Date and Time Formatting Examples

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Format

The ICU DateFormat interface enables you to format a date in milliseconds into a string representation of the date. Also, the interface enables you to parse the string back to the internal date representation in milliseconds.

C++

DateFormat* df = DateFormat::createDateInstance();

UnicodeString myString;

UDate myDateArr[] = { 0.0, 100000000.0, 2000000000.0 };

for (int32_t i = 0; i < 3; ++i) {

myString.remove();

cout << df->format( myDateArr[i], myString ) << endl;

}

C

/* 1st example: format the dates in millis 100000000 and

2000000000 */

UErrorCode status=U_ZERO_ERROR;

int32_t i, myStrlen=0;

UChar* myString;

UDate myDateArr[] = { 0.0, 100000000.0, 2000000000.0 }; // test values

UDateFormat* df = udat_open(UCAL_DEFAULT, UCAL_DEFAULT, NULL, "GMT", &status);

for (i = 0; i < 3; ++i) {

myStrlen = udat_format(df, myDateArr[i], NULL, myStrlen, NULL, &status);

if(status==U_BUFFER_OVERFLOW_ERROR){

status=U_ZERO_ERROR;

myString=(UChar*)malloc(sizeof(UChar) * (myStrlen+1) );

udat_format(df, myDateArr[i], myString, myStrlen+1, NULL, &status);

printf("%s\n", austrdup(myString) );

/* austrdup( a function used to convert UChar* to char*) */

free(myString);

}

Parse

To parse a date for a different locale, specify it in the locale call. This call creates a formatting object.

C++

DateFormat* df = DateFormat::createDateInstance

( DateFormat::SHORT, Locale::getFrance());

C

/* 2nd example: parse a date with short French date/time

formatter */

UDateFormat* df = udat_open(UDAT_SHORT, UDAT_SHORT, "fr_FR", "GMT", &status);

UErrorCode status = U_ZERO_ERROR;

int32_t parsepos=0;

UDate myDate = udat_parse(df, myString, u_strlen(myString), &parsepos,

&status);

Java

import java.text.FieldPosition;

import java.text.ParseException;

import java.util.Calendar;

import java.util.Date;

import java.util.Locale;

import com.ibm.icu.text.DateFormat;

public class TestDateTimeFormat {

public void run() {

// Formatting Dates

DateFormat dfUS = DateFormat.getDateInstance(DateFormat.FULL, Locale.US);

DateFormat dfFrance = DateFormat.getDateInstance(DateFormat.FULL, Locale.FRANCE);

StringBuffer sb = new StringBuffer();

Calendar c = Calendar.getInstance();

Date d = c.getTime();

sb = dfUS.format(d, sb, new FieldPosition(0));

System.out.println(sb.toString());

StringBuffer sbf = new StringBuffer();

sbf = dfFrance.format(d, sbf, new FieldPosition(0));

System.out.println(sbf.toString());

StringBuffer sbg = new StringBuffer();

DateFormat dfg = DateFormat.getDateTimeInstance(DateFormat.FULL, DateFormat.SHORT);

FieldPosition pos = new FieldPosition(DateFormat.MINUTE_FIELD);

sbg = dfg.format(d, sbg, pos);

System.out.println(sbg.toString());

System.out.println(sbg.toString().substring(pos.getBeginIndex(), pos.getEndIndex()));

// Parsing Dates

String dateString_US = "Thursday, February 7, 2008";

String dateString_FRANCE = "jeudi 7 février 2008";

try {

Date parsedDate_US = dfUS.parse(dateString_US);

Date parsedDate_FRANCE = dfFrance.parse(dateString_FRANCE);

System.out.println(parsedDate_US.toString());

System.out.println(parsedDate_FRANCE.toString());

} catch (ParseException pe) {

System.out.println("Exception while parsing :" + pe);

}

public static void main(String args[]) {

new TestDateTimeFormat().run();

}

Getting Specific Date Fields

To get specific fields of a date, you can use the FieldPosition function for C++ or UFieldPosition function for C.

C++

UErrorCode status = U_ZERO_ERROR;

FieldPosition pos(DateFormat::YEAR_FIELD)

UDate myDate = Calendar::getNow();

UnicodeString str;

DateFormat* df = DateFormat::createDateInstance

( DateFormat::LONG, Locale::getFrance());

df->format(myDate, str, pos, status);

cout << pos.getBeginIndex() << "," << pos. getEndIndex() << endl;

C

UErrorCode status = U_ZERO_ERROR;

UFieldPosition pos;

UChar *myString;

int32_t myStrlen = 0;

char buffer[1024];

pos.field = 1; /* Same as the DateFormat::EField enum */

UDateFormat* dfmt = udat_open(UCAL_DEFAULT, UCAL_DEFAULT, NULL, "PST",

&status);

myStrlen = udat_format(dfmt, myDate, NULL, myStrlen, &pos, &status);

if (status==U_BUFFER_OVERFLOW_ERROR){

status=U_ZERO_ERROR;

myString=(UChar*)malloc(sizeof(UChar) * (myStrlen+1) );

udat_format(dfmt, myDate, myString, myStrlen+1, &pos, &status);

}

printf("date format: %s\n", u_austrcpy(buffer, myString));

buffer[pos.endIndex] = 0; // NULL terminate the string.

printf("UFieldPosition position equals %s\n", &buffer[pos.beginIndex]);

DateTimePatternGenerator

This class lets you get a different variety of patterns, such as month+day. The following illustrates this in Java, C++ and C.

Java

// set up the generator

DateTimePatternGenerator generator

= DateTimePatternGenerator.getInstance(locale);

// get a pattern for an abbreviated month and day

final String pattern = generator.getBestPattern("MMMd");

SimpleDateFormat formatter = new SimpleDateFormat(pattern, locale);

// use it to format (or parse)

String formatted = formatter.format(new Date());

// for French, the result is "13 sept."

C++

// set up the generator

status = U_ZERO_ERROR;

DateTimePatternGenerator *generator = DateTimePatternGenerator::createInstance( locale, status);

if (U_FAILURE(status)) {

return;

}

// get a pattern for an abbreviated month and day

UnicodeString pattern = generator->getBestPattern(UnicodeString("MMMd"), status);

SimpleDateFormat *formatter = new SimpleDateFormat(pattern, locale, status);

// use it to format (or parse)

UnicodeString formatted;

formatted = formatter->format(Calendar::getNow(), formatted, status);

// for French, the result is "13 sept."

C

const UChar skeleton[]= {'M', 'M', 'M', 'd', 0};

status=U_ZERO_ERROR;

generator=udatpg_open(locale, &status);

if(U_FAILURE(status)) {

return;

}

/* get a pattern for an abbreviated month and day */

length = udatpg_getBestPattern(generator, skeleton, 4,

pattern, patternCapacity, &status);

formatter = udat_open(UDAT_IGNORE, UDAT_DEFAULT, locale, NULL, -1,

pattern, length, &status);

/* use it to format (or parse) */

formattedCapacity = (int32_t)(sizeof(formatted)/sizeof((formatted)[0]));

resultLen=udat_format(formatter, ucal_getNow(), formatted, formattedCapacity,

NULL, &status);

/* for French, the result is "13 sept." */

Changing the TimeZone Formatting Style

It also contains some helper functions for parsing patterns. Here's an example of replacing the kind of timezone used in a pattern.

Java

/**

* Replace the zone string with a different type, eg v's for z's, etc.

* <p>Called with a pattern, such as one gotten from

* <pre>

* String pattern = ((SimpleDateFormat)

* DateFormat.getTimeInstance(style, locale)).toPattern();

* </pre>

* @param pattern original pattern to change, such as "HH:mm zzzz"

* @param newZone Must be: z, zzzz, Z, ZZZZ, v, vvvv, V, or VVVV

* @return

*/

public String replaceZoneString(String pattern, String newZone) {

DateTimePatternGenerator.FormatParser formatParser =

new DateTimePatternGenerator.FormatParser();

final List itemList = formatParser.set(pattern).getItems();

boolean found = false;

for (int i = 0; i < itemList.size(); ++i) {

Object item = itemList.get(i);

if (item instanceof VariableField) {

// the first character of the variable field determines the type,

// according to CLDR.

String variableField = item.toString();

switch (variableField.charAt(0)) {

case 'z': case 'Z': case 'v': case 'V':

if (!variableField.equals(newZone)) {

found = true;

itemList.set(i, new VariableField(newZone));

}

break;

}

return found ? formatParser.toString() : pattern;

}