Java Reference
In-Depth Information
// Format a double value for an Italian locale
result
= format.getInstance(Locale.ITALIAN).format(83.404);
System.out.println(result);
// Parse a String into a Number
try {
Number num = format.parse("75.736");
System.out.println(num);
} catch (java.text.ParseException ex){
System.out.println(ex);
}
To format using a pattern, the
DecimalFormat
class can be used along with
NumberFormat
. In the solution to this recipe, you saw that creating a new
Decim-
alFormat
instance by passing a pattern to its constructor would return a
Number-
Format
type. This is because
DecimalFormat
extends the
NumberFormat
class.
Because the
NumberFormat
class is abstract,
DecimalFormat
contains all the
functionality that
NumberFormat
contains, plus added functionality for working with
patterns. Therefore, it can be used to work with different formats from the locales just
as you have seen in the previous demonstration. This provides the ultimate flexibility
when working with
double
or
long
formatting.
As mentioned previously, the
DecimalFormat
class can take a string-based pat-
tern in its constructor. You can also use the
applyPattern()
method to apply a pat-
tern after the fact. Each pattern contains a prefix, numeric part, and suffix, which allow
you to format a particular decimal value to the required precision and include leading
digits and commas as needed. The symbols used to build patterns are displayed in
Table 4-3
. Each of the patterns also contains a positive and negative subpattern. These
two subpatterns are separated by a semicolon (
;
) and the negative subpattern is option-
al. If there is no negative subpattern present, the localized minus sign is used. For in-
stance, a complete pattern example would be
###,##0.00;(###,##0.00)
.
Character
Description
#
Digit; blank if no digit is present
