Re: How to convert a Date to int
On 6 May 2006 00:23:48 +0200, "Bjorn Abelli"
<bjorn_abelli@DoNotSpam.hotmail.com> wrote, quoted or indirectly
quoted someone who said :
I haven't looked into detail in your BigDate class, but does that mean that
it doesn't rely on the java.util.Date or Calendar in any way?
Correct. BigDate uses a 32-bit days since 1970 Jan 1 internally
rather than milliseconds. It simplifies calculations that don't
involve time or timezones.
You can convert Dates to BigDates and vice versa.
It was primarily written to fix the bugs and shortcomings of Date.
Date is now almost entirely deprecated.
Calendar has a clumsy UI where you feed it magic numbers to describe
what you want it to do rather than calling methods for each function.
It is an exercise in how to destroy type safety.
Here are some examples of BigDate use and the sort of problem it
tackles easily:
sep();
{
// what is today's date in American format
System.out
.println( "Today American style is " +
BigDate.localToday()
.toDowMMDDYY() );
}
sep();
{
// what is today's date in iso format
System.out
.println( "Today ISO style is " + BigDate.localToday()
.toString() );
}
sep();
{
// What date is it in Greenwich?
BigDate d = BigDate.UTCToday();
System.out
.println( "Today in Greenwich England = "
+ d.toString()
+ "." );
/* 0=Sunday to 6=Saturday */
int dayOfWeek = d.getDayOfWeek();
String[] daysOfTheWeek =
{"Sunday",
"Monday",
"Tuesday",
"Wednesday",
"Thursday",
"Friday",
"Saturday"};
String dayName = daysOfTheWeek[ dayOfWeek ];
System.out.println( "In Greenwich it is " + dayName + "." );
}
sep();
{
// What day of the week is today?
// display ISO 8601:1988 international standard format:
yyyy-mm-dd.
BigDate d = BigDate.localToday();
System.out.println( "Today = " + d.toString() + "." );
/* 0=Sunday to 6=Saturday */
int dayOfWeek = d.getDayOfWeek();
String[] daysOfTheWeek =
{"Sunday",
"Monday",
"Tuesday",
"Wednesday",
"Thursday",
"Friday",
"Saturday"};
String dayName = daysOfTheWeek[ dayOfWeek ];
System.out.println( "Today is " + dayName + "." );
System.out
.println( "Today is dayOfWeek number "
+ d.getDayOfWeek()
+ " if Sunday=0." );
System.out
.println( "Today is dayOfWeek number "
+ d.getCalendarDayOfWeek()
+ " if Sunday=1." );
}
pause();
{
// what season is it?
String[] seasons = new String[] {"spring", "summer", "fall",
"winter"};
System.out
.println( "It is " + seasons[ BigDate.localToday()
.getSeason() ] );
System.out.println( "Season for months are: " );
for ( int i = 1; i <= 12; i++ )
{
BigDate b = new BigDate( 2004, i, 1 );
System.out.println( i + " " + seasons[ b.getSeason() ] );
}
}
pause();
{
// What Date is Cobol yyddd date 99360?
BigDate d = new BigDate( 99 + 1900, 1, 360, BigDate.NORMALISE
);
System.out
.println( "COBOL-style yyddd date 99360 = "
+ d.toString()
+ "." );
}
sep();
{
// How do you convert Java timestamps into Windows timestamps.
// Java timestamps use 64-bit milliseconds since 1970 GMT.
// Windows timestamps use 64-bit value representing the number
// of 100-nanosecond intervals since January 1, 1601.
int windowsBase = BigDate.toOrdinal( 1601, 1, 1 );
int javaBase = BigDate.toOrdinal( 1970, 1, 1 );
int daysDifference = javaBase - windowsBase;
// but Microsoft forgot that
// 86,400,000 = 1000 * 60 * 60 * 24 = milliseconds per day
long millisDifference = daysDifference * 86400000L;
System.out
.println( "To convert Java Timestamps to Windows
Timestamps:" );
System.out
.println( "windows = ( java + "
+ millisDifference
+ "L ) * 10000" );
}
sep();
{
// Display a BigDate with SimpleDateFormat using local time
BigDate bigDate = new BigDate( 1999, 12, 31 );
Date date = bigDate.getLocalDate();
SimpleDateFormat sdf =
new SimpleDateFormat(
"EEEE yyyy/MM/dd G hh:mm:ss aa zz : zzzzzz" );
sdf.setTimeZone( TimeZone.getDefault() ); // local time
String dateString = sdf.format( date );
System.out.println( "Local SimpleDateFormat: " + dateString );
}
sep();
{
// Display a BigDate with SimpleDateFormat using UTC
(Greenwich GMT)
// time
BigDate bigDate = new BigDate( 1999, 12, 31 );
Date date = bigDate.getUTCDate();
SimpleDateFormat sdf =
new SimpleDateFormat(
"EEEE yyyy/MM/dd G hh:mm:ss aa zz : zzzzzz" );
sdf.setTimeZone( TimeZone.getTimeZone( "GMT" ) ); // GMT time
String dateString = sdf.format( date );
System.out.println( "UTC/GMT SimpleDateFormat: " + dateString
);
}
sep();
{
// Display a BigDate with default-locale DateFormat using UTC
// (Greenwich GMT) time
BigDate bigDate = new BigDate( 1999, 12, 31 );
Date date = bigDate.getUTCDate();
DateFormat df = DateFormat.getDateInstance();
df.setTimeZone( TimeZone.getTimeZone( "GMT" ) ); // GMT time
String dateString = df.format( date );
System.out.println( "UTC/GMT locale DateFormat: " + dateString
);
}
sep();
{
// What are the earliest and latest dates BigDate can handle
BigDate d = new BigDate( BigDate.MIN_ORDINAL );
System.out.println( "Earliest BigDate possible is " +
d.toString() );
d.setOrdinal( BigDate.MAX_ORDINAL );
System.out.println( "Latest BigDate possible is " +
d.toString() );
}
sep();
{
// What is the last day of February in 2000, preferred method
BigDate d = new BigDate( 2000, 3, 1 ); /* 2000, March 1 */
d.addDays( -1 ); /* last day of Feb */
System.out.println( "Last day in Feb 2000 = " + d.toString() +
"." );
}
sep();
{
// What is the last day of February in 2004, alternate less
safe,
// no-check method
BigDate d = new BigDate( 2004, 2 + 1, 1 - 1, BigDate.NORMALIZE
); /*
* 2004,
* March
* 0
*/
System.out.println( "Last day in Feb 2004 = " + d.toString() +
"." );
}
sep();
{
// What is the last day of February in 2006, generic method.
BigDate d = new BigDate( 2006, 2, 1 ); /* 2004, Feb 1 */
d.addDays( BigDate.daysInMonth( 2, 2006 ) - 1 );
System.out.println( "Last day in Feb 2006 = " + d.toString() +
"." );
}
sep();
{
// What Date was it yesterday?
BigDate d = BigDate.localToday();
d.addDays( -1 );
System.out.println( "Yesterday = " + d.toString() + "." );
}
sep();
{
// What Date will it be tomorrow?
BigDate d = BigDate.localToday();
d.addDays( 1 );
System.out.println( "Tomorrow = " + d.toString() + "." );
}
sep();
{
// What Date will it be 1000 days from now?
BigDate d = BigDate.localToday();
d.addDays( 1000 );
System.out.println( "Today+1000 days = " + d.toString() + "."
);
}
sep();
{
// What date will it be 50 months after 1998-01-03
// You can think of this as how to turn a possibly invalid
date into
// the equivalent valid one.
BigDate d = new BigDate( 1998, 1 + 50, 3, BigDate.NORMALISE );
System.out.println( "1998-01-03+50 months = " + d.toString() +
"." );
}
sep();
{
// What date will it be 60 months from today
BigDate today = BigDate.localToday();
BigDate d = new BigDate( today.getYYYY(), today.getMM() + 60,
today
.getDD(), BigDate.NORMALISE );
System.out
.println( "60 months from today will be "
+ d.toString()
+ "." );
}
sep();
{
// Was 1830-02-29 a valid date?
boolean ok = BigDate.isValid( 1830, 2, 29 );
System.out
.println( "True or false: 1830/02/29 was a valid date:
"
+ ok
+ "." );
}
sep();
{
// how many seconds between Jan 1, 1900 0:00 and Jan 1, 1970
0:00
// i.e. difference between SNTP and Java timestamp bases.
// No leap seconds to worry about.
long diffInDays =
BigDate.toOrdinal( 1970, 1, 1 ) - BigDate.toOrdinal(
1900,
1,
1
);
long diffInSecs = diffInDays * ( 24 * 60 * 60L );
System.out
.println( diffInDays
+ " days or "
+ diffInSecs
+ " seconds between 1900 Jan 1 and 1970 Jan
1" );
}
sep();
{
// How Many days since 1970 is today ?
BigDate d = BigDate.localToday();
System.out.println( "Today is " + d.getOrdinal() + " days
since 1970" );
}
sep();
{
// How Many days since 1970 is 2000/2/29?
BigDate d = new BigDate( 2000, 2, 29 );
System.out
.println( "1999-12-29 is "
+ d.getOrdinal()
+ " days since 1970" );
}
sep();
{
// How Many milliseconds since 1970 is 1999/11/7
BigDate d = new BigDate( 1999, 11, 7 );
System.out
.println( "1999-11-7 is "
+ d.getLocalTimeStamp()
+ " milliseconds since 1970" );
}
sep();
{
// Is the year 2000 a leap year?
System.out
.println( "True or false: 2000 is a leap year: "
+ BigDate.isLeap( 2000 )
+ "." );
}
sep();
{
// What is the last day of this week, e.g. this Saturday?
// display yyyy/mm/dd format.
BigDate d = BigDate.localToday();
/* 0=Sunday to 6=Saturday */
d.addDays( 6 - d.getDayOfWeek() );
System.out.println( "This Saturday is " + d.toString() + "."
);
}
sep();
{
// In what week number did 1999/08/20 fall?
BigDate d = new BigDate( 1999, 8, 20 );
System.out
.println( "1999/08/20 fell in ISO week number "
+ d.getISOWeekNumber()
+ " on ISO day of week number "
+ d.getISODayOfWeek()
+ "." );
System.out
.println(
" According to BigDate.getWeekNumber that is
week number "
+ d.getWeekNumber() );
GregorianCalendar g = new GregorianCalendar( 1999, 8 - 1, 20
);
System.out
.println(
" According to java.util.Calendar that is week
number "
+ g.get( Calendar.WEEK_OF_YEAR )
+ "." );
}
sep();
{
// what is the next business day?
BigDate d = BigDate.localToday();
int interval;
switch ( d.getDayOfWeek() )
{
case 5 /* Friday -> Monday */:
interval = 3;
break;
case 6 /* Saturday -> Monday */:
interval = 2;
break;
case 0 /* Sunday -> Monday */:
case 1 /* Monday -> Tuesday */:
case 2 /* Tuesday -> Wednesday */:
case 3 /* Wednesday -> Thursday */:
case 4 /* Thursday -> Friday */:
default :
interval = 1;
break;
} // end switch
d.addDays( interval );
System.out.println( "Next business day = " + d.toString() +
"." );
}
sep();
{
// What Day of the Month Is The Second Thursday Of This Month?
// This is when the Vancouver PC User Society (VPCUS) meets.
// MacMillan planetarium.
BigDate today = BigDate.localToday();
int dayOfMonthOfSecondThursday = BigDate.nthXXXDay( 2
/* second
*/,
4
/*
thursday */,
today.getYYYY(),
today
.getMM() );
System.out
.println(
"VPCUS meets the second Thursday of the month.
This month's meeting is on the "
+ dayOfMonthOfSecondThursday
+ "th." );
}
sep();
{
// What Day of the Month Is The third Thursday Of This Month?
// This is when the Vancouver Apple User Society meets.
// Scottish Cultural Center, 8886 Hudson, near the Oak St
Bridge
BigDate today = BigDate.localToday();
int dayOfMonthOfThirdThursday = BigDate.nthXXXDay( 3
/* third
*/,
4
/* thursday
*/,
today.getYYYY(),
today.getMM() );
System.out
.println(
"Apples BC meets the third Thursday of the
month. This month's meeting is on the "
+ dayOfMonthOfThirdThursday
+ "th." );
}
sep();
{
// When is the next issue of Xtra West magazine due out
// It came out 2000 July 27, and comes out every two weeks.
BigDate today = BigDate.localToday();
BigDate first = new BigDate( 2000, 7, 27 );
int days = today.getOrdinal() - first.getOrdinal();
int fortnights = ( days + 13 ) / 14; // round up
BigDate next = new BigDate( first.getOrdinal() + fortnights *
14 );
System.out
.println( "Next issue of Xtra West magazine is due out
"
+ next.toString()
+ "." );
}
sep();
{
// When is J. McRee (Mac) Elrod's next potluck?
// http://www.islandnet.com/~jelrod/gpl.html
// the fourth Saturday of the month, jan, apr, jul, oct, every
3
// months.
BigDate today = BigDate.localToday();
int year = today.getYYYY();
// 1>1 2>4 3>4 4>4 5>7 6>7 7>7 8>10 9>10 10>10 11>1 12>1
int month = ( ( ( today.getMM() + ( 3 - 1 - 1 ) ) / 3 ) * 3 )
% 12 + 1;
BigDate when = new BigDate( BigDate.ordinalOfnthXXXDay( 4
/*
fourth */,
6
/*
saturday */,
year,
month
) );
if ( when.getOrdinal() < today.getOrdinal() )
{
// we missed this month's potlock, get next one.
month += 3;
if ( month > 12 )
{
year++;
month -= 12;
when = new BigDate( BigDate.ordinalOfnthXXXDay( 4
/*
fourth */,
6
/*
saturday */,
year,
month
) );
}
}
System.out
.println(
"Mac's next potluck in on the fourth Saturday
of the month, every 3 months,\nNext is on "
+ when );
}
sep();
{
// What Day of the Month Is The Last Friday Of This Month?
BigDate today = BigDate.localToday();
int dayOfMonthOfLastFriday = BigDate.nthXXXDay( 5
/* last */,
5
/* friday */,
today.getYYYY(),
today.getMM()
);
System.out
.println( "The last Friday of the month is on the "
+ dayOfMonthOfLastFriday
+ "th." );
}
sep();
{
// Precisely how old is Roedy Green, in years, months and days
// Roedy was born on February 4, 1948.
BigDate birthDate = new BigDate( 1948, 2, 4 );
BigDate today = BigDate.localToday();
int[] age = BigDate.age( birthDate, today );
System.out
.println( "Today Roedy is "
+ age[ 0 ]
+ " years and "
+ age[ 1 ]
+ " months and "
+ age[ 2 ]
+ " days old." );
System.out
.println( "or "
+ ( today.getOrdinal() -
birthDate.getOrdinal() )
+ " days." );
}
sep();
{
// How old would John Lennon be, in years, months and days
// Lennon was born on October 9, 1940.
BigDate birthDate = new BigDate( 1940, 10, 9 );
BigDate today = BigDate.localToday();
int[] age = BigDate.age( birthDate, today );
System.out
.println( "Today John Lennon would be "
+ age[ 0 ]
+ " years and "
+ age[ 1 ]
+ " months and "
+ age[ 2 ]
+ " days old." );
}
sep();
{
// How long since John Lennon died, in years, months and days
// Lennon was born on December 8, 1980.
BigDate deathDate = new BigDate( 1980, 12, 8 );
BigDate today = BigDate.localToday();
int[] age = BigDate.age( deathDate, today );
System.out
.println( "It has been "
+ age[ 0 ]
+ " years and "
+ age[ 1 ]
+ " months and "
+ age[ 2 ]
+ " days since John Lennon was murdered." );
}
sep();
{
// Precisely how old is are the Bush twins in years, months
and days
// There were born on 1981-11-25.
BigDate birthDate = new BigDate( 1981, 11, 25 );
BigDate today = BigDate.localToday();
int[] age = BigDate.age( birthDate, today );
System.out
.println( "Today fraternal twins Barbara and Jenna
Bush are "
+ age[ 0 ]
+ " years and "
+ age[ 1 ]
+ " months and "
+ age[ 2 ]
+ " days old." );
System.out
.println( "or "
+ ( today.getOrdinal() -
birthDate.getOrdinal() )
+ " days." );
}
sep();
{
// Dr. Paul Norman was killed in plane crash
// on the Sunday before Friday 2004-07-02. What date was that?
BigDate deathDate = new BigDate( 2004, 7, 2 );
deathDate
.setOrdinal( deathDate.getOrdinal() - 5 /* Friday */ +
0
/* Sunday */ );
System.out
.println( "Dr. Paul Norman was killed in a plane crash
on "
+ deathDate
+ "." );
}
sep();
{
// How much time elapsed after Hitler died before George W.
Bush was
// born.
BigDate hitler = new BigDate( 1945, 5, 1 );
BigDate bush = new BigDate( 1946, 7, 6 );
int[] age = BigDate.age( hitler, bush );
System.out
.println( "George W. Bush was born "
+ age[ 0 ]
+ " years and "
+ age[ 1 ]
+ " months and "
+ age[ 2 ]
+ " days after Hitler died on 1945-05-01" );
System.out
.println( "or "
+ ( bush.getOrdinal() - hitler.getOrdinal()
)
+ " days." );
}
sep();
{
// Precisely how old was Hillary Clinton (born 1947-10-26)
// when Sir Edmund Hillary climbed
// mount everent in 1953-05-29 in years, months and days
BigDate birthDate = new BigDate( 1947, 10, 26 );
BigDate climb = new BigDate( 1953, 5, 29 );
int[] age = BigDate.age( birthDate, climb );
System.out
.println( "Hillary Clinton was "
+ age[ 0 ]
+ " years and "
+ age[ 1 ]
+ " months and "
+ age[ 2 ]
+ " days old when Sir Edmund Hillary climbed
Mount Everest on 1953-05-29" );
System.out
.println( "or "
+ ( climb.getOrdinal() -
birthDate.getOrdinal() )
+ " days." );
}
sep();
{
// What day of the week was Jesus born on?
// assume Jesus was born on December 25, 0001.
// Scholars assure us he was NOT actually born then.
int dayOfWeek = BigDate.dayOfWeek( BigDate.toOrdinal( 1, 12,
25 ) );
String[] daysOfTheWeek =
{"Sunday",
"Monday",
"Tuesday",
"Wednesday",
"Thursday",
"Friday",
"Saturday"};
String dayName = daysOfTheWeek[ dayOfWeek ];
System.out.println( "Jesus was born on a " + dayName + "." );
}
sep();
{
// How much time elapsed between December 25 4 BC and April
30, 28
// AD
BigDate fromDate = new BigDate( -4, 12, 25 );
BigDate toDate = new BigDate( 28, 4, 30 );
System.out.println( "How long did Jesus live?" );
System.out
.println( toDate.getOrdinal() - fromDate.getOrdinal()
+ " days elapsed between 0004/12/25 BC and
0028/04/30 AD," );
int[] age = BigDate.age( fromDate, toDate );
System.out
.println( "or put another way, "
+ age[ 0 ]
+ " years and "
+ age[ 1 ]
+ " months and "
+ age[ 2 ]
+ " days." );
}
sep();
{
// Precisely how old is George Bush Jr., in years, months and
days
// George Bush Jr. was born on July 6. 1946.
BigDate birthDate = new BigDate( 1946, 7, 6 );
BigDate today = BigDate.localToday();
int[] age = BigDate.age( birthDate, today );
System.out
.println( "Today George Bush Jr. is "
+ age[ 0 ]
+ " years and "
+ age[ 1 ]
+ " months and "
+ age[ 2 ]
+ " days old." );
}
sep();
{
// Precisely how old is Saddam Hussein, in years, months and
days
// Saddam Hussein was born on April 28, 1937.
BigDate birthDate = new BigDate( 1937, 4, 28 );
BigDate today = BigDate.localToday();
int[] age = BigDate.age( birthDate, today );
System.out
.println( "Today Saddam Hussein. is "
+ age[ 0 ]
+ " years and "
+ age[ 1 ]
+ " months and "
+ age[ 2 ]
+ " days old." );
}
sep();
{
// How Many days after bin Laden's last documented meeting
with the
// CIA
// was the World Trade attack?
BigDate fromDate = new BigDate( 2001, 7, 1 ); // 2001-07-01
BigDate toDate = new BigDate( 2001, 9, 11 ); // 2001-09-11
System.out
.println( "The World Trade attack occurred "
+ ( toDate.getOrdinal() -
fromDate.getOrdinal() )
+ " days after Osmama bin Laden's last
meeting with the CIA." );
}
sep();
{
// How long ago was the World Trade Center destroyed?
// The attack was 2001-09-11.
BigDate hitDate = new BigDate( 2001, 9, 11 );
BigDate today = BigDate.localToday();
int[] age = BigDate.age( hitDate, today );
System.out
.println( "The World Trade center was destroyed "
+ age[ 0 ]
+ " years and "
+ age[ 1 ]
+ " months and "
+ age[ 2 ]
+ " days ago." );
}
sep();
{
// How long did it take Bush to give up trying to catch bin
Laden.
// The attack was 2001-09-11.
// On 2002-03-13 Bush announced:
// I don't know where he is. I have no idea and I really don't
care.
// It's not that important. It's not our priority.
BigDate hitDate = new BigDate( 2001, 9, 11 );
BigDate giveUpDate = new BigDate( 2002, 3, 13 );
int[] patience = BigDate.age( hitDate, giveUpDate );
System.out
.println( "Bush officially gave up chasing bin Laden
after "
+ patience[ 0 ]
+ " years, "
+ patience[ 1 ]
+ " months and "
+ patience[ 2 ]
+ " days." );
}
sep();
{
// What was the date and day of week 72 days prior to
Lincoln's
// assassination?
BigDate assassinDate = new BigDate( 1865, 4, 18 ); //
1865-04-18
BigDate priorDate = new BigDate( assassinDate.getOrdinal() -
72 );
int dayOfWeek = priorDate.getDayOfWeek();
final String[] daysOfTheWeek =
{"Sunday",
"Monday",
"Tuesday",
"Wednesday",
"Thursday",
"Friday",
"Saturday"};
System.out
.println( "72 days prior to Lincoln's assassination
was "
+ priorDate.toString()
+ ", a "
+ daysOfTheWeek[ dayOfWeek ] );
}
sep();
{
// how long has it been since since John F. Kennedy was
// assassinated?
// John F. Kennedy was assassinated on November 22, 1963
System.out
.println( "John F. Kennedy was assassinated "
+ ( BigDate.localToday().getOrdinal()
- BigDate.toOrdinal( 1963, 11, 22 ) )
+ " days ago." );
}
sep();
{
// How long after Martin Luther King's assassination
// was Bobby Kennedy assassinated?
// MLK was assassinated April 4, 1968.
// RK was assassinated June 4, 1968.
System.out
.println( "Robert Kennedy was assassinated "
+ ( BigDate.toOrdinal( 1968, 6, 4 )
- BigDate.toOrdinal( 1968, 4, 4 ) )
+ " days after Martin Luther King." );
}
sep();
{
// How old would Martin Luther King be if he were still alive
today?
// MLK was born 1929-01-15, celebrated 3rd monday in January
BigDate mlk = new BigDate( 1929, 1, 15 );
BigDate today = BigDate.localToday();
int[] age = BigDate.age( mlk, today );
System.out
.println( "Martin Luther King would be "
+ age[ 0 ]
+ " years and "
+ age[ 1 ]
+ " months and "
+ age[ 2 ]
+ " days old today." );
}
sep();
{
// Mysterious missing days in the calendar.
// Pope Gregory: 1582 Oct 4 Thursday, was followed immediately
// by 1582 Oct 15 Friday dropping 10 days.
//
// British: 1752 Sep 2 Wednesday was followed immediately
// by 1752 Sep 14 Thursday dropping 12 days.
BigDate priorDate;
BigDate afterDate;
if ( BigDate.isBritish )
{
System.out
.println(
"According to the
British/American/Canadian calendar, 12 days were dropped." );
priorDate = new BigDate( 1752, 9, 2 );
afterDate = new BigDate( 1752, 9, 14 );
}
else
{
System.out
.println(
"According to Pope Gregory's calendar, 10
days were dropped." );
priorDate = new BigDate( 1582, 10, 4 );
afterDate = new BigDate( 1582, 10, 15 );
}
final String[] daysOfTheWeek =
{"Sunday",
"Monday",
"Tuesday",
"Wednesday",
"Thursday",
"Friday",
"Saturday"};
int dayOfWeek = priorDate.getDayOfWeek();
System.out
.println( priorDate.toString()
+ " was a "
+ daysOfTheWeek[ dayOfWeek ]
+ "." );
dayOfWeek = afterDate.getDayOfWeek();
System.out
.println( afterDate.toString()
+ " was a "
+ daysOfTheWeek[ dayOfWeek ]
+ "." );
}
pause();
{
// What is the Julian Day number of various dates 1970/1/1
// Cross check these with the US Naval Observatory at:
// http://aa.usno.navy.mil/AA/data/docs/JulianDate.html
BigDate d = new BigDate( 2000, 3, 20 );
System.out
.println(
"Astronomical Julian Propleptic calendar day
for 2000/03/20 is "
+ d.getProplepticJulianDay() );
d = new BigDate( 1970, 1, 1 );
System.out
.println(
"Astronomical Julian Propleptic calendar day
for 1970/01/01 is "
+ d.getProplepticJulianDay() );
d = new BigDate( 1600, 1, 1 );
System.out
.println(
"Astronomical Julian Propleptic calendar day
for 1600/01/01 is "
+ d.getProplepticJulianDay() );
d = new BigDate( 1500, 1, 1 );
System.out
.println(
"Astronomical Julian Propleptic calendar day
for 1500/01/01 is "
+ d.getProplepticJulianDay() );
d = new BigDate( 1, 1, 1 );
System.out
.println(
"Astronomical Julian Propleptic calendar day
for 0001/01/01 is "
+ d.getProplepticJulianDay() );
d = new BigDate( -1, 12, 31 );
System.out
.println(
"Astronomical Julian Propleptic calendar day
for -0001/12/31 is "
+ d.getProplepticJulianDay() );
d = new BigDate( -6, 1, 1 );
System.out
.println(
"Astronomical Julian Propleptic calendar day
for -0006/01/01 is "
+ d.getProplepticJulianDay() );
d = new BigDate( -4713, 1, 1 );
System.out
.println(
"Astronomical Julian Propleptic calendar day
for -4713/01/01 is "
+ d.getProplepticJulianDay() );
}
pause();
{
// How long till Christmas? ( Sun's way.)
// this code will give a negative number just after Christmas.
System.out
.println( "Your child asks, how long is it until
Christmas?" );
System.out
.println(
"Here are the possible answers you might give
to an American child" );
GregorianCalendar now = new GregorianCalendar();
int thisYear = now.get( Calendar.YEAR );
// You may open presents at 7 AM December 25, local time
System.out
.println(
"You may open your presents at 7 AM Christmas
morning." );
GregorianCalendar christmas =
new GregorianCalendar( thisYear, 12 - 1, 25, 7, 0, 0
);
// millis since 1970 Jan 1
long christmasTimeStamp = christmas.getTime().getTime();
long nowTimeStamp = now.getTime().getTime();
final int MILLISECONDS_PER_DAY = 24 * 60 * 60 * 1000;
double dayUnitsDiff =
( christmasTimeStamp - nowTimeStamp )
/ (double) MILLISECONDS_PER_DAY;
System.out
.println( "1. It is "
+ dayUnitsDiff
+ " day units of 24 hours until you may open
your presents." );
System.out
.println( "2. It is "
+ Math.ceil( dayUnitsDiff )
+ " day units of 24 hours rounded up until
you may open your presents." );
System.out
.println( "3. It is "
+ Math.round( dayUnitsDiff )
+ " day units of 24 hours rounded until you
may open your presents." );
System.out
.println( "4. It is "
+ Math.floor( dayUnitsDiff )
+ " day units of 24 hours rounded down until
you may open your presents." );
int gmtChristmasOrdinal =
(int) ( christmasTimeStamp / MILLISECONDS_PER_DAY );
int gmtNowOrdinal = (int) ( nowTimeStamp /
MILLISECONDS_PER_DAY );
int gmtDiffInDays = gmtChristmasOrdinal - gmtNowOrdinal;
System.out
.println( "5. Children in Greenwich have "
+ gmtDiffInDays
+ " sleeps (midnight crossings) to go
until\n"
+ "you may open your presents.\n"
+ "They may open theirs even sooner." );
// For children living in the USA, the timezone offset will be
// negative.
// days since 1970 Jan 1
// There is no GregorianCalender.getOffset or
// get(ADJUSTED_ZONE_OFFSET);
int christmasZoneOffset =
christmas.get( Calendar.ZONE_OFFSET )
+ now.get( Calendar.DST_OFFSET );
int localChristmasOrdinal =
(int) ( ( christmasTimeStamp + christmasZoneOffset )
/ MILLISECONDS_PER_DAY );
int nowZoneOffset =
now.get( Calendar.ZONE_OFFSET )
+ now.get( Calendar.DST_OFFSET );
int localNowOrdinal =
(int) ( ( nowTimeStamp + nowZoneOffset )
/ MILLISECONDS_PER_DAY );
int localDiffInDays = localChristmasOrdinal - localNowOrdinal;
System.out
.println( "6. You have "
+ localDiffInDays
+ " sleeps (midnight crossings) to go." );
}
{
// how long till Christmas? ( with BigDate. )
// this code will give a negative number just after Christmas.
BigDate today = BigDate.localToday();
BigDate christmas = new BigDate( today.getYYYY(), 12, 25 );
System.out
.println( "7. Uncle Roedy's Bigdate says it is "
+ ( christmas.getOrdinal() -
today.getOrdinal() )
+ " sleeps until Christmas." );
int[] age = BigDate.age( today, christmas );
System.out
.println( "8. Or put another way "
+ age[ 0 ]
+ " years and "
+ age[ 1 ]
+ " months and "
+ age[ 2 ]
+ " days to go." );
}
--
Canadian Mind Products, Roedy Green.
http://mindprod.com Java custom programming, consulting and coaching.