Name: rmT116609 Date: 05/15/2002


FULL PRODUCT VERSION :
java version "1.4.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-b92)
Java HotSpot(TM) Client VM (build 1.4.0-b92, mixed mode)

FULL OPERATING SYSTEM VERSION :

Windows NT Version 4.0

A DESCRIPTION OF THE PROBLEM :
The javadoc for method java.text.DecimalFormat.getDecimalFormatSymbols() states:

"Returns the decimal format symbols, which is generally not changed by the programmer or user."

However, the source code reads:

  public DecimalFormatSymbols getDecimalFormatSymbols() {
    try {
      // don't allow multiple references
      return (DecimalFormatSymbols) symbols.clone();
    } catch (Exception foo) {
      return null; // should never happen
    }
  }

In other words, the user of the function does not get a reference to the DecimalFormatSymbols used in the DecimalFormat's "symbols" field, but a reference to a copy.

The documentation should clearly state this, or the function should return a reference to the "symbols" field.

Such behaviour makes (possibly reasonable) code such as this pointless:

  DecimalFormat f = getTheFormat();
  DecimalFormatSymbols s = f.getDecimalFormatSymbols();
  s.setDecimalSeparator(',');

One wonders what the advantage of forcing the programmer to adopt this rather longwinded workaround is:

  DecimalFormat f = getTheFormat();
  DecimalFormatSymbols s = f.getDecimalFormatSymbols();
  s.setDecimalSeparator(',');
  f.setDecimalFormatSymbols(s);

However, my real gripe is about the time I've lost trying to understand why my changes to the DecimalFormat weren't working. A developer without source-code at hand would not find the necessary information (that a clone() call is
involved) in the documentation.

This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;

public class A {
  public static void main(final String args[]) {
    DecimalFormat f = new DecimalFormat();
    f.getDecimalFormatSymbols().setDecimalSeparator('X');
    char separator = f.getDecimalFormatSymbols().getDecimalSeparator();
    System.out.println(separator);
  }
}
---------- END SOURCE ----------
(Review ID: 146600)
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