How can I set date and time formatting in Java that respects the user's OS settings

Question

I am running my Java app on a Windows 7 machine where my regional settings are set up to format dates as YYYY-mm-dd and time as HH:mm:ss (e.g. "2011-06-20 07:50:28"). But when I use DateFormat.getDateTimeInstance().format to format my date I do not see that instead I get "20-Jun-2011 7:50:28 AM". What do I need to do to format dates in the way that my customers have their OS setup to display dates?

Here is what my code in question looks like:

File selGameLastTurnFile = selectedGame.getLastTurn ().getTurnFile ();
Date selGameModifiedDate = new Date (selGameLastTurnFile.lastModified());
if (selectedGame.isYourTurn ())  {
    gameInfo = Messages.getFormattedString ("WhoseTurnIsIt.Prompt.PlayTurn",  //$NON-NLS-1$
            FileHelper.getFileName (selGameLastTurnFile), 
            DateFormat.getDateTimeInstance().format(selGameModifiedDate));
}  else  {
    gameInfo = Messages.getFormattedString ("WhoseTurnIsIt.Prompt.SentTurn",  //$NON-NLS-1$
            selGameLastTurnFile.getName (), 
            DateFormat.getDateTimeInstance().format(selGameModifiedDate));
}

The Messages.getFormattedString calls are using MessageFormat to put the date into a sentence that will look like this:

Play the turn 'QB Nat vs Ian 008' (received 20-Jun-2011 7:50:28 AM)

However my OS settings are setup to format the date as I described above and I expected to see this:

Play the turn 'QB Nat vs Ian 008' (received 2011-06-20 07:50:28)

I searched here and other Java programming sites and could not find the answer but this seems like such an obvious thing to want to do that I feel like I am missing something obvious.

Answer 1

First you have to tell Java what your system LOCALE looks like.

Check Java System.
String locale = System.getProperty("user.language")

And then format the date accordinly (SimpleDateFormat)
SimpleDateFormat(String pattern, Locale locale)

Refer to the practical Java code for a working example...

String systemLocale = System.getProperty("user.language");
String s;
Locale locale; 

locale = new Locale(systemLocale );
s = DateFormat.getDateInstance(DateFormat.MEDIUM, locale).format(new Date());
System.out.println(s);
// system locale is PT outputs 16/Jul/2011

locale = new Locale("us");
s = DateFormat.getDateInstance(DateFormat.MEDIUM, locale).format(new Date());
System.out.println(s);
// outputs Jul 16, 2011

locale = new Locale("fr");
s = DateFormat.getDateInstance(DateFormat.MEDIUM, locale).format(new Date());
System.out.println(s);
// outputs 16 juil. 2011