src/com/android/contacts/common/util/DateUtils.java - platform/packages/apps/ContactsCommon - Git at Google

 /*
  * Copyright (C) 2010 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package com.android.contacts.common.util;

 import android.content.Context;
 import android.text.format.DateFormat;


 import java.text.ParsePosition;
 import java.text.SimpleDateFormat;
 import java.util.Calendar;
 import java.util.Date;
 import java.util.GregorianCalendar;
 import java.util.Locale;
 import java.util.TimeZone;

 /**
  * Utility methods for processing dates.
  */
 public class DateUtils {
     public static final TimeZone UTC_TIMEZONE = TimeZone.getTimeZone("UTC");

     /**
      * When parsing a date without a year, the system assumes 1970, which wasn't a leap-year.
      * Let's add a one-off hack for that day of the year
      */
     public static final String NO_YEAR_DATE_FEB29TH = "--02-29";

     // Variations of ISO 8601 date format.  Do not change the order - it does affect the
     // result in ambiguous cases.
     private static final SimpleDateFormat[] DATE_FORMATS = {
         CommonDateUtils.FULL_DATE_FORMAT,
         CommonDateUtils.DATE_AND_TIME_FORMAT,
         new SimpleDateFormat("yyyy-MM-dd'T'HH:mm'Z'", Locale.US),
         new SimpleDateFormat("yyyyMMdd", Locale.US),
         new SimpleDateFormat("yyyyMMdd'T'HHmmssSSS'Z'", Locale.US),
         new SimpleDateFormat("yyyyMMdd'T'HHmmss'Z'", Locale.US),
         new SimpleDateFormat("yyyyMMdd'T'HHmm'Z'", Locale.US),
     };

     static {
         for (SimpleDateFormat format : DATE_FORMATS) {
             format.setLenient(true);
             format.setTimeZone(UTC_TIMEZONE);
         }
         CommonDateUtils.NO_YEAR_DATE_FORMAT.setTimeZone(UTC_TIMEZONE);
     }

     /**
      * Parses the supplied string to see if it looks like a date.
      *
      * @param string The string representation of the provided date
      * @param mustContainYear If true, the string is parsed as a date containing a year. If false,
      * the string is parsed into a valid date even if the year field is missing.
      * @return A Calendar object corresponding to the date if the string is successfully parsed.
      * If not, null is returned.
      */
     public static Calendar parseDate(String string, boolean mustContainYear) {
         ParsePosition parsePosition = new ParsePosition(0);
         Date date;
         if (!mustContainYear) {
             final boolean noYearParsed;
             // Unfortunately, we can't parse Feb 29th correctly, so let's handle this day seperately
             if (NO_YEAR_DATE_FEB29TH.equals(string)) {
                 return getUtcDate(0, Calendar.FEBRUARY, 29);
             } else {
                 synchronized (CommonDateUtils.NO_YEAR_DATE_FORMAT) {
                     date = CommonDateUtils.NO_YEAR_DATE_FORMAT.parse(string, parsePosition);
                 }
                 noYearParsed = parsePosition.getIndex() == string.length();
             }

             if (noYearParsed) {
                 return getUtcDate(date, true);
             }
         }
         for (int i = 0; i < DATE_FORMATS.length; i++) {
             SimpleDateFormat f = DATE_FORMATS[i];
             synchronized (f) {
                 parsePosition.setIndex(0);
                 date = f.parse(string, parsePosition);
                 if (parsePosition.getIndex() == string.length()) {
                     return getUtcDate(date, false);
                 }
             }
         }
         return null;
     }

     private static final Calendar getUtcDate(Date date, boolean noYear) {
         final Calendar calendar = Calendar.getInstance(UTC_TIMEZONE, Locale.US);
         calendar.setTime(date);
         if (noYear) {
             calendar.set(Calendar.YEAR, 0);
         }
         return calendar;
     }

     private static final Calendar getUtcDate(int year, int month, int dayOfMonth) {
         final Calendar calendar = Calendar.getInstance(UTC_TIMEZONE, Locale.US);
         calendar.clear();
         calendar.set(Calendar.YEAR, year);
         calendar.set(Calendar.MONTH, month);
         calendar.set(Calendar.DAY_OF_MONTH, dayOfMonth);
         return calendar;
     }

     public static boolean isYearSet(Calendar cal) {
         // use the Calendar.YEAR field to track whether or not the year is set instead of
         // Calendar.isSet() because doing Calendar.get() causes Calendar.isSet() to become
         // true irregardless of what the previous value was
         return cal.get(Calendar.YEAR) > 1;
     }

     /**
      * Same as {@link #formatDate(Context context, String string, boolean longForm)}, with
      * longForm set to {@code true} by default.
      *
      * @param context Valid context
      * @param string String representation of a date to parse
      * @return Returns the same date in a cleaned up format. If the supplied string does not look
      * like a date, return it unchanged.
      */

     public static String formatDate(Context context, String string) {
         return formatDate(context, string, true);
     }

     /**
      * Parses the supplied string to see if it looks like a date.
      *
      * @param context Valid context
      * @param string String representation of a date to parse
      * @param longForm If true, return the date formatted into its long string representation.
      * If false, return the date formatted using its short form representation (i.e. 12/11/2012)
      * @return Returns the same date in a cleaned up format. If the supplied string does not look
      * like a date, return it unchanged.
      */
     public static String formatDate(Context context, String string, boolean longForm) {
         if (string == null) {
             return null;
         }

         string = string.trim();
         if (string.length() == 0) {
             return string;
         }
         final Calendar cal = parseDate(string, false);

         // we weren't able to parse the string successfully so just return it unchanged
         if (cal == null) {
             return string;
         }

         final boolean isYearSet = isYearSet(cal);
         final java.text.DateFormat outFormat;
         if (!isYearSet) {
             outFormat = getLocalizedDateFormatWithoutYear(context);
         } else {
             outFormat =
                     longForm ? DateFormat.getLongDateFormat(context) :
                     DateFormat.getDateFormat(context);
         }
         synchronized (outFormat) {
             outFormat.setTimeZone(UTC_TIMEZONE);
             return outFormat.format(cal.getTime());
         }
     }

     public static boolean isMonthBeforeDay(Context context) {
         char[] dateFormatOrder = DateFormat.getDateFormatOrder(context);
         for (int i = 0; i < dateFormatOrder.length; i++) {
             if (dateFormatOrder[i] == DateFormat.DATE) {
                 return false;
             }
             if (dateFormatOrder[i] == DateFormat.MONTH) {
                 return true;
             }
         }
         return false;
     }

     /**
      * Returns a SimpleDateFormat object without the year fields by using a regular expression
      * to eliminate the year in the string pattern. In the rare occurence that the resulting
      * pattern cannot be reconverted into a SimpleDateFormat, it uses the provided context to
      * determine whether the month field should be displayed before the day field, and returns
      * either "MMMM dd" or "dd MMMM" converted into a SimpleDateFormat.
      */
     public static java.text.DateFormat getLocalizedDateFormatWithoutYear(Context context) {
         final String pattern = ((SimpleDateFormat) SimpleDateFormat.getDateInstance(
                 java.text.DateFormat.LONG)).toPattern();
         // Determine the correct regex pattern for year.
         // Special case handling for Spanish locale by checking for "de"
         final String yearPattern = pattern.contains(
                 "de") ? "[^Mm]*[Yy]+[^Mm]*" : "[^DdMm]*[Yy]+[^DdMm]*";
         try {
          // Eliminate the substring in pattern that matches the format for that of year
             return new SimpleDateFormat(pattern.replaceAll(yearPattern, ""));
         } catch (IllegalArgumentException e) {
             return new SimpleDateFormat(
                     DateUtils.isMonthBeforeDay(context) ? "MMMM dd" : "dd MMMM");
         }
     }

     /**
      * Given a calendar (possibly containing only a day of the year), returns the earliest possible
      * anniversary of the date that is equal to or after the current point in time if the date
      * does not contain a year, or the date converted to the local time zone (if the date contains
      * a year.
      *
      * @param target The date we wish to convert(in the UTC time zone).
      * @return If date does not contain a year (year < 1900), returns the next earliest anniversary
      * that is after the current point in time (in the local time zone). Otherwise, returns the
      * adjusted Date in the local time zone.
      */
     public static Date getNextAnnualDate(Calendar target) {
         final Calendar today = Calendar.getInstance();
         today.setTime(new Date());

         // Round the current time to the exact start of today so that when we compare
         // today against the target date, both dates are set to exactly 0000H.
         today.set(Calendar.HOUR_OF_DAY, 0);
         today.set(Calendar.MINUTE, 0);
         today.set(Calendar.SECOND, 0);
         today.set(Calendar.MILLISECOND, 0);

         final boolean isYearSet = isYearSet(target);
         final int targetYear = target.get(Calendar.YEAR);
         final int targetMonth = target.get(Calendar.MONTH);
         final int targetDay = target.get(Calendar.DAY_OF_MONTH);
         final boolean isFeb29 = (targetMonth == Calendar.FEBRUARY && targetDay == 29);
         final GregorianCalendar anniversary = new GregorianCalendar();
         // Convert from the UTC date to the local date. Set the year to today's year if the
         // there is no provided year (targetYear < 1900)
         anniversary.set(!isYearSet ? today.get(Calendar.YEAR) : targetYear,
                 targetMonth, targetDay);
         // If the anniversary's date is before the start of today and there is no year set,
         // increment the year by 1 so that the returned date is always equal to or greater than
         // today. If the day is a leap year, keep going until we get the next leap year anniversary
         // Otherwise if there is already a year set, simply return the exact date.
         if (!isYearSet) {
             int anniversaryYear = today.get(Calendar.YEAR);
             if (anniversary.before(today) ||
                     (isFeb29 && !anniversary.isLeapYear(anniversaryYear))) {
                 // If the target date is not Feb 29, then set the anniversary to the next year.
                 // Otherwise, keep going until we find the next leap year (this is not guaranteed
                 // to be in 4 years time).
                 do {
                     anniversaryYear +=1;
                 } while (isFeb29 && !anniversary.isLeapYear(anniversaryYear));
                 anniversary.set(anniversaryYear, targetMonth, targetDay);
             }
         }
         return anniversary.getTime();
     }
 }
	/*
	* Copyright (C) 2010 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package com.android.contacts.common.util;

	import android.content.Context;
	import android.text.format.DateFormat;


	import java.text.ParsePosition;
	import java.text.SimpleDateFormat;
	import java.util.Calendar;
	import java.util.Date;
	import java.util.GregorianCalendar;
	import java.util.Locale;
	import java.util.TimeZone;

	/**
	* Utility methods for processing dates.
	*/
	public class DateUtils {
	public static final TimeZone UTC_TIMEZONE = TimeZone.getTimeZone("UTC");

	/**
	* When parsing a date without a year, the system assumes 1970, which wasn't a leap-year.
	* Let's add a one-off hack for that day of the year
	*/
	public static final String NO_YEAR_DATE_FEB29TH = "--02-29";

	// Variations of ISO 8601 date format. Do not change the order - it does affect the
	// result in ambiguous cases.
	private static final SimpleDateFormat[] DATE_FORMATS = {
	CommonDateUtils.FULL_DATE_FORMAT,
	CommonDateUtils.DATE_AND_TIME_FORMAT,
	new SimpleDateFormat("yyyy-MM-dd'T'HH:mm'Z'", Locale.US),
	new SimpleDateFormat("yyyyMMdd", Locale.US),
	new SimpleDateFormat("yyyyMMdd'T'HHmmssSSS'Z'", Locale.US),
	new SimpleDateFormat("yyyyMMdd'T'HHmmss'Z'", Locale.US),
	new SimpleDateFormat("yyyyMMdd'T'HHmm'Z'", Locale.US),
	};

	static {
	for (SimpleDateFormat format : DATE_FORMATS) {
	format.setLenient(true);
	format.setTimeZone(UTC_TIMEZONE);
	}
	CommonDateUtils.NO_YEAR_DATE_FORMAT.setTimeZone(UTC_TIMEZONE);
	}

	/**
	* Parses the supplied string to see if it looks like a date.
	*
	* @param string The string representation of the provided date
	* @param mustContainYear If true, the string is parsed as a date containing a year. If false,
	* the string is parsed into a valid date even if the year field is missing.
	* @return A Calendar object corresponding to the date if the string is successfully parsed.
	* If not, null is returned.
	*/
	public static Calendar parseDate(String string, boolean mustContainYear) {
	ParsePosition parsePosition = new ParsePosition(0);
	Date date;
	if (!mustContainYear) {
	final boolean noYearParsed;
	// Unfortunately, we can't parse Feb 29th correctly, so let's handle this day seperately
	if (NO_YEAR_DATE_FEB29TH.equals(string)) {
	return getUtcDate(0, Calendar.FEBRUARY, 29);
	} else {
	synchronized (CommonDateUtils.NO_YEAR_DATE_FORMAT) {
	date = CommonDateUtils.NO_YEAR_DATE_FORMAT.parse(string, parsePosition);
	}
	noYearParsed = parsePosition.getIndex() == string.length();
	}

	if (noYearParsed) {
	return getUtcDate(date, true);
	}
	}
	for (int i = 0; i < DATE_FORMATS.length; i++) {
	SimpleDateFormat f = DATE_FORMATS[i];
	synchronized (f) {
	parsePosition.setIndex(0);
	date = f.parse(string, parsePosition);
	if (parsePosition.getIndex() == string.length()) {
	return getUtcDate(date, false);
	}
	}
	}
	return null;
	}

	private static final Calendar getUtcDate(Date date, boolean noYear) {
	final Calendar calendar = Calendar.getInstance(UTC_TIMEZONE, Locale.US);
	calendar.setTime(date);
	if (noYear) {
	calendar.set(Calendar.YEAR, 0);
	}
	return calendar;
	}

	private static final Calendar getUtcDate(int year, int month, int dayOfMonth) {
	final Calendar calendar = Calendar.getInstance(UTC_TIMEZONE, Locale.US);
	calendar.clear();
	calendar.set(Calendar.YEAR, year);
	calendar.set(Calendar.MONTH, month);
	calendar.set(Calendar.DAY_OF_MONTH, dayOfMonth);
	return calendar;
	}

	public static boolean isYearSet(Calendar cal) {
	// use the Calendar.YEAR field to track whether or not the year is set instead of
	// Calendar.isSet() because doing Calendar.get() causes Calendar.isSet() to become
	// true irregardless of what the previous value was
	return cal.get(Calendar.YEAR) > 1;
	}

	/**
	* Same as {@link #formatDate(Context context, String string, boolean longForm)}, with
	* longForm set to {@code true} by default.
	*
	* @param context Valid context
	* @param string String representation of a date to parse
	* @return Returns the same date in a cleaned up format. If the supplied string does not look
	* like a date, return it unchanged.
	*/

	public static String formatDate(Context context, String string) {
	return formatDate(context, string, true);
	}

	/**
	* Parses the supplied string to see if it looks like a date.
	*
	* @param context Valid context
	* @param string String representation of a date to parse
	* @param longForm If true, return the date formatted into its long string representation.
	* If false, return the date formatted using its short form representation (i.e. 12/11/2012)
	* @return Returns the same date in a cleaned up format. If the supplied string does not look
	* like a date, return it unchanged.
	*/
	public static String formatDate(Context context, String string, boolean longForm) {
	if (string == null) {
	return null;
	}

	string = string.trim();
	if (string.length() == 0) {
	return string;
	}
	final Calendar cal = parseDate(string, false);

	// we weren't able to parse the string successfully so just return it unchanged
	if (cal == null) {
	return string;
	}

	final boolean isYearSet = isYearSet(cal);
	final java.text.DateFormat outFormat;
	if (!isYearSet) {
	outFormat = getLocalizedDateFormatWithoutYear(context);
	} else {
	outFormat =
	longForm ? DateFormat.getLongDateFormat(context) :
	DateFormat.getDateFormat(context);
	}
	synchronized (outFormat) {
	outFormat.setTimeZone(UTC_TIMEZONE);
	return outFormat.format(cal.getTime());
	}
	}

	public static boolean isMonthBeforeDay(Context context) {
	char[] dateFormatOrder = DateFormat.getDateFormatOrder(context);
	for (int i = 0; i < dateFormatOrder.length; i++) {
	if (dateFormatOrder[i] == DateFormat.DATE) {
	return false;
	}
	if (dateFormatOrder[i] == DateFormat.MONTH) {
	return true;
	}
	}
	return false;
	}

	/**
	* Returns a SimpleDateFormat object without the year fields by using a regular expression
	* to eliminate the year in the string pattern. In the rare occurence that the resulting
	* pattern cannot be reconverted into a SimpleDateFormat, it uses the provided context to
	* determine whether the month field should be displayed before the day field, and returns
	* either "MMMM dd" or "dd MMMM" converted into a SimpleDateFormat.
	*/
	public static java.text.DateFormat getLocalizedDateFormatWithoutYear(Context context) {
	final String pattern = ((SimpleDateFormat) SimpleDateFormat.getDateInstance(
	java.text.DateFormat.LONG)).toPattern();
	// Determine the correct regex pattern for year.
	// Special case handling for Spanish locale by checking for "de"
	final String yearPattern = pattern.contains(
	"de") ? "[^Mm][Yy]+[^Mm]" : "[^DdMm][Yy]+[^DdMm]";
	try {
	// Eliminate the substring in pattern that matches the format for that of year
	return new SimpleDateFormat(pattern.replaceAll(yearPattern, ""));
	} catch (IllegalArgumentException e) {
	return new SimpleDateFormat(
	DateUtils.isMonthBeforeDay(context) ? "MMMM dd" : "dd MMMM");
	}
	}

	/**
	* Given a calendar (possibly containing only a day of the year), returns the earliest possible
	* anniversary of the date that is equal to or after the current point in time if the date
	* does not contain a year, or the date converted to the local time zone (if the date contains
	* a year.
	*
	* @param target The date we wish to convert(in the UTC time zone).
	* @return If date does not contain a year (year < 1900), returns the next earliest anniversary
	* that is after the current point in time (in the local time zone). Otherwise, returns the
	* adjusted Date in the local time zone.
	*/
	public static Date getNextAnnualDate(Calendar target) {
	final Calendar today = Calendar.getInstance();
	today.setTime(new Date());

	// Round the current time to the exact start of today so that when we compare
	// today against the target date, both dates are set to exactly 0000H.
	today.set(Calendar.HOUR_OF_DAY, 0);
	today.set(Calendar.MINUTE, 0);
	today.set(Calendar.SECOND, 0);
	today.set(Calendar.MILLISECOND, 0);

	final boolean isYearSet = isYearSet(target);
	final int targetYear = target.get(Calendar.YEAR);
	final int targetMonth = target.get(Calendar.MONTH);
	final int targetDay = target.get(Calendar.DAY_OF_MONTH);
	final boolean isFeb29 = (targetMonth == Calendar.FEBRUARY && targetDay == 29);
	final GregorianCalendar anniversary = new GregorianCalendar();
	// Convert from the UTC date to the local date. Set the year to today's year if the
	// there is no provided year (targetYear < 1900)
	anniversary.set(!isYearSet ? today.get(Calendar.YEAR) : targetYear,
	targetMonth, targetDay);
	// If the anniversary's date is before the start of today and there is no year set,
	// increment the year by 1 so that the returned date is always equal to or greater than
	// today. If the day is a leap year, keep going until we get the next leap year anniversary
	// Otherwise if there is already a year set, simply return the exact date.
	if (!isYearSet) {
	int anniversaryYear = today.get(Calendar.YEAR);
	if (anniversary.before(today) \|\|
	(isFeb29 && !anniversary.isLeapYear(anniversaryYear))) {
	// If the target date is not Feb 29, then set the anniversary to the next year.
	// Otherwise, keep going until we find the next leap year (this is not guaranteed
	// to be in 4 years time).
	do {
	anniversaryYear +=1;
	} while (isFeb29 && !anniversary.isLeapYear(anniversaryYear));
	anniversary.set(anniversaryYear, targetMonth, targetDay);
	}
	}
	return anniversary.getTime();
	}
	}