1. Number Formats Number formats vary in different cultures
Group (e.g. thousands) and decimal separators e.g. 1, (US) vs 1 234,56 (France)
Negative numbers e.g (US) vs 123- (Arabic)
Number formats are locale-sensitive.
Number formats should be presented correctly for a user’s / customer’s locale.

2. Currency Different name Different symbol Fractional currency?
Dollars, Cents
Decimal System?
Typically, however…
Mauritania
Ouguiya is divided into 5 khoum
Madagascar
Malegasy ariary is divided into 5 iraimbilanja
Example of the importance of correct currency formats:
Cost of an article of clothing: $123,56 [English (United States)]
Cost of a car: $25.345,99 [Portuguese (Brazil)]

3. Currency Sign dollar sign U+0024 $ pound sign U+00A3 £
yen sign U+00A5 ¥
yen character U+5186 円
euro sign U+20AC €
thai baht sign U+0E3F ฿
french franc sign U+20A3 ₣
lira sign U+20A4 ₤
Source:

4. Currency Placement Canadian French 123,45 $ Canadian English $123.45
Currency is a suffix
Canadian English $123.45
Currency is a prefix
Canadian Inuktitut $123.45
Currency in Nunavut is written same as English.
Source:

5. Fractional Separators
Portuguese Escudos 12$34ESC
Fractional separator is dollar sign
German Deutsch Marks 12,34DM
Fractional separator is comma
Canadian Dollars (English) $12.34
Fractional separator is full-stop
Canadian Dollars (French) 12,34 $
Swiss Numbers 12'345,67
Swiss Francs SFr 12'345.67
Source:

6. Grouping
British 1,234,567,890.12
Groups of 3
Chinese,Japanese 12億 3456万 or 12億 3,456万 7,890.12
Groups of 4, separated by ideographic characters and optionally a thousands separator.
Indian 1,23,45,67,890.12
One group of 3, then groups of 2
German ,12
Groups of 3, separator is full-stop
Swiss 1'234'567'890,12
Groups of 3, separator is apostrophe
French ,12
Groups of 3, separator is a thin non-breaking space
Source:

7. Other issues Rounding List Separators Number Width
Round up? Round down?
Rounding should follow local conventions
Largely application specific…
List Separators
1.23,4.56,7.89
1,23,4,56,7,89
Number Width
Different currencies will require different number width fields.

8. Java Number Formatting
Java Class NumberFormat
NumberFormat is the abstract base class for all number formats.
This class provides the interface for formatting and parsing numbers.
NumberFormat also provides methods for determining which locales have number formats, and what their names are.

9. Java Number Formatting cont.
static NumberFormat getCurrencyInstance()
Returns a currency format for the current default locale.
static NumberFormat getCurrencyInstance(Locale inLocale)
Returns a currency format for the specified locale.
static NumberFormat getInstance()
Returns the default number format for the current default locale.
static NumberFormat getInstance(Locale inLocale)
Returns the default number format for the specified locale.
static NumberFormat getIntegerInstance()
Returns an integer number format for the current default locale.
static NumberFormat getIntegerInstance(Locale inLocale)
Returns an integer number format for the specified locale.
static NumberFormat getNumberInstance()
Returns a general-purpose number format for the current default locale.
static NumberFormat getNumberInstance(Locale inLocale)
 Returns a general-purpose number format for the specified locale.
static NumberFormat getPercentInstance()
Returns a percentage format for the current default locale.
static NumberFormat getPercentInstance(Locale inLocale)
Returns a percentage format for the specified locale.

10. Java Number Formatting cont.
Number to String
NumberFormat nf = NumberFormat.getNumberInstance();
// Or use a specific locale
// getIntegerInstance(Locale inLocale)
double quantity = ;
String strQuantity = nf.format(quantity);
System.out.println(strQuantity);
12,

11. Java Number Formatting cont.
String to Number
NumberFormat nf = NumberFormat.getNumberInstance();
// Or use a specific locale
// getIntegerInstance(Locale inLocale)
String strQuantity = ;
Number num = nf.parse(strQuantity);

12. Java Number Formatting cont.
Alignment, particularly important for currency
int columnWidth = 10;
double number = ;
StringBuffer strNumber = new StringBuffer();
FieldPosition pos = new FieldPosition(NumberFormat.INTEGER_FIELD);
nf.format(number, strNumber, pos);
// Retrieve the updated index to the decimal point.
index = pos.getEndIndex();
int pad = columnWidth - index;
char[] padChars = new char[pad];
for (int x = 0; x< pad; x++) {
padChars[x] = ' '; }
strNumber.insert(0, padChars);
println(strNumber.toString());

13. Java Number Formatting cont.
Java Class DecimalFormat
DecimalFormat is a concrete subclass of NumberFormat that formats decimal numbers.
A DecimalFormat comprises a pattern and a set of symbols.
The pattern may be set directly using applyPattern(), or indirectly using the API methods.
When using the NumberFormat factory methods, the pattern and symbols are read from localized ResourceBundles.

14. Number Formatting Patterns
Symbol Location Localized? Meaning
0 Number Yes Digit
# Number Yes Digit, zero shows as absent
. Number Yes Decimal separator or monetary decimal separator
- Number Yes Minus sign
, Number Yes Grouping separator
E Number Yes Separates mantissa and exponent in scientific notation. Need not be quoted in prefix or suffix.
; Subpattern boundary Yes Separates positive and negative subpatterns
% Prefix or suffix Yes Multiply by 100 and show as percentage
\u2030 Prefix or suffix Yes Multiply by 1000 and show as per mille
¤ (\u00A4) Prefix or suffix No Currency sign, replaced by currency symbol. If doubled, replaced by international currency symbol. If present in a pattern, the monetary decimal separator is used instead of the decimal separator.
' Prefix or suffix No Used to quote special characters in a prefix or suffix, for example, "'#'#" formats 123 to "#123". To create a single quote itself, use two in a row: "# o''clock".

15. A DecimalFormat pattern contains a positive and negative subpattern.
Each subpattern has a prefix, numeric part, and suffix.
For example, "#,##0.00;(#,##0.00)".
BNF
pattern := subpattern{;subpattern}
subpattern := {prefix}integer{.fraction}{suffix}
prefix := '\\u0000'..'\\uFFFD' - specialCharacters
suffix := '\\u0000'..'\\uFFFD' - specialCharacters
integer := '#'* '0'* '0'
fraction := '0'* '#'*

16. Example Patterns The 0 symbol shows a digit or 0 if no digit present
NumberFormat formatter = new DecimalFormat("000000");
String s = formatter.format( ); //
Notice that the number was rounded up
The # symbol shows a digit or nothing if no digit present
formatter = new DecimalFormat("##");
s = formatter.format( ); // -1235
s = formatter.format(0); // 0
formatter = new DecimalFormat("##00");
s = formatter.format(0); // 00
The . symbol indicates the decimal point
formatter = new DecimalFormat(".00");
s = formatter.format(-.567); // -.57
formatter = new DecimalFormat(".######");
s = formatter.format( ); //
formatter = new DecimalFormat("# ");
s = formatter.format( ); //

17. Example Patterns Cont. The , symbol is used to group numbers
formatter = new DecimalFormat("#,###,###");
s = formatter.format( ); // -1,235
s = formatter.format( ); // -1,234,568
The ; symbol is used to specify an alternate pattern for negative values
formatter = new DecimalFormat("#;(#)");
s = formatter.format( ); // (1235)
The ' symbol is used to quote literal symbols
formatter = new DecimalFormat("'#'#");
s = formatter.format( ); // -#1235
formatter = new DecimalFormat("'abc'#");
s = formatter.format( ); // -abc1235

18. Dates This is based on the "Java Internationalization" book
Dates come in many formats, even in the US:
10/4/99; October 4, 1999; 4 Oct 99; etc
In different languages and locales these are expressed differently
e.g. 4 octobre 1999 in France
The names of the days and months change
Capitalization rules differ:
January in English, janvier in French
Order of components varies:
day/month in Aus, month/day in the US
What date is this?
03/04/02

19. Java Date Formatting DateFormat class
The standard Java class for handling dates and times in different locales
The static method DateFormat.getDateInstance() will get a date format object
The parameters are the date format (short, medium, long, full) and a locale
DateFormat df = DateFormat.getDateInstance(DateFormat.FULL, Locale.FRANCE);
To get a formatted string out of this, pass in a Date object to format()
String result = df.format(new Date());

20. Java Date Formatting
The same class is used to format times using DateFormat.getTimeInstance()
... and get both a time and date formatter by DateFormat.getDateTimeInstance()

21. Display length SHORT is completely numeric MEDIUM is longer
or 3:30pm
MEDIUM is longer
Jan 12, 1952
LONG is longer still
January 12, 1952 or 3:30:32pm
FULL is pretty completely specified
Tuesday, April 12, 1952 AD or 3:30:42pm PST.

22. Example DateFormat output
U.S. Locale German Locale
DEFAULT 3:58:45 PM 15:58:45
SHORT 3:58 PM 15:58
MEDIUM 3:58:45 PM 15:58:45
LONG 3:58:45 PM PDT 15:58:45 GMT+02:00
FULL 3:58:45 oclock PM PDT Uhr GMT+02:00

23. Java Date Formatting cont.
Defining your own format
SimpleDateFormat is a concrete class for formatting and parsing dates in a locale-sensitive manner.
getTimeInstance, getDateInstance, or getDateTimeInstance in DateFormat provides formatters for default date formatting.
SimpleDateFormat allows user-defined patterns for date- time formatting.
However, you may modify the format pattern using the applyPattern methods as desired.

24. Date Formatting Patterns
Letter Date or Time Component Presentation Examples
G Era designator Text AD [AD / CE or BC/BCE?]
y Year Year ; 96
M Month in year Month July; Jul; 07
w Week in year Number 27
W Week in month Number 2
D Day in year Number 189
d Day in month Number 10
F Day of week in month Number 2
E Day in week Text Tuesday; Tue
a Am/pm marker Text PM
H Hour in day (0-23) Number 0
k Hour in day (1-24) Number 24
K Hour in am/pm (0-11) Number 0
h Hour in am/pm (1-12) Number 12
m Minute in hour Number 30
s Second in minute Number 55
S Millisecond Number 978
z Time zone General time zone Pacific Standard Time; PST; GMT-08:00
Z Time zone RFC 822 time zone -0800

25. Date Formatting Patterns
"yyyy.MM.dd G 'at' HH:mm:ss z“ -> AD at 12:08:56 PDT
"EEE, MMM d, ''yy" -> Wed, Jul 4, '01
"h:mm a" -> 12:08 PM
"hh 'o''clock' a, zzzz" -> 12 o'clock PM, Pacific Daylight Time
"K:mm a, z" -> 0:08 PM, PDT
"yyyyy.MMMMM.dd GGG hh:mm aaa" -> July.04 AD 12:08 PM
"EEE, d MMM yyyy HH:mm:ss Z" -> Wed, 4 Jul :08:
"yyMMddHHmmssZ" ->

26. Parsing Dates
while ((dateString != null) && (dateString.length() > 0)) {
try
Date date = format.parse(dateString);
System.out.println("Original string: " dateString);
System.out.println("Parsed date : " date.toString());
System.out.println(); // Skip a line }
catch(ParseException pe)
System.out.println("ERROR: could not parse date in string \"" + dateString + "\"");
// Read another string
System.out.print("ENTER DATE STRING: ");
dateString = reader.readLine();

27. Calendars Solar Calendar Julian Calendar
Solar calendars assign a date to each solar day. A day may consist of the period between sunrise and sunset, with a following period of night.
Julian Calendar
It has a regular year of 365 days divided into 12 months, and a leap day is added every 4 years, hence the average Julian year is days.
The calendar remained in use into the 20th century in some countries and is still used by many national Orthodox churches.
Unfortunately, Earth's tropical year is a little less than days (it is approximately days), so this calendar, slowly drifted out of sync with the seasons. Hence, the Gregorian calendar was later adopted by most of the West, starting in 1582, and it has since become the world's dominant civic calendar.

28. Calendars cont. Gregorian Calendar
Defacto International standard
Lunar calendars
A lunar calendar is a calendar whose date indicates the moon phase.
Islamic calendar
A lunisolar calendar is a calendar whose date indicates both the moon phase and the season.
Hebrew calendar
Chinese calendar
Tibetan calendar
and some Hindu calendars.

29. Calendars cont. Fiscal calendars
A fiscal calendar fixes each month at a specific number of weeks to facilitate comparisons from month to month and year to year.
January always has exactly 5 weeks (Sunday through Saturday), February has 4 weeks, March has 4 weeks, etc.
ISO 8601

30. Java Calendar Class
A Date object represents a specific instant in time with millisecond precision.
Whereas, a Calendar is an abstract base class for converting between a Date object and a set of integer fields such as YEAR, MONTH, DAY, HOUR, and so on.
Subclasses of Calendar interpret a Date according to the rules of a specific calendar system.
The Java platform provides one concrete subclass of Calendar: GregorianCalendar

31. Calendar Examples Computing a persons age
Calendar dateOfBirth = new GregorianCalendar(1972, Calendar.JANUARY, 27);
Calendar today = Calendar.getInstance();
int age = today.get(Calendar.YEAR) - dateOfBirth.get(Calendar.YEAR);
// Add the tentative age to the date of birth to get this year's birthday
dateOfBirth.add(Calendar.YEAR, age);
// If this year's birthday has not happened yet, subtract one from age
if (today.before(dateOfBirth)) {
age--; }

32. Calendar Examples cont.
Before / After
Calendar xmas = new GregorianCalendar(1998, Calendar.DECEMBER, 25);
Calendar newyears = new GregorianCalendar(1999, Calendar.JANUARY, 1);
// Determine which is earlier
boolean b = xmas.after(newyears); // false
b = xmas.before(newyears); // true
// Get difference in milliseconds
long diffMillis = newyears.getTimeInMillis()-xmas.getTimeInMillis();
// Get difference in seconds
long diffSecs = diffMillis/(1000); //
// Get difference in minutes
long diffMins = diffMillis/(60*1000); // 10080
// Get difference in hours
long diffHours = diffMillis/(60*60*1000); // 168
// Get difference in days
long diffDays = diffMillis/(24*60*60*1000); // 7
Note: Is there a better way of doing this?

33. Calendar Examples cont.
Day of the week
The day-of-week is an integer value where 1 is Sunday, 2 is Monday, ..., and 7 is Saturday
Calendar xmas = new GregorianCalendar(1998, Calendar.JANUARY, 25);
int dayOfWeek = xmas.get(Calendar.DAY_OF_WEEK);
// 6=Friday
Calendar cal = new GregorianCalendar(2003, Calendar.JANUARY, 1);
dayOfWeek = cal.get(Calendar.DAY_OF_WEEK);
// 4=Wednesday

34. Time Zones

35. Time Zones cont. Solar time.
When the sun reaches its highest point in the sky, it is noon. Different cities had different times…
As telecommunications improved and with the expansion of the railways this became increasingly awkward.
Time zones are generally centered on meridians of a longitude that is a multiple of 15° thus making neighboring time zones one hour apart.
However, the one hour separation is not universal and, as the map demonstrates.
All time zones are defined relative to Coordinated Universal Time (UTC).
The reference point for Time Zones is the Prime Meridian (longitude 0°) which passes through the Royal Greenwich Observatory in Greenwich, London, England.
Greenwich Mean Time (GMT).

36. Time Zones cont. Los Angeles, California, USA: UTC − 8
(e.g. if it is 12:00 UTC, then it is 04:00 in Los Angeles)
Toronto, Ontario, Canada: UTC − 5
(e.g. if it is 11:00 UTC, then it is 06:00 in Toronto)
Stockholm, Sweden: UTC + 1
(e.g. if it is 12:00 UTC, then it is 13:00 in Stockholm)
Melbourne, Japan: UTC + 10
(e.g. if it is 11:00 UTC, then it is 21:00 in Tokyo)
Note: The time zone adjustment for a specific location may vary due to the use of daylight saving time.
e.g. New Zealand which is usually UTC + 12, observes a one-hour daylight saving time adjustment during the southern hemisphere summer resulting in a local time of UTC + 13!

37. Daylight savings Pros Cons Energy conservation
“United States Department of Transportation studies showed that DST reduces the country's electricity usage by one percent during each day DST is in effect.”
Increased opportunities for outdoor activities & decreased crime.
Cons
Agriculture – the cows don’t follow it.

38. Java Time Zones Java Class TimeZone
TimeZone represents a time zone offset, and also figures out daylight savings.
SimpleTimeZone is a concrete subclass of TimeZone that represents a time zone for use with a Gregorian calendar.
The class holds an offset from GMT, called raw offset, and start and end rules for a daylight saving time schedule.

39. Java Time Zones cont. Get the current time in Hong Kong
Calendar cal = new GregorianCalendar(TimeZone.getTimeZone("Hongkong"));
int hour12 = cal.get(Calendar.HOUR); // 0..11
int minutes = cal.get(Calendar.MINUTE); // 0..59
int seconds = cal.get(Calendar.SECOND); // 0..59
boolean am = cal.get(Calendar.AM_PM) == Calendar.AM;
Get the current hour-of-day at GMT
cal.setTimeZone(TimeZone.getTimeZone("GMT"));
int hour24 = cal.get(Calendar.HOUR_OF_DAY); // 0..23
Get the current local hour-of-day
cal.setTimeZone(TimeZone.getDefault());
hour24 = cal.get(Calendar.HOUR_OF_DAY); // 0..23

40. Java Time Zones cont.
Does the time zone have a daylight savings time period?
boolean hasDST = tz.useDaylightTime();
Is the time zone currently in a daylight savings time?
boolean inDST = tz.inDaylightTime(today);