FULL PRODUCT VERSION :
java version "1.6.0_20"
Java(TM) SE Runtime Environment (build 1.6.0_20-b02)
Java HotSpot(TM) Client VM (build 16.3-b01, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [version 5.1.2600]

EXTRA RELEVANT SYSTEM CONFIGURATION :
user.language=fr


A DESCRIPTION OF THE PROBLEM :
Class sun.text.resources.FormatData_fr
declares
 { "NumberPatterns",
                new String[] {
                    "#,##0.###;-#,##0.###", // decimal pattern
                    "#,##0.00 \u00A4;-#,##0.00 \u00A4", // currency pattern
                    "#,##0 %" // percent pattern
                }
            },
and
 { "NumberElements",
                new String[] {
                    ",", // decimal separator
...
}

Meaning that according NumberPatterns, a decimal number in french is 12.34 (wrong) but according to NumberElements, is 12,34 (right).

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
in a main method:

DecimalFormatSymbols s = DecimalFormatSymbols.getInstance(new Locale("fr"));
NumberFormat nf = new DecimalFormat("##.####", s);
double d = 53.1234567;
System.err.println(nf.format(d));


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
53,1235
ACTUAL -
53.1235

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
manually format