CalendarImplpublic class CalendarImpl extends Calendar This class is an implementation of the subsetted
CLDC 1.1 Calendar class. |
Fields Summary |
---|
private static final int | BC | private static final int | AD | private static final int | JAN_1_1_JULIAN_DAY | private static final int | EPOCH_JULIAN_DAY | private static final int[] | NUM_DAYS | private static final int[] | LEAP_NUM_DAYS | private static final int | ONE_SECONDUseful millisecond constants. Although ONE_DAY and ONE_WEEK can fit
into ints, they must be longs in order to prevent arithmetic overflow
when performing (CR 4173516). | private static final int | ONE_MINUTE | private static final int | ONE_HOUR | private static final long | ONE_DAY | private static final long | gregorianCutoverThe point at which the Gregorian calendar rules are used, measured in
milliseconds from the standard epoch. Default is October 15, 1582
(Gregorian) 00:00:00 UTC or -12219292800000L. For this value, October 4,
1582 (Julian) is followed by October 15, 1582 (Gregorian). This
corresponds to Julian day number 2299161. | private static final int | gregorianCutoverYearThe year of the gregorianCutover, with 0 representing
1 BC, -1 representing 2 BC, etc. | static String[] | months | static String[] | days |
Constructors Summary |
---|
public CalendarImpl()
super();
|
Methods Summary |
---|
private static final java.lang.StringBuffer | appendFourDigits(java.lang.StringBuffer sb, int number)
if (number >= 0 && number < 1000) {
sb.append('0");
if (number < 100) {
sb.append('0");
}
if (number < 10) {
sb.append('0");
}
}
return sb.append(number);
| private static final java.lang.StringBuffer | appendTwoDigits(java.lang.StringBuffer sb, int number)
if (number < 10) {
sb.append('0");
}
return sb.append(number);
| private final long | calculateJulianDay(boolean isGregorian, int year)Compute the Julian day number under either the Gregorian or the
Julian calendar, using the given year and the remaining fields.
int month = 0;
long millis = 0;
month = this.fields[MONTH] - JANUARY;
// If the month is out of range, adjust it into range
if (month < 0 || month > 11) {
int[] rem = new int[1];
year += floorDivide(month, 12, rem);
month = rem[0];
}
boolean isLeap = year%4 == 0;
long julianDay =
365L*(year - 1) + floorDivide((year - 1), 4) + (JAN_1_1_JULIAN_DAY - 3);
if (isGregorian) {
isLeap = isLeap && ((year%100 != 0) || (year%400 == 0));
// Add 2 because Gregorian calendar starts 2 days after Julian calendar
julianDay +=
floorDivide((year - 1), 400) - floorDivide((year - 1), 100) + 2;
}
// At this point julianDay is the 0-based day BEFORE the first day of
// January 1, year 1 of the given calendar. If julianDay == 0, it
// specifies (Jan. 1, 1) - 1, in whatever calendar we are using (Julian
// or Gregorian).
julianDay += isLeap ? LEAP_NUM_DAYS[month] : NUM_DAYS[month];
julianDay += this.fields[DATE];
return julianDay;
| protected void | computeFields()Converts UTC as milliseconds to time field values.
int rawOffset = getTimeZone().getRawOffset();
long localMillis = time + rawOffset;
// Check for very extreme values -- millis near Long.MIN_VALUE or
// Long.MAX_VALUE. For these values, adding the zone offset can push
// the millis past MAX_VALUE to MIN_VALUE, or vice versa. This produces
// the undesirable effect that the time can wrap around at the ends,
// yielding, for example, a Date(Long.MAX_VALUE) with a big BC year
// (should be AD). Handle this by pinning such values to Long.MIN_VALUE
// or Long.MAX_VALUE. - liu 8/11/98 CR 4149677
if (time > 0 && localMillis < 0 && rawOffset > 0) {
localMillis = Long.MAX_VALUE;
} else if (time < 0 && localMillis > 0 && rawOffset < 0) {
localMillis = Long.MIN_VALUE;
}
// Time to fields takes the wall millis (Standard or DST).
timeToFields(localMillis);
long days = (long)(localMillis / ONE_DAY);
int millisInDay = (int)(localMillis - (days * ONE_DAY));
if (millisInDay < 0) millisInDay += ONE_DAY;
// Call getOffset() to get the TimeZone offset.
// The millisInDay value must be standard local millis.
int dstOffset = getTimeZone().getOffset(AD,
this.fields[YEAR],
this.fields[MONTH],
this.fields[DATE],
this.fields[DAY_OF_WEEK],
millisInDay) - rawOffset;
// Adjust our millisInDay for DST, if necessary.
millisInDay += dstOffset;
// If DST has pushed us into the next day,
// we must call timeToFields() again.
// This happens in DST between 12:00 am and 1:00 am every day.
// The call to timeToFields() will give the wrong day,
// since the Standard time is in the previous day
if (millisInDay >= ONE_DAY) {
long dstMillis = localMillis + dstOffset;
millisInDay -= ONE_DAY;
// As above, check for and pin extreme values
if (localMillis > 0 && dstMillis < 0 && dstOffset > 0) {
dstMillis = Long.MAX_VALUE;
} else if (localMillis < 0 && dstMillis > 0 && dstOffset < 0) {
dstMillis = Long.MIN_VALUE;
}
timeToFields(dstMillis);
}
// Fill in all time-related fields based on millisInDay.
// so as not to perturb flags.
this.fields[MILLISECOND] = millisInDay % 1000;
millisInDay /= 1000;
this.fields[SECOND] = millisInDay % 60;
millisInDay /= 60;
this.fields[MINUTE] = millisInDay % 60;
millisInDay /= 60;
this.fields[HOUR_OF_DAY] = millisInDay;
this.fields[AM_PM] = millisInDay / 12;
this.fields[HOUR] = millisInDay % 12;
| protected void | computeTime()Converts time field values to UTC as milliseconds.
correctTime();
// This function takes advantage of the fact that unset fields in
// the time field list have a value of zero.
// First, use the year to determine whether to use the Gregorian or the
// Julian calendar. If the year is not the year of the cutover, this
// computation will be correct. But if the year is the cutover year,
// this may be incorrect. In that case, assume the Gregorian calendar,
// make the computation, and then recompute if the resultant millis
// indicate the wrong calendar has been assumed.
// A date such as Oct. 10, 1582 does not exist in a Gregorian calendar
// with the default changeover of Oct. 15, 1582, since in such a
// calendar Oct. 4 (Julian) is followed by Oct. 15 (Gregorian). This
// algorithm will interpret such a date using the Julian calendar,
// yielding Oct. 20, 1582 (Gregorian).
int year = this.fields[YEAR];
boolean isGregorian = year >= gregorianCutoverYear;
long julianDay = calculateJulianDay(isGregorian, year);
long millis = julianDayToMillis(julianDay);
// The following check handles portions of the cutover year BEFORE the
// cutover itself happens. The check for the julianDate number is for a
// rare case; it's a hardcoded number, but it's efficient. The given
// Julian day number corresponds to Dec 3, 292269055 BC, which
// corresponds to millis near Long.MIN_VALUE. The need for the check
// arises because for extremely negative Julian day numbers, the millis
// actually overflow to be positive values. Without the check, the
// initial date is interpreted with the Gregorian calendar, even when
// the cutover doesn't warrant it.
if (isGregorian != (millis >= gregorianCutover) &&
julianDay != -106749550580L) { // See above
julianDay = calculateJulianDay(!isGregorian, year);
millis = julianDayToMillis(julianDay);
}
// Do the time portion of the conversion.
int millisInDay = 0;
// Hours
// Don't normalize here; let overflow bump into the next period.
// This is consistent with how we handle other fields.
millisInDay += this.fields[HOUR_OF_DAY];
millisInDay *= 60;
// now get minutes
millisInDay += this.fields[MINUTE];
millisInDay *= 60;
// now get seconds
millisInDay += this.fields[SECOND];
millisInDay *= 1000;
// now get millis
millisInDay += this.fields[MILLISECOND];
// Compute the time zone offset and DST offset. There are two potential
// ambiguities here. We'll assume a 2:00 am (wall time) switchover time
// for discussion purposes here.
// 1. The transition into DST. Here, a designated time of 2:00 am - 2:59 am
// can be in standard or in DST depending. However, 2:00 am is an invalid
// representation (the representation jumps from 1:59:59 am Std to 3:00:00 am DST).
// We assume standard time.
// 2. The transition out of DST. Here, a designated time of 1:00 am - 1:59 am
// can be in standard or DST. Both are valid representations (the rep
// jumps from 1:59:59 DST to 1:00:00 Std).
// Again, we assume standard time.
// We use the TimeZone object to get the zone offset
int zoneOffset = getTimeZone().getRawOffset();
// Now add date and millisInDay together, to make millis contain local wall
// millis, with no zone or DST adjustments
millis += millisInDay;
// Normalize the millisInDay to 0..ONE_DAY-1. If the millis is out
// of range, then we must call timeToFields() to recompute our
// fields.
int[] normalizedMillisInDay = new int[1];
floorDivide(millis, (int)ONE_DAY, normalizedMillisInDay);
// We need to have the month, the day, and the day of the week.
// Calling timeToFields will compute the MONTH and DATE fields.
//
// It's tempting to try to use DAY_OF_WEEK here, if it
// is set, but we CAN'T. Even if it's set, it might have
// been set wrong by the user. We should rely only on
// the Julian day number, which has been computed correctly
// using the disambiguation algorithm above. [LIU]
int dow = julianDayToDayOfWeek(julianDay);
// It's tempting to try to use DAY_OF_WEEK here, if it
// is set, but we CAN'T. Even if it's set, it might have
// been set wrong by the user. We should rely only on
// the Julian day number, which has been computed correctly
// using the disambiguation algorithm above. [LIU]
int dstOffset = getTimeZone().getOffset(AD,
this.fields[YEAR],
this.fields[MONTH],
this.fields[DATE],
dow,
normalizedMillisInDay[0]) -
zoneOffset;
// Note: Because we pass in wall millisInDay, rather than
// standard millisInDay, we interpret "1:00 am" on the day
// of cessation of DST as "1:00 am Std" (assuming the time
// of cessation is 2:00 am).
// Store our final computed GMT time, with timezone adjustments.
time = millis - zoneOffset - dstOffset;
| private void | correctTime()Validates the field values for HOUR_OF_DAY, AM_PM and HOUR
The calendar will give preference in the following order
HOUR_OF_DAY, AM_PM, HOUR
int value;
if (isSet[HOUR_OF_DAY]) {
value = this.fields[HOUR_OF_DAY] % 24;
this.fields[HOUR_OF_DAY] = value;
this.fields[AM_PM] = (value < 12) ? AM : PM;
this.isSet[HOUR_OF_DAY] = false;
return;
}
if(isSet[AM_PM]) {
// Determines AM PM with the 24 hour clock
// This prevents the user from inputing an invalid one.
if (this.fields[AM_PM] != AM && this.fields[AM_PM] != PM) {
value = this.fields[HOUR_OF_DAY];
this.fields[AM_PM] = (value < 12) ? AM : PM;
}
this.isSet[AM_PM] = false;
}
if (isSet[HOUR]) {
value = this.fields[HOUR];
if (value > 12) {
this.fields[HOUR_OF_DAY] = (value % 12) + 12;
this.fields[HOUR] = value % 12;
this.fields[AM_PM] = PM;
} else {
if (this.fields[AM_PM] == PM) {
this.fields[HOUR_OF_DAY] = value + 12;
} else {
this.fields[HOUR_OF_DAY] = value;
}
}
this.isSet[HOUR] = false;
}
| private static final long | floorDivide(long numerator, long denominator)Divide two long integers, returning the floor of the quotient.
Unlike the built-in division, this is mathematically well-behaved.
E.g., -1/4 => 0
but floorDivide(-1,4) => -1.
// We do this computation in order to handle
// a numerator of Long.MIN_VALUE correctly
return (numerator >= 0) ?
numerator / denominator :
((numerator + 1) / denominator) - 1;
| private static final int | floorDivide(int numerator, int denominator)Divide two integers, returning the floor of the quotient.
Unlike the built-in division, this is mathematically well-behaved.
E.g., -1/4 => 0
but floorDivide(-1,4) => -1.
// We do this computation in order to handle
// a numerator of Integer.MIN_VALUE correctly
return (numerator >= 0) ?
numerator / denominator :
((numerator + 1) / denominator) - 1;
| private static final int | floorDivide(int numerator, int denominator, int[] remainder)Divide two integers, returning the floor of the quotient, and
the modulus remainder.
Unlike the built-in division, this is mathematically well-behaved.
E.g., -1/4 => 0 and -1%4 => -1,
but floorDivide(-1,4) => -1 with remainder[0] => 3.
if (numerator >= 0) {
remainder[0] = numerator % denominator;
return numerator / denominator;
}
int quotient = ((numerator + 1) / denominator) - 1;
remainder[0] = numerator - (quotient * denominator);
return quotient;
| private static final int | floorDivide(long numerator, int denominator, int[] remainder)Divide two integers, returning the floor of the quotient, and
the modulus remainder.
Unlike the built-in division, this is mathematically well-behaved.
E.g., -1/4 => 0 and -1%4 => -1,
but floorDivide(-1,4) => -1 with remainder[0] => 3.
if (numerator >= 0) {
remainder[0] = (int)(numerator % denominator);
return (int)(numerator / denominator);
}
int quotient = (int)(((numerator + 1) / denominator) - 1);
remainder[0] = (int)(numerator - (quotient * denominator));
return quotient;
| private static final int | julianDayToDayOfWeek(long julian)
// If julian is negative, then julian%7 will be negative, so we adjust
// accordingly. We add 1 because Julian day 0 is Monday.
int dayOfWeek = (int)((julian + 1) % 7);
return dayOfWeek + ((dayOfWeek < 0) ? (7 + SUNDAY) : SUNDAY);
| private static final long | julianDayToMillis(long julian)Converts Julian day to time as milliseconds.
return (julian - EPOCH_JULIAN_DAY) * ONE_DAY;
| private static final long | millisToJulianDay(long millis)Converts time as milliseconds to Julian day.
return EPOCH_JULIAN_DAY + floorDivide(millis, ONE_DAY);
| private final void | timeToFields(long theTime)Convert the time as milliseconds to the date fields. Millis must be
given as local wall millis to get the correct local day. For example,
if it is 11:30 pm Standard, and DST is in effect, the correct DST millis
must be passed in to get the right date.
Fields that are completed by this method: YEAR, MONTH, DATE, DAY_OF_WEEK.
int dayOfYear, weekCount, rawYear;
boolean isLeap;
// Compute the year, month, and day of month from the given millis
if (theTime >= gregorianCutover) {
// The Gregorian epoch day is zero for Monday January 1, year 1.
long gregorianEpochDay =
millisToJulianDay(theTime) - JAN_1_1_JULIAN_DAY;
// Here we convert from the day number to the multiple radix
// representation. We use 400-year, 100-year, and 4-year cycles.
// For example, the 4-year cycle has 4 years + 1 leap day; giving
// 1461 == 365*4 + 1 days.
int[] rem = new int[1];
// 400-year cycle length
int n400 = floorDivide(gregorianEpochDay, 146097, rem);
// 100-year cycle length
int n100 = floorDivide(rem[0], 36524, rem);
// 4-year cycle length
int n4 = floorDivide(rem[0], 1461, rem);
int n1 = floorDivide(rem[0], 365, rem);
rawYear = 400*n400 + 100*n100 + 4*n4 + n1;
// zero-based day of year
dayOfYear = rem[0];
// Dec 31 at end of 4- or 400-yr cycle
if (n100 == 4 || n1 == 4) {
dayOfYear = 365;
} else {
++rawYear;
}
// equiv. to (rawYear%4 == 0)
isLeap =
((rawYear&0x3) == 0) && (rawYear%100 != 0 || rawYear%400 == 0);
// Gregorian day zero is a Monday
this.fields[DAY_OF_WEEK] = (int)((gregorianEpochDay+1) % 7);
} else {
// The Julian epoch day (not the same as Julian Day)
// is zero on Saturday December 30, 0 (Gregorian).
long julianEpochDay =
millisToJulianDay(theTime) - (JAN_1_1_JULIAN_DAY - 2);
rawYear = (int) floorDivide(4*julianEpochDay + 1464, 1461);
// Compute the Julian calendar day number for January 1, year
long january1 = 365*(rawYear-1) + floorDivide(rawYear-1, 4);
dayOfYear = (int)(julianEpochDay - january1); // 0-based
// Julian leap years occurred historically every 4 years starting
// with 8 AD. Before 8 AD the spacing is irregular; every 3 years
// from 45 BC to 9 BC, and then none until 8 AD. However, we don't
// implement this historical detail; instead, we implement the
// computationally cleaner proleptic calendar, which assumes
// consistent 4-year cycles throughout time.
// equiv. to (rawYear%4 == 0)
isLeap = ((rawYear&0x3) == 0);
// Julian calendar day zero is a Saturday
this.fields[DAY_OF_WEEK] = (int)((julianEpochDay-1) % 7);
}
// Common Julian/Gregorian calculation
int correction = 0;
// zero-based DOY for March 1
int march1 = isLeap ? 60 : 59;
if (dayOfYear >= march1) correction = isLeap ? 1 : 2;
// zero-based month
int month_field = (12 * (dayOfYear + correction) + 6) / 367;
// one-based DOM
int date_field = dayOfYear -
(isLeap ? LEAP_NUM_DAYS[month_field] : NUM_DAYS[month_field]) + 1;
// Normalize day of week
this.fields[DAY_OF_WEEK] += (this.fields[DAY_OF_WEEK] < 0) ? (SUNDAY+7) : SUNDAY;
this.fields[YEAR] = rawYear;
// If year is < 1 we are in BC
if (this.fields[YEAR] < 1) {
this.fields[YEAR] = 1 - this.fields[YEAR];
}
// 0-based
this.fields[MONTH] = month_field + JANUARY;
this.fields[DATE] = date_field;
| public static java.lang.String | toISO8601String(java.util.Calendar calendar)Converts this Date object to a String .
The output format is as follows:
yyyy MM dd hh mm ss +zzzz
where:
- yyyy
is the year, as four decimal digits.
Year values larger than - 9999
will be truncated
to - 9999
.
- MM
is the month (- 01
through - 12
),
as two decimal digits.
- dd
is the day of the month (- 01
through
- 31
), as two decimal digits.
- hh
is the hour of the day (- 00
through
- 23
), as two decimal digits.
- mm
is the minute within the hour (- 00
through - 59
), as two decimal digits.
- ss
is the second within the minute (- 00
through - 59
), as two decimal digits.
- zzzz
is the time zone offset in hours and minutes
(four decimal digits - "hhmm"
) relative to GMT,
preceded by a "+" or "-" character (- -1200
through - +1200
).
For instance, Pacific Standard Time zone is printed
as - -0800
. GMT is printed as - +0000
.
// Printing in the absence of a Calendar
// implementation class is not supported
if (calendar == null) {
return "0000 00 00 00 00 00 +0000";
}
int year = calendar.get(Calendar.YEAR);
int month = calendar.get(Calendar.MONTH) + 1;
int day = calendar.get(Calendar.DAY_OF_MONTH);
int hour_of_day = calendar.get(Calendar.HOUR_OF_DAY);
int hour = calendar.get(Calendar.HOUR);
int minute = calendar.get(Calendar.MINUTE);
int seconds = calendar.get(Calendar.SECOND);
String yr = Integer.toString(year);
// The total size of the string buffer
// yr.length+1+2+1+2+1+2+1+2+1+2+1+5 = 25 + yr.length
StringBuffer sb = new StringBuffer(25 + yr.length());
appendFourDigits(sb, year).append(' ");
appendTwoDigits(sb, month).append(' ");
appendTwoDigits(sb, day).append(' ");
appendTwoDigits(sb, hour_of_day).append(' ");
appendTwoDigits(sb, minute).append(' ");
appendTwoDigits(sb, seconds).append(' ");
// TimeZone offset is represented in milliseconds.
// Convert the offset to minutes:
TimeZone t = calendar.getTimeZone();
int zoneOffsetInMinutes = t.getRawOffset() / 1000 / 60;
if (zoneOffsetInMinutes < 0) {
zoneOffsetInMinutes = Math.abs(zoneOffsetInMinutes);
sb.append('-");
} else {
sb.append('+");
}
int zoneHours = zoneOffsetInMinutes / 60;
int zoneMinutes = zoneOffsetInMinutes % 60;
appendTwoDigits(sb, zoneHours);
appendTwoDigits(sb, zoneMinutes);
return sb.toString();
| public static java.lang.String | toString(java.util.Calendar calendar)Converts this Date object to a String
of the form:
dow mon dd hh:mm:ss zzz yyyy
where:
- dow is the day of the week (Sun, Mon, Tue, Wed,
Thu, Fri, Sat).
- mon is the month (Jan, Feb, Mar, Apr, May, Jun,
Jul, Aug, Sep, Oct, Nov, Dec).
- dd is the day of the month (01 through
31), as two decimal digits.
- hh is the hour of the day (00 through
23), as two decimal digits.
- mm is the minute within the hour (00 through
59), as two decimal digits.
- ss is the second within the minute (00 through
61, as two decimal digits.
- zzz is the time zone (and may reflect daylight savings
time). If time zone information is not available,
then zzz is empty - that is, it consists
of no characters at all.
- yyyy is the year, as four decimal digits.
// Printing in the absence of a Calendar
// implementation class is not supported
if (calendar == null) {
return "Thu Jan 01 00:00:00 UTC 1970";
}
int dow = calendar.get(Calendar.DAY_OF_WEEK);
int month = calendar.get(Calendar.MONTH);
int day = calendar.get(Calendar.DAY_OF_MONTH);
int hour_of_day = calendar.get(Calendar.HOUR_OF_DAY);
int minute = calendar.get(Calendar.MINUTE);
int seconds = calendar.get(Calendar.SECOND);
int year = calendar.get(Calendar.YEAR);
String yr = Integer.toString(year);
TimeZone zone = calendar.getTimeZone();
String zoneID = zone.getID();
if (zoneID == null) zoneID = "";
// The total size of the string buffer
// 3+1+3+1+2+1+2+1+2+1+2+1+zoneID.length+1+yr.length
// = 21 + zoneID.length + yr.length
StringBuffer sb = new StringBuffer(25 + zoneID.length() + yr.length());
sb.append(days[dow-1]).append(' ");
sb.append(months[month]).append(' ");
appendTwoDigits(sb, day).append(' ");
appendTwoDigits(sb, hour_of_day).append(':");
appendTwoDigits(sb, minute).append(':");
appendTwoDigits(sb, seconds).append(' ");
if (zoneID.length() > 0) sb.append(zoneID).append(' ");
appendFourDigits(sb, year);
return sb.toString();
|
|