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1 /*
2  * Copyright (C) 2006 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package android.text.format;
18 
19 import android.annotation.NonNull;
20 import android.app.compat.CompatChanges;
21 import android.compat.annotation.ChangeId;
22 import android.compat.annotation.EnabledSince;
23 import android.compat.annotation.UnsupportedAppUsage;
24 import android.content.Context;
25 import android.icu.text.DateFormatSymbols;
26 import android.icu.text.DateTimePatternGenerator;
27 import android.os.Build;
28 import android.provider.Settings;
29 import android.text.SpannableStringBuilder;
30 import android.text.Spanned;
31 import android.text.SpannedString;
32 import android.text.TextUtils;
33 
34 import java.text.SimpleDateFormat;
35 import java.util.Calendar;
36 import java.util.Date;
37 import java.util.GregorianCalendar;
38 import java.util.Locale;
39 import java.util.TimeZone;
40 
41 /**
42  * Utility class for producing strings with formatted date/time.
43  *
44  * <p>Most callers should avoid supplying their own format strings to this
45  * class' {@code format} methods and rely on the correctly localized ones
46  * supplied by the system. This class' factory methods return
47  * appropriately-localized {@link java.text.DateFormat} instances, suitable
48  * for both formatting and parsing dates. For the canonical documentation
49  * of format strings, see {@link java.text.SimpleDateFormat}.
50  *
51  * <p>In cases where the system does not provide a suitable pattern,
52  * this class offers the {@link #getBestDateTimePattern} method.
53  *
54  * <p>The {@code format} methods in this class implement a subset of Unicode
55  * <a href="http://www.unicode.org/reports/tr35/#Date_Format_Patterns">UTS #35</a> patterns.
56  * The subset currently supported by this class includes the following format characters:
57  * {@code acdEHhLKkLMmsyz}. Up to API level 17, only {@code adEhkMmszy} were supported.
58  * Note that this class incorrectly implements {@code k} as if it were {@code H} for backwards
59  * compatibility.
60  *
61  * <p>See {@link java.text.SimpleDateFormat} for more documentation
62  * about patterns, or if you need a more complete or correct implementation.
63  * Note that the non-{@code format} methods in this class are implemented by
64  * {@code SimpleDateFormat}.
65  */
66 public class DateFormat {
67     /**
68      * @deprecated Use a literal {@code '} instead.
69      * @removed
70      */
71     @Deprecated
72     public  static final char    QUOTE                  =    '\'';
73 
74     /**
75      * @deprecated Use a literal {@code 'a'} instead.
76      * @removed
77      */
78     @Deprecated
79     public  static final char    AM_PM                  =    'a';
80 
81     /**
82      * @deprecated Use a literal {@code 'a'} instead; 'A' was always equivalent to 'a'.
83      * @removed
84      */
85     @Deprecated
86     public  static final char    CAPITAL_AM_PM          =    'A';
87 
88     /**
89      * @deprecated Use a literal {@code 'd'} instead.
90      * @removed
91      */
92     @Deprecated
93     public  static final char    DATE                   =    'd';
94 
95     /**
96      * @deprecated Use a literal {@code 'E'} instead.
97      * @removed
98      */
99     @Deprecated
100     public  static final char    DAY                    =    'E';
101 
102     /**
103      * @deprecated Use a literal {@code 'h'} instead.
104      * @removed
105      */
106     @Deprecated
107     public  static final char    HOUR                   =    'h';
108 
109     /**
110      * @deprecated Use a literal {@code 'H'} (for compatibility with {@link SimpleDateFormat}
111      * and Unicode) or {@code 'k'} (for compatibility with Android releases up to and including
112      * Jelly Bean MR-1) instead. Note that the two are incompatible.
113      *
114      * @removed
115      */
116     @Deprecated
117     public  static final char    HOUR_OF_DAY            =    'k';
118 
119     /**
120      * @deprecated Use a literal {@code 'm'} instead.
121      * @removed
122      */
123     @Deprecated
124     public  static final char    MINUTE                 =    'm';
125 
126     /**
127      * @deprecated Use a literal {@code 'M'} instead.
128      * @removed
129      */
130     @Deprecated
131     public  static final char    MONTH                  =    'M';
132 
133     /**
134      * @deprecated Use a literal {@code 'L'} instead.
135      * @removed
136      */
137     @Deprecated
138     public  static final char    STANDALONE_MONTH       =    'L';
139 
140     /**
141      * @deprecated Use a literal {@code 's'} instead.
142      * @removed
143      */
144     @Deprecated
145     public  static final char    SECONDS                =    's';
146 
147     /**
148      * @deprecated Use a literal {@code 'z'} instead.
149      * @removed
150      */
151     @Deprecated
152     public  static final char    TIME_ZONE              =    'z';
153 
154     /**
155      * @deprecated Use a literal {@code 'y'} instead.
156      * @removed
157      */
158     @Deprecated
159     public  static final char    YEAR                   =    'y';
160 
161 
162     private static final Object sLocaleLock = new Object();
163     private static Locale sIs24HourLocale;
164     private static boolean sIs24Hour;
165 
166     /**
167      * {@link #getBestDateTimePattern(Locale, String)} does not allow non-consecutive repeated
168      * symbol in the skeleton. For example, please use a skeleton of {@code "jmm"} or
169      * {@code "hmma"} instead of {@code "ahmma"} or {@code "jmma"}, because the field 'j' could
170      * mean using 12-hour in some locales and, in this case, is duplicated as the 'a' field.
171      */
172     @ChangeId
173     @EnabledSince(targetSdkVersion = Build.VERSION_CODES.CUR_DEVELOPMENT)
174     static final long DISALLOW_DUPLICATE_FIELD_IN_SKELETON = 170233598L;
175 
176     /**
177      * Returns true if times should be formatted as 24 hour times, false if times should be
178      * formatted as 12 hour (AM/PM) times. Based on the user's chosen locale and other preferences.
179      * @param context the context to use for the content resolver
180      * @return true if 24 hour time format is selected, false otherwise.
181      */
is24HourFormat(Context context)182     public static boolean is24HourFormat(Context context) {
183         return is24HourFormat(context, context.getUserId());
184     }
185 
186     /**
187      * Returns true if times should be formatted as 24 hour times, false if times should be
188      * formatted as 12 hour (AM/PM) times. Based on the user's chosen locale and other preferences.
189      * @param context the context to use for the content resolver
190      * @param userHandle the user handle of the user to query.
191      * @return true if 24 hour time format is selected, false otherwise.
192      *
193      * @hide
194      */
195     @UnsupportedAppUsage
is24HourFormat(Context context, int userHandle)196     public static boolean is24HourFormat(Context context, int userHandle) {
197         final String value = Settings.System.getStringForUser(context.getContentResolver(),
198                 Settings.System.TIME_12_24, userHandle);
199         if (value != null) {
200             return value.equals("24");
201         }
202 
203         return is24HourLocale(context.getResources().getConfiguration().locale);
204     }
205 
206     /**
207      * Returns true if the specified locale uses a 24-hour time format by default, ignoring user
208      * settings.
209      * @param locale the locale to check
210      * @return true if the locale uses a 24 hour time format by default, false otherwise
211      * @hide
212      */
is24HourLocale(@onNull Locale locale)213     public static boolean is24HourLocale(@NonNull Locale locale) {
214         synchronized (sLocaleLock) {
215             if (sIs24HourLocale != null && sIs24HourLocale.equals(locale)) {
216                 return sIs24Hour;
217             }
218         }
219 
220         final java.text.DateFormat natural =
221                 java.text.DateFormat.getTimeInstance(java.text.DateFormat.LONG, locale);
222 
223         final boolean is24Hour;
224         if (natural instanceof SimpleDateFormat) {
225             final SimpleDateFormat sdf = (SimpleDateFormat) natural;
226             final String pattern = sdf.toPattern();
227             is24Hour = hasDesignator(pattern, 'H');
228         } else {
229             is24Hour = false;
230         }
231 
232         synchronized (sLocaleLock) {
233             sIs24HourLocale = locale;
234             sIs24Hour = is24Hour;
235         }
236 
237         return is24Hour;
238     }
239 
240     /**
241      * Returns the best possible localized form of the given skeleton for the given
242      * locale. A skeleton is similar to, and uses the same format characters as, a Unicode
243      * <a href="http://www.unicode.org/reports/tr35/#Date_Format_Patterns">UTS #35</a>
244      * pattern.
245      *
246      * <p>One difference is that order is irrelevant. For example, "MMMMd" will return
247      * "MMMM d" in the {@code en_US} locale, but "d. MMMM" in the {@code de_CH} locale.
248      *
249      * <p>Note also in that second example that the necessary punctuation for German was
250      * added. For the same input in {@code es_ES}, we'd have even more extra text:
251      * "d 'de' MMMM".
252      *
253      * <p>This method will automatically correct for grammatical necessity. Given the
254      * same "MMMMd" input, this method will return "d LLLL" in the {@code fa_IR} locale,
255      * where stand-alone months are necessary. Lengths are preserved where meaningful,
256      * so "Md" would give a different result to "MMMd", say, except in a locale such as
257      * {@code ja_JP} where there is only one length of month.
258      *
259      * <p>This method will only return patterns that are in CLDR, and is useful whenever
260      * you know what elements you want in your format string but don't want to make your
261      * code specific to any one locale.
262      *
263      * @param locale the locale into which the skeleton should be localized
264      * @param skeleton a skeleton as described above
265      * @return a string pattern suitable for use with {@link java.text.SimpleDateFormat}.
266      */
getBestDateTimePattern(Locale locale, String skeleton)267     public static String getBestDateTimePattern(Locale locale, String skeleton) {
268         DateTimePatternGenerator dtpg = DateTimePatternGenerator.getInstance(locale);
269         boolean allowDuplicateFields = !CompatChanges.isChangeEnabled(
270                 DISALLOW_DUPLICATE_FIELD_IN_SKELETON);
271         return dtpg.getBestPattern(skeleton, DateTimePatternGenerator.MATCH_NO_OPTIONS,
272                 allowDuplicateFields);
273     }
274 
275     /**
276      * Returns a {@link java.text.DateFormat} object that can format the time according
277      * to the context's locale and the user's 12-/24-hour clock preference.
278      * @param context the application context
279      * @return the {@link java.text.DateFormat} object that properly formats the time.
280      */
getTimeFormat(Context context)281     public static java.text.DateFormat getTimeFormat(Context context) {
282         final Locale locale = context.getResources().getConfiguration().locale;
283         return new java.text.SimpleDateFormat(getTimeFormatString(context), locale);
284     }
285 
286     /**
287      * Returns a String pattern that can be used to format the time according
288      * to the context's locale and the user's 12-/24-hour clock preference.
289      * @param context the application context
290      * @hide
291      */
292     @UnsupportedAppUsage
getTimeFormatString(Context context)293     public static String getTimeFormatString(Context context) {
294         return getTimeFormatString(context, context.getUserId());
295     }
296 
297     /**
298      * Returns a String pattern that can be used to format the time according
299      * to the context's locale and the user's 12-/24-hour clock preference.
300      * @param context the application context
301      * @param userHandle the user handle of the user to query the format for
302      * @hide
303      */
304     @UnsupportedAppUsage
getTimeFormatString(Context context, int userHandle)305     public static String getTimeFormatString(Context context, int userHandle) {
306         DateTimePatternGenerator dtpg = DateTimePatternGenerator.getInstance(
307                 context.getResources().getConfiguration().locale);
308         return is24HourFormat(context, userHandle) ? dtpg.getBestPattern("Hm")
309             : dtpg.getBestPattern("hm");
310     }
311 
312     /**
313      * Returns a {@link java.text.DateFormat} object that can format the date
314      * in short form according to the context's locale.
315      *
316      * @param context the application context
317      * @return the {@link java.text.DateFormat} object that properly formats the date.
318      */
getDateFormat(Context context)319     public static java.text.DateFormat getDateFormat(Context context) {
320         final Locale locale = context.getResources().getConfiguration().locale;
321         return java.text.DateFormat.getDateInstance(java.text.DateFormat.SHORT, locale);
322     }
323 
324     /**
325      * Returns a {@link java.text.DateFormat} object that can format the date
326      * in long form (such as {@code Monday, January 3, 2000}) for the context's locale.
327      * @param context the application context
328      * @return the {@link java.text.DateFormat} object that formats the date in long form.
329      */
getLongDateFormat(Context context)330     public static java.text.DateFormat getLongDateFormat(Context context) {
331         final Locale locale = context.getResources().getConfiguration().locale;
332         return java.text.DateFormat.getDateInstance(java.text.DateFormat.LONG, locale);
333     }
334 
335     /**
336      * Returns a {@link java.text.DateFormat} object that can format the date
337      * in medium form (such as {@code Jan 3, 2000}) for the context's locale.
338      * @param context the application context
339      * @return the {@link java.text.DateFormat} object that formats the date in long form.
340      */
getMediumDateFormat(Context context)341     public static java.text.DateFormat getMediumDateFormat(Context context) {
342         final Locale locale = context.getResources().getConfiguration().locale;
343         return java.text.DateFormat.getDateInstance(java.text.DateFormat.MEDIUM, locale);
344     }
345 
346     /**
347      * Gets the current date format stored as a char array. Returns a 3 element
348      * array containing the day ({@code 'd'}), month ({@code 'M'}), and year ({@code 'y'}))
349      * in the order specified by the user's format preference.  Note that this order is
350      * <i>only</i> appropriate for all-numeric dates; spelled-out (MEDIUM and LONG)
351      * dates will generally contain other punctuation, spaces, or words,
352      * not just the day, month, and year, and not necessarily in the same
353      * order returned here.
354      */
getDateFormatOrder(Context context)355     public static char[] getDateFormatOrder(Context context) {
356         return getDateFormatOrder(getDateFormatString(context));
357     }
358 
359     /**
360      * @hide Used by internal framework class {@link android.widget.DatePickerSpinnerDelegate}.
361      */
getDateFormatOrder(String pattern)362     public static char[] getDateFormatOrder(String pattern) {
363         char[] result = new char[3];
364         int resultIndex = 0;
365         boolean sawDay = false;
366         boolean sawMonth = false;
367         boolean sawYear = false;
368 
369         for (int i = 0; i < pattern.length(); ++i) {
370             char ch = pattern.charAt(i);
371             if (ch == 'd' || ch == 'L' || ch == 'M' || ch == 'y') {
372                 if (ch == 'd' && !sawDay) {
373                     result[resultIndex++] = 'd';
374                     sawDay = true;
375                 } else if ((ch == 'L' || ch == 'M') && !sawMonth) {
376                     result[resultIndex++] = 'M';
377                     sawMonth = true;
378                 } else if ((ch == 'y') && !sawYear) {
379                     result[resultIndex++] = 'y';
380                     sawYear = true;
381                 }
382             } else if (ch == 'G') {
383                 // Ignore the era specifier, if present.
384             } else if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')) {
385                 throw new IllegalArgumentException("Bad pattern character '" + ch + "' in "
386                     + pattern);
387             } else if (ch == '\'') {
388                 if (i < pattern.length() - 1 && pattern.charAt(i + 1) == '\'') {
389                     ++i;
390                 } else {
391                     i = pattern.indexOf('\'', i + 1);
392                     if (i == -1) {
393                         throw new IllegalArgumentException("Bad quoting in " + pattern);
394                     }
395                     ++i;
396                 }
397             } else {
398                 // Ignore spaces and punctuation.
399             }
400         }
401         return result;
402     }
403 
getDateFormatString(Context context)404     private static String getDateFormatString(Context context) {
405         final Locale locale = context.getResources().getConfiguration().locale;
406         java.text.DateFormat df = java.text.DateFormat.getDateInstance(
407                 java.text.DateFormat.SHORT, locale);
408         if (df instanceof SimpleDateFormat) {
409             return ((SimpleDateFormat) df).toPattern();
410         }
411 
412         throw new AssertionError("!(df instanceof SimpleDateFormat)");
413     }
414 
415     /**
416      * Given a format string and a time in milliseconds since Jan 1, 1970 GMT, returns a
417      * CharSequence containing the requested date.
418      * @param inFormat the format string, as described in {@link android.text.format.DateFormat}
419      * @param inTimeInMillis in milliseconds since Jan 1, 1970 GMT
420      * @return a {@link CharSequence} containing the requested text
421      */
format(CharSequence inFormat, long inTimeInMillis)422     public static CharSequence format(CharSequence inFormat, long inTimeInMillis) {
423         return format(inFormat, new Date(inTimeInMillis));
424     }
425 
426     /**
427      * Given a format string and a {@link java.util.Date} object, returns a CharSequence containing
428      * the requested date.
429      * @param inFormat the format string, as described in {@link android.text.format.DateFormat}
430      * @param inDate the date to format
431      * @return a {@link CharSequence} containing the requested text
432      */
format(CharSequence inFormat, Date inDate)433     public static CharSequence format(CharSequence inFormat, Date inDate) {
434         Calendar c = new GregorianCalendar();
435         c.setTime(inDate);
436         return format(inFormat, c);
437     }
438 
439     /**
440      * Indicates whether the specified format string contains seconds.
441      *
442      * Always returns false if the input format is null.
443      *
444      * @param inFormat the format string, as described in {@link android.text.format.DateFormat}
445      *
446      * @return true if the format string contains {@link #SECONDS}, false otherwise
447      *
448      * @hide
449      */
450     @UnsupportedAppUsage
hasSeconds(CharSequence inFormat)451     public static boolean hasSeconds(CharSequence inFormat) {
452         return hasDesignator(inFormat, SECONDS);
453     }
454 
455     /**
456      * Test if a format string contains the given designator. Always returns
457      * {@code false} if the input format is {@code null}.
458      *
459      * Note that this is intended for searching for designators, not arbitrary
460      * characters. So searching for a literal single quote would not work correctly.
461      *
462      * @hide
463      */
464     @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
hasDesignator(CharSequence inFormat, char designator)465     public static boolean hasDesignator(CharSequence inFormat, char designator) {
466         if (inFormat == null) return false;
467 
468         final int length = inFormat.length();
469 
470         boolean insideQuote = false;
471         for (int i = 0; i < length; i++) {
472             final char c = inFormat.charAt(i);
473             if (c == QUOTE) {
474                 insideQuote = !insideQuote;
475             } else if (!insideQuote) {
476                 if (c == designator) {
477                     return true;
478                 }
479             }
480         }
481 
482         return false;
483     }
484 
485     /**
486      * Given a format string and a {@link java.util.Calendar} object, returns a CharSequence
487      * containing the requested date.
488      * @param inFormat the format string, as described in {@link android.text.format.DateFormat}
489      * @param inDate the date to format
490      * @return a {@link CharSequence} containing the requested text
491      */
format(CharSequence inFormat, Calendar inDate)492     public static CharSequence format(CharSequence inFormat, Calendar inDate) {
493         SpannableStringBuilder s = new SpannableStringBuilder(inFormat);
494         int count;
495 
496         DateFormatSymbols dfs = getIcuDateFormatSymbols(Locale.getDefault());
497         String[] amPm = dfs.getAmPmStrings();
498 
499         int len = inFormat.length();
500 
501         for (int i = 0; i < len; i += count) {
502             count = 1;
503             int c = s.charAt(i);
504 
505             if (c == QUOTE) {
506                 count = appendQuotedText(s, i);
507                 len = s.length();
508                 continue;
509             }
510 
511             while ((i + count < len) && (s.charAt(i + count) == c)) {
512                 count++;
513             }
514 
515             String replacement;
516             switch (c) {
517                 case 'A':
518                 case 'a':
519                     replacement = amPm[inDate.get(Calendar.AM_PM) - Calendar.AM];
520                     break;
521                 case 'd':
522                     replacement = zeroPad(inDate.get(Calendar.DATE), count);
523                     break;
524                 case 'c':
525                 case 'E':
526                     replacement = getDayOfWeekString(dfs,
527                                                      inDate.get(Calendar.DAY_OF_WEEK), count, c);
528                     break;
529                 case 'K': // hour in am/pm (0-11)
530                 case 'h': // hour in am/pm (1-12)
531                     {
532                         int hour = inDate.get(Calendar.HOUR);
533                         if (c == 'h' && hour == 0) {
534                             hour = 12;
535                         }
536                         replacement = zeroPad(hour, count);
537                     }
538                     break;
539                 case 'H': // hour in day (0-23)
540                 case 'k': // hour in day (1-24) [but see note below]
541                     {
542                         int hour = inDate.get(Calendar.HOUR_OF_DAY);
543                         // Historically on Android 'k' was interpreted as 'H', which wasn't
544                         // implemented, so pretty much all callers that want to format 24-hour
545                         // times are abusing 'k'. http://b/8359981.
546                         if (false && c == 'k' && hour == 0) {
547                             hour = 24;
548                         }
549                         replacement = zeroPad(hour, count);
550                     }
551                     break;
552                 case 'L':
553                 case 'M':
554                     replacement = getMonthString(dfs, inDate.get(Calendar.MONTH), count, c);
555                     break;
556                 case 'm':
557                     replacement = zeroPad(inDate.get(Calendar.MINUTE), count);
558                     break;
559                 case 's':
560                     replacement = zeroPad(inDate.get(Calendar.SECOND), count);
561                     break;
562                 case 'y':
563                     replacement = getYearString(inDate.get(Calendar.YEAR), count);
564                     break;
565                 case 'z':
566                     replacement = getTimeZoneString(inDate, count);
567                     break;
568                 default:
569                     replacement = null;
570                     break;
571             }
572 
573             if (replacement != null) {
574                 s.replace(i, i + count, replacement);
575                 count = replacement.length(); // CARE: count is used in the for loop above
576                 len = s.length();
577             }
578         }
579 
580         if (inFormat instanceof Spanned) {
581             return new SpannedString(s);
582         } else {
583             return s.toString();
584         }
585     }
586 
getDayOfWeekString(DateFormatSymbols dfs, int day, int count, int kind)587     private static String getDayOfWeekString(DateFormatSymbols dfs, int day, int count, int kind) {
588         boolean standalone = (kind == 'c');
589         int context = standalone ? DateFormatSymbols.STANDALONE : DateFormatSymbols.FORMAT;
590         final int width;
591         if (count == 5) {
592             width = DateFormatSymbols.NARROW;
593         } else if (count == 4) {
594             width = DateFormatSymbols.WIDE;
595         } else {
596             width = DateFormatSymbols.ABBREVIATED;
597         }
598         return dfs.getWeekdays(context, width)[day];
599     }
600 
getMonthString(DateFormatSymbols dfs, int month, int count, int kind)601     private static String getMonthString(DateFormatSymbols dfs, int month, int count, int kind) {
602         boolean standalone = (kind == 'L');
603         int monthContext = standalone ? DateFormatSymbols.STANDALONE : DateFormatSymbols.FORMAT;
604         if (count == 5) {
605             return dfs.getMonths(monthContext, DateFormatSymbols.NARROW)[month];
606         } else if (count == 4) {
607             return dfs.getMonths(monthContext, DateFormatSymbols.WIDE)[month];
608         } else if (count == 3) {
609             return dfs.getMonths(monthContext, DateFormatSymbols.ABBREVIATED)[month];
610         } else {
611             // Calendar.JANUARY == 0, so add 1 to month.
612             return zeroPad(month+1, count);
613         }
614     }
615 
getTimeZoneString(Calendar inDate, int count)616     private static String getTimeZoneString(Calendar inDate, int count) {
617         TimeZone tz = inDate.getTimeZone();
618         if (count < 2) { // FIXME: shouldn't this be <= 2 ?
619             return formatZoneOffset(inDate.get(Calendar.DST_OFFSET) +
620                                     inDate.get(Calendar.ZONE_OFFSET),
621                                     count);
622         } else {
623             boolean dst = inDate.get(Calendar.DST_OFFSET) != 0;
624             return tz.getDisplayName(dst, TimeZone.SHORT);
625         }
626     }
627 
formatZoneOffset(int offset, int count)628     private static String formatZoneOffset(int offset, int count) {
629         offset /= 1000; // milliseconds to seconds
630         StringBuilder tb = new StringBuilder();
631 
632         if (offset < 0) {
633             tb.insert(0, "-");
634             offset = -offset;
635         } else {
636             tb.insert(0, "+");
637         }
638 
639         int hours = offset / 3600;
640         int minutes = (offset % 3600) / 60;
641 
642         tb.append(zeroPad(hours, 2));
643         tb.append(zeroPad(minutes, 2));
644         return tb.toString();
645     }
646 
getYearString(int year, int count)647     private static String getYearString(int year, int count) {
648         return (count <= 2) ? zeroPad(year % 100, 2)
649                             : String.format(Locale.getDefault(), "%d", year);
650     }
651 
652 
653     /**
654      * Strips quotation marks from the {@code formatString} and appends the result back to the
655      * {@code formatString}.
656      *
657      * @param formatString the format string, as described in
658      *                     {@link android.text.format.DateFormat}, to be modified
659      * @param index        index of the first quote
660      * @return the length of the quoted text that was appended.
661      * @hide
662      */
appendQuotedText(SpannableStringBuilder formatString, int index)663     public static int appendQuotedText(SpannableStringBuilder formatString, int index) {
664         int length = formatString.length();
665         if (index + 1 < length && formatString.charAt(index + 1) == QUOTE) {
666             formatString.delete(index, index + 1);
667             return 1;
668         }
669 
670         int count = 0;
671 
672         // delete leading quote
673         formatString.delete(index, index + 1);
674         length--;
675 
676         while (index < length) {
677             char c = formatString.charAt(index);
678 
679             if (c == QUOTE) {
680                 //  QUOTEQUOTE -> QUOTE
681                 if (index + 1 < length && formatString.charAt(index + 1) == QUOTE) {
682 
683                     formatString.delete(index, index + 1);
684                     length--;
685                     count++;
686                     index++;
687                 } else {
688                     //  Closing QUOTE ends quoted text copying
689                     formatString.delete(index, index + 1);
690                     break;
691                 }
692             } else {
693                 index++;
694                 count++;
695             }
696         }
697 
698         return count;
699     }
700 
zeroPad(int inValue, int inMinDigits)701     private static String zeroPad(int inValue, int inMinDigits) {
702         return String.format(Locale.getDefault(), "%0" + inMinDigits + "d", inValue);
703     }
704 
705     /**
706      * We use Gregorian calendar for date formats in android.text.format and various UI widget
707      * historically. It's a utility method to get an {@link DateFormatSymbols} instance. Note that
708      * {@link DateFormatSymbols} has cache, and external cache is not needed unless same instance is
709      * requested repeatedly in the performance critical code.
710      *
711      * @hide
712      */
getIcuDateFormatSymbols(Locale locale)713     public static DateFormatSymbols getIcuDateFormatSymbols(Locale locale) {
714         return new DateFormatSymbols(android.icu.util.GregorianCalendar.class, locale);
715     }
716 }
717