Trail: Internationalization
Lesson: Formatting
Section: Dates and Times

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Changing Date Format Symbols

Version note: This Date and Time section uses the date and time APIs in the java.util package. The java.time APIs, available in the JDK 8 release, provides a comprehensive date and time model that offers significant improvements over the java.util classes. The java.time APIs are described in the Date Time trail. The Legacy Date-Time Code page might be of particular interest.

The format method of the SimpleDateFormat class returns a String composed of digits and symbols. For example, in the String "Friday, April 10, 2009," the symbols are "Friday" and "April." If the symbols encapsulated in SimpleDateFormat don't meet your needs, you can change them with the DateFormatSymbols. You can change symbols that represent names for months, days of the week, and time zones, among others. The following table lists the DateFormatSymbols methods that allow you to modify the symbols:

`DateFormatSymbol` Methods
Setter Method	Example of a Symbol the Method Modifies
`setAmPmStrings`	PM
`setEras`	AD
`setMonths`	December
`setShortMonths`	Dec
`setShortWeekdays`	Tue
`setWeekdays`	Tuesday
`setZoneStrings`	PST

The following example invokes setShortWeekdays to change the short names of the days of the week from lowercase to uppercase characters. The full source code for this example is in DateFormatSymbolsDemo. The first element in the array argument of setShortWeekdays is a null String. Therefore the array is one-based rather than zero-based. The SimpleDateFormat constructor accepts the modified DateFormatSymbols object as an argument. Here is the source code:

Date today;
String result;
SimpleDateFormat formatter;
DateFormatSymbols symbols;
String[] defaultDays;
String[] modifiedDays;

symbols = new DateFormatSymbols( new Locale("en", "US"));
defaultDays = symbols.getShortWeekdays();

for (int i = 0; i < defaultDays.length; i++) {
    System.out.print(defaultDays[i] + " ");
}
System.out.println();

String[] capitalDays = {
    "", "SUN", "MON",
    "TUE", "WED", "THU",
    "FRI", "SAT"
};
symbols.setShortWeekdays(capitalDays);

modifiedDays = symbols.getShortWeekdays();
for (int i = 0; i < modifiedDays.length; i++) {
    System.out.print(modifiedDays[i] + " ");
}
System.out.println();
System.out.println();

formatter = new SimpleDateFormat("E", symbols);
today = new Date();
result = formatter.format(today);
System.out.println("Today's day of the week: " + result);

The preceding code generates this output:

 Sun Mon Tue Wed Thu Fri Sat 
 SUN MON TUE WED THU FRI SAT 

Today's day of the week: MON

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