which should be parsed.
417      * @param pos A <code>ParsePosition</code> object with index and error
418      *            index information as described above.
419      * @return A <code>Date</code> parsed from the string. In case of
420      *         error, returns null.
421      * @exception NullPointerException if <code>pos</code> is null.
422      */
423     public Object parseObject(String source, ParsePosition pos) {
424         return parse(source, pos);
425     }
426 
427     /**
428      * Constant for full style pattern.
429      */
430     public static final int FULL = 0;
431     /**
432      * Constant for long style pattern.
433      */
434     public static final int LONG = 1;
435     /**
436      * Constant for medium style pattern.
437      */
438     public static final int MEDIUM = 2;
439     /**
440      * Constant for short style pattern.
441      */
442     public static final int SHORT = 3;
443     /**
444      * Constant for default style pattern.  Its value is MEDIUM.
445      */
446     public static final int DEFAULT = MEDIUM;
447 
448     /**
449      * Gets the time formatter with the default formatting style
450      * for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
451      * <p>This is equivalent to calling
452      * {@link #getTimeInstance(int, Locale) getTimeInstance(DEFAULT,
453      *     Locale.getDefault(Locale.Category.FORMAT))}.
454      * @see java.util.Locale#getDefault(java.util.Locale.Category)
455      * @see java.util.Locale.Category#FORMAT
456      * @return a time formatter.
457      */
458     public final static DateFormat getTimeInstance()
459     {
460         return get(DEFAULT, 0, 1, Locale.getDefault(Locale.Category.FORMAT));
461     }
462 
463     /**
464      * Gets the time formatter with the given formatting style
465      * for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
466      * <p>This is equivalent to calling
467      * {@link #getTimeInstance(int, Locale) getTimeInstance(style,
468      *     Locale.getDefault(Locale.Category.FORMAT))}.
469      * @see java.util.Locale#getDefault(java.util.Locale.Category)
470      * @see java.util.Locale.Category#FORMAT
471      * @param style the given formatting style. For example,
472      * SHORT for "h:mm a" in the US locale.
473      * @return a time formatter.
474      */
475     public final static DateFormat getTimeInstance(int style)
476     {
477         return get(style, 0, 1, Locale.getDefault(Locale.Category.FORMAT));
478     }
479 
480     /**
481      * Gets the time formatter with the given formatting style
482      * for the given locale.
483      * @param style the given formatting style. For example,
484      * SHORT for "h:mm a" in the US locale.
485      * @param aLocale the given locale.
486      * @return a time formatter.
487      */
488     public final static DateFormat getTimeInstance(int style,
489                                                  Locale aLocale)
490     {
491         return get(style, 0, 1, aLocale);
492     }
493 
494     /**
495      * Gets the date formatter with the default formatting style
496      * for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
497      * <p>This is equivalent to calling
498      * {@link #getDateInstance(int, Locale) getDateInstance(DEFAULT,
499      *     Locale.getDefault(Locale.Category.FORMAT))}.
500      * @see java.util.Locale#getDefault(java.util.Locale.Category)
501      * @see java.util.Locale.Category#FORMAT
502      * @return a date formatter.
503      */
504     public final static DateFormat getDateInstance()
505     {
506         return get(0, DEFAULT, 2, Locale.getDefault(Locale.Category.FORMAT));
507     }
508 
509     /**
510      * Gets the date formatter with the given formatting style
511      * for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
512      * <p>This is equivalent to calling
513      * {@link #getDateInstance(int, Locale) getDateInstance(style,
514      *     Locale.getDefault(Locale.Category.FORMAT))}.
515      * @see java.util.Locale#getDefault(java.util.Locale.Category)
516      * @see java.util.Locale.Category#FORMAT
517      * @param style the given formatting style. For example,
518      * SHORT for "M/d/yy" in the US locale.
519      * @return a date formatter.
520      */
521     public final static DateFormat getDateInstance(int style)
522     {
523         return get(0, style, 2, Locale.getDefault(Locale.Category.FORMAT));
524     }
525 
526     /**
527      * Gets the date formatter with the given formatting style
528      * for the given locale.
529      * @param style the given formatting style. For example,
530      * SHORT for "M/d/yy" in the US locale.
531      * @param aLocale the given locale.
532      * @return a date formatter.
533      */
534     public final static DateFormat getDateInstance(int style,
535                                                  Locale aLocale)
536     {
537         return get(0, style, 2, aLocale);
538     }
539 
540     /**
541      * Gets the date/time formatter with the default formatting style
542      * for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
543      * <p>This is equivalent to calling
544      * {@link #getDateTimeInstance(int, int, Locale) getDateTimeInstance(DEFAULT,
545      *     DEFAULT, Locale.getDefault(Locale.Category.FORMAT))}.
546      * @see java.util.Locale#getDefault(java.util.Locale.Category)
547      * @see java.util.Locale.Category#FORMAT
548      * @return a date/time formatter.
549      */
550     public final static DateFormat getDateTimeInstance()
551     {
552         return get(DEFAULT, DEFAULT, 3, Locale.getDefault(Locale.Category.FORMAT));
553     }
554 
555     /**
556      * Gets the date/time formatter with the given date and time
557      * formatting styles for the default {@link java.util.Locale.Category#FORMAT FORMAT} locale.
558      * <p>This is equivalent to calling
559      * {@link #getDateTimeInstance(int, int, Locale) getDateTimeInstance(dateStyle,
560      *     timeStyle, Locale.getDefault(Locale.Category.FORMAT))}.
561      * @see java.util.Locale#getDefault(java.util.Locale.Category)
562      * @see java.util.Locale.Category#FORMAT
563      * @param dateStyle the given date formatting style. For example,
564      * SHORT for "M/d/yy" in the US locale.
565      * @param timeStyle the given time formatting style. For example,
566      * SHORT for "h:mm a" in the US locale.
567      * @return a date/time formatter.
568      */
569     public final static DateFormat getDateTimeInstance(int dateStyle,
570                                                        int timeStyle)
571     {
572         return get(timeStyle, dateStyle, 3, Locale.getDefault(Locale.Category.FORMAT));
573     }
574 
575     /**
576      * Gets the date/time formatter with the given formatting styles
577      * for the given locale.
578      * @param dateStyle the given date formatting style.
579      * @param timeStyle the given time formatting style.
580      * @param aLocale the given locale.
581      * @return a date/time formatter.
582      */
583     public final static DateFormat
584         getDateTimeInstance(int dateStyle, int timeStyle, Locale aLocale)
585     {
586         return get(timeStyle, dateStyle, 3, aLocale);
587     }
588 
589     /**
590      * Get a default date/time formatter that uses the SHORT style for both the
591      * date and the time.
592      *
593      * @return a date/time formatter
594      */
595     public final static DateFormat getInstance() {
596         return getDateTimeInstance(SHORT, SHORT);
597     }
598 
599     /**
600      * Returns an array of all locales for which the
601      * <code>get*Instance</code> methods of this class can return
602      * localized instances.
603      * The returned array represents the union of locales supported by the Java
604      * runtime and by installed
605      * {@link java.text.spi.DateFormatProvider DateFormatProvider} implementations.
606      * It must contain at least a <code>Locale</code> instance equal to
607      * {@link java.util.Locale#US Locale.US}.
608      *
609      * @return An array of locales for which localized
610      *         <code>DateFormat</code> instances are available.
611      */
612     public static Locale[] getAvailableLocales()
613     {
614         LocaleServiceProviderPool pool =
615             LocaleServiceProviderPool.getPool(DateFormatProvider.class);
616         return pool.getAvailableLocales();
617     }
618 
619     /**
620      * Set the calendar to be used by this date format.  Initially, the default
621      * calendar for the specified or default locale is used.
622      *
623      * <p>Any {@link java.util.TimeZone TimeZone} and {@linkplain
624      * #isLenient() leniency} values that have previously been set are
625      * overwritten by {@code newCalendar}'s values.
626      *
627      * @param newCalendar the new {@code Calendar} to be used by the date format
628      */
629     public void setCalendar(Calendar newCalendar)
630     {
631         this.calendar = newCalendar;
632     }
633 
634     /**
635      * Gets the calendar associated with this date/time formatter.
636      *
637      * @return the calendar associated with this date/time formatter.
638      */
639     public Calendar getCalendar()
640     {
641         return calendar;
642     }
643 
644     /**
645      * Allows you to set the number formatter.
646      * @param newNumberFormat the given new NumberFormat.
647      */
648     public void setNumberFormat(NumberFormat newNumberFormat)
649     {
650         this.numberFormat = newNumberFormat;
651     }
652 
653     /**
654      * Gets the number formatter which this date/time formatter uses to
655      * format and parse a time.
656      * @return the number formatter which this date/time formatter uses.
657      */
658     public NumberFormat getNumberFormat()
659     {
660         return numberFormat;
661     }
662 
663     /**
664      * Sets the time zone for the calendar of this {@code DateFormat} object.
665      * This method is equivalent to the following call.
666      * <blockquote><pre>{@code
667      * getCalendar().setTimeZone(zone)
668      * }</pre></blockquote>
669      *
670      * <p>The {@code TimeZone} set by this method is overwritten by a
671      * {@link #setCalendar(java.util.Calendar) setCalendar} call.
672      *
673      * <p>The {@code TimeZone} set by this method may be overwritten as
674      * a result of a call to the parse method.
675      *
676      * @param zone the given new time zone.
677      */
678     public void setTimeZone(TimeZone zone)
679     {
680         calendar.setTimeZone(zone);
681     }
682 
683     /**
684      * Gets the time zone.
685      * This method is equivalent to the following call.
686      * <blockquote><pre>{@code
687      * getCalendar().getTimeZone()
688      * }</pre></blockquote>
689      *
690      * @return the time zone associated with the calendar of DateFormat.
691      */
692     public TimeZone getTimeZone()
693     {
694         return calendar.getTimeZone();
695     }
696 
697     /**
698      * Specify whether or not date/time parsing is to be lenient.  With
699      * lenient parsing, the parser may use heuristics to interpret inputs that
700      * do not precisely match this object's format.  With strict parsing,
701      * inputs must match this object's format.
702      *
703      * <p>This method is equivalent to the following call.
704      * <blockquote><pre>{@code
705      * getCalendar().setLenient(lenient)
706      * }</pre></blockquote>
707      *
708      * <p>This leniency value is overwritten by a call to {@link
709      * #setCalendar(java.util.Calendar) setCalendar()}.
710      *
711      * @param lenient when {@code true}, parsing is lenient
712      * @see java.util.Calendar#setLenient(boolean)
713      */
714     public void setLenient(boolean lenient)
715     {
716         calendar.setLenient(lenient);
717     }
718 
719     /**
720      * Tell whether date/time parsing is to be lenient.
721      * This method is equivalent to the following call.
722      * <blockquote><pre>{@code
723      * getCalendar().isLenient()
724      * }</pre></blockquote>
725      *
726      * @return {@code true} if the {@link #calendar} is lenient;
727      *         {@code false} otherwise.
728      * @see java.util.Calendar#isLenient()
729      */
730     public boolean isLenient()
731     {
732         return calendar.isLenient();
733     }
734 
735     /**
736      * Overrides hashCode
737      */
738     public int hashCode() {
739         return numberFormat.hashCode();
740         // just enough fields for a reasonable distribution
741     }
742 
743     /**
744      * Overrides equals
745      */
746     public boolean equals(Object obj) {
747         if (this == obj) return true;
748         if (obj == null || getClass() != obj.getClass()) return false;
749         DateFormat other = (DateFormat) obj;
750         return (// calendar.equivalentTo(other.calendar) // THIS API DOESN'T EXIST YET!
751                 calendar.getFirstDayOfWeek() == other.calendar.getFirstDayOfWeek() &&
752                 calendar.getMinimalDaysInFirstWeek() == other.calendar.getMinimalDaysInFirstWeek() &&
753                 calendar.isLenient() == other.calendar.isLenient() &&
754                 calendar.getTimeZone().equals(other.calendar.getTimeZone()) &&
755                 numberFormat.equals(other.numberFormat));
756     }
757 
758     /**
759      * Overrides Cloneable
760      */
761     public Object clone()
762     {
763         DateFormat other = (DateFormat) super.clone();
764         other.calendar = (Calendar) calendar.clone();
765         other.numberFormat = (NumberFormat) numberFormat.clone();
766         return other;
767     }
768 
769     /**
770      * Creates a DateFormat with the given time and/or date style in the given
771      * locale.
772      * @param timeStyle a value from 0 to 3 indicating the time format,
773      * ignored if flags is 2
774      * @param dateStyle a value from 0 to 3 indicating the time format,
775      * ignored if flags is 1
776      * @param flags either 1 for a time format, 2 for a date format,
777      * or 3 for a date/time format
778      * @param loc the locale for the format
779      */
780     private static DateFormat get(int timeStyle, int dateStyle,
781                                   int flags, Locale loc) {
782         if ((flags & 1) != 0) {
783             if (timeStyle < 0 || timeStyle > 3) {
784                 throw new IllegalArgumentException("Illegal time style " + timeStyle);
785             }
786         } else {
787             timeStyle = -1;
788         }
789         if ((flags & 2) != 0) {
790             if (dateStyle < 0 || dateStyle > 3) {
791                 throw new IllegalArgumentException("Illegal date style " + dateStyle);
792             }
793         } else {
794             dateStyle = -1;
795         }
796 
797         LocaleProviderAdapter adapter = LocaleProviderAdapter.getAdapter(DateFormatProvider.class, loc);
798         DateFormat dateFormat = get(adapter, timeStyle, dateStyle, loc);
799         if (dateFormat == null) {
800             dateFormat = get(LocaleProviderAdapter.forJRE(), timeStyle, dateStyle, loc);
801         }
802         return dateFormat;
803     }
804 
805     private static DateFormat get(LocaleProviderAdapter adapter, int timeStyle, int dateStyle, Locale loc) {
806         DateFormatProvider provider = adapter.getDateFormatProvider();
807         DateFormat dateFormat;
808         if (timeStyle == -1) {
809             dateFormat = provider.getDateInstance(dateStyle, loc);
810         } else {
811             if (dateStyle == -1) {
812                 dateFormat = provider.getTimeInstance(timeStyle, loc);
813             } else {
814                 dateFormat = provider.getDateTimeInstance(dateStyle, timeStyle, loc);
815             }
816         }
817         return dateFormat;
818     }
819 
820     /**
821      * Create a new date format.
822      */
823     protected DateFormat() {}
824 
825     /**
826      * Defines constants that are used as attribute keys in the
827      * <code>AttributedCharacterIterator</code> returned
828      * from <code>DateFormat.formatToCharacterIterator</code> and as
829      * field identifiers in <code>FieldPosition</code>.
830      * <p>
831      * The class also provides two methods to map
832      * between its constants and the corresponding Calendar constants.
833      *
834      * @since 1.4
835      * @see java.util.Calendar
836      */
837     public static class Field extends Format.Field {
838 
839         // Proclaim serial compatibility with 1.4 FCS
840         private static final long serialVersionUID = 7441350119349544720L;
841 
842         // table of all instances in this class, used by readResolve
843         private static final Map<String, Field> instanceMap = new HashMap<>(18);
844         // Maps from Calendar constant (such as Calendar.ERA) to Field
845         // constant (such as Field.ERA).
846         private static final Field[] calendarToFieldMapping =
847                                              new Field[Calendar.FIELD_COUNT];
848 
849         /** Calendar field. */
850         private int calendarField;
851 
852         /**
853          * Returns the <code>Field</code> constant that corresponds to
854          * the <code>Calendar</code> constant <code>calendarField</code>.
855          * If there is no direct mapping between the <code>Calendar</code>
856          * constant and a <code>Field</code>, null is returned.
857          *
858          * @throws IllegalArgumentException if <code>calendarField</code> is
859          *         not the value of a <code>Calendar</code> field constant.
860          * @param calendarField Calendar field constant
861          * @return Field instance representing calendarField.
862          * @see java.util.Calendar
863          */
864         public static Field ofCalendarField(int calendarField) {
865             if (calendarField < 0 || calendarField >=
866                         calendarToFieldMapping.length) {
867                 throw new IllegalArgumentException("Unknown Calendar constant "
868                                                    + calendarField);
869             }
870             return calendarToFieldMapping[calendarField];
871         }
872 
873         /**
874          * Creates a <code>Field</code>.
875          *
876          * @param name the name of the <code>Field</code>
877          * @param calendarField the <code>Calendar</code> constant this
878          *        <code>Field</code> corresponds to; any value, even one
879          *        outside the range of legal <code>Calendar</code> values may
880          *        be used, but <code>-1</code> should be used for values
881          *        that don't correspond to legal <code>Calendar</code> values
882          */
883         protected Field(String name, int calendarField) {
884             super(name);
885             this.calendarField = calendarField;
886             if (this.getClass() == DateFormat.Field.class) {
887                 instanceMap.put(name, this);
888                 if (calendarField >= 0) {
889                     // assert(calendarField < Calendar.FIELD_COUNT);
890                     calendarToFieldMapping[calendarField] = this;
891                 }
892             }
893         }
894 
895         /**
896          * Returns the <code>Calendar</code> field associated with this
897          * attribute. For example, if this represents the hours field of
898          * a <code>Calendar</code>, this would return
899          * <code>Calendar.HOUR</code>. If there is no corresponding
900          * <code>Calendar</code> constant, this will return -1.
901          *
902          * @return Calendar constant for this field
903          * @see java.util.Calendar
904          */
905         public int getCalendarField() {
906             return calendarField;
907         }
908 
909         /**
910          * Resolves instances being deserialized to the predefined constants.
911          *
912          * @throws InvalidObjectException if the constant could not be
913          *         resolved.
914          * @return resolved DateFormat.Field constant
915          */
916         @Override
917         protected Object readResolve() throws InvalidObjectException {
918             if (this.getClass() != DateFormat.Field.class) {
919                 throw new InvalidObjectException("subclass didn't correctly implement readResolve");
920             }
921 
922             Object instance = instanceMap.get(getName());
923             if (instance != null) {
924                 return instance;
925             } else {
926                 throw new InvalidObjectException("unknown attribute name");
927             }
928         }
929 
930         //
931         // The constants
932         //
933 
934         /**
935          * Constant identifying the era field.
936          */
937         public final static Field ERA = new Field("era", Calendar.ERA);
938 
939         /**
940          * Constant identifying the year field.
941          */
942         public final static Field YEAR = new Field("year", Calendar.YEAR);
943 
944         /**
945          * Constant identifying the month field.
946          */
947         public final static Field MONTH = new Field("month", Calendar.MONTH);
948 
949         /**
950          * Constant identifying the day of month field.
951          */
952         public final static Field DAY_OF_MONTH = new
953                             Field("day of month", Calendar.DAY_OF_MONTH);
954 
955         /**
956          * Constant identifying the hour of day field, where the legal values
957          * are 1 to 24.
958          */
959         public final static Field HOUR_OF_DAY1 = new Field("hour of day 1",-1);
960 
961         /**
962          * Constant identifying the hour of day field, where the legal values
963          * are 0 to 23.
964          */
965         public final static Field HOUR_OF_DAY0 = new
966                Field("hour of day", Calendar.HOUR_OF_DAY);
967 
968         /**
969          * Constant identifying the minute field.
970          */
971         public final static Field MINUTE =new Field("minute", Calendar.MINUTE);
972 
973         /**
974          * Constant identifying the second field.
975          */
976         public final static Field SECOND =new Field("second", Calendar.SECOND);
977 
978         /**
979          * Constant identifying the millisecond field.
980          */
981         public final static Field MILLISECOND = new
982                 Field("millisecond", Calendar.MILLISECOND);
983 
984         /**
985          * Constant identifying the day of week field.
986          */
987         public final static Field DAY_OF_WEEK = new
988                 Field("day of week", Calendar.DAY_OF_WEEK);
989 
990         /**
991          * Constant identifying the day of year field.
992          */
993         public final static Field DAY_OF_YEAR = new
994                 Field("day of year", Calendar.DAY_OF_YEAR);
995 
996         /**
997          * Constant identifying the day of week field.
998          */
999         public final static Field DAY_OF_WEEK_IN_MONTH =
1000                      new Field("day of week in month",
1001                                             Calendar.DAY_OF_WEEK_IN_MONTH);
1002 
1003         /**
1004          * Constant identifying the week of year field.
1005          */
1006         public final static Field WEEK_OF_YEAR = new
1007               Field("week of year", Calendar.WEEK_OF_YEAR);
1008 
1009         /**
1010          * Constant identifying the week of month field.
1011          */
1012         public final static Field WEEK_OF_MONTH = new
1013             Field("week of month", Calendar.WEEK_OF_MONTH);
1014 
1015         /**
1016          * Constant identifying the time of day indicator
1017          * (e.g. "a.m." or "p.m.") field.
1018          */
1019         public final static Field AM_PM = new
1020                             Field("am pm", Calendar.AM_PM);
1021 
1022         /**
1023          * Constant identifying the hour field, where the legal values are
1024          * 1 to 12.
1025          */
1026         public final static Field HOUR1 = new Field("hour 1", -1);
1027 
1028         /**
1029          * Constant identifying the hour field, where the legal values are
1030          * 0 to 11.
1031          */
1032         public final static Field HOUR0 = new
1033                             Field("hour", Calendar.HOUR);
1034 
1035         /**
1036          * Constant identifying the time zone field.
1037          */
1038         public final static Field TIME_ZONE = new Field("time zone", -1);
1039     }
1040 }