The i18n Cookbook - recipies for a global society

 Problem:

You know what parts of a date you want to display but you don't know the exact pattern to use.

Solution:

Often a Java programmer will know what type of pattern he wants, but not exactly what the pattern would be.  With icu4j's DateTimePatternGenerator you can specify a pattern skeleton, and it will return the most appropriate localized match.

To get the best pattern for the skeleton, "MMMddYYYYH" in Japanese:

//Get a Locale object

ULocale locale = new ULocale("ja_JP");

//Get an instance of the DatePatternGenerator for the locale

DateTimePatternGenerator dp = DateTimePatternGenerator.getInstance(locale);

//Get the best pattern match

String best = dp.getBestPattern("MMMddYYYYHH");

//output the best pattern match

System.out.println(best);

//Get a DateFormat for the pattern

DateFormat df = new SimpleDateFormat(best);

//output a formatted date

System.out.println(df.format(new Date()));

The output:

YYYY年MM月dd日 HH

2008年12月06日 15

As you can see the closest match uses a 4 digit year followed by a year symbol, a 2 digit month followed by a month symbol, a 2 digit day followed by a day symbol, and a 0~24 hour.