[icu-design] Rounding to -0

[Stuart G. <icu...@gm...>]

I have done some investigation on the issue from today's ICU meeting on the
rounding up of small numbers between -1 and 0 exclusive to -0.
http://bugs.icu-project.org/trac/ticket/8302

It appears that this change to the rounding behaviour was done in response
to http://bugs.icu-project.org/trac/ticket/7609 This change also appears to
be to match JDK behaviour.

So, in the following code taken from NumberFormatTest.java (DecimalFormat
below is com.ibm.icu.text.DecimalFormat):

           DecimalFormat df = (DecimalFormat) NumberFormat.getInstance();

        df.setRoundingMode(MathContext.ROUND_HALF_UP); // whether the
rounding is set or not the result is the same

        df.setMinimumFractionDigits(1);

        df.setMaximumFractionDigits(1);

        String text1 = df.format(-0.01);


The contents of text1 are "-0".

This is the same for this JDK code:

           java.text.DecimalFormat jdf = (java.text.DecimalFormat)
java.text.NumberFormat.getInstance();

        //jdf.setRoundingMode(MathContext.ROUND_HALF_UP);

        jdf.setMinimumFractionDigits(1);

        jdf.setMaximumFractionDigits(1);

        String jtext1 = jdf.format(-0.01);

The contents of jtext1 are "-0".

So, this still leaves the question open then of what should a user do if
they don't want "-0" but instead want what perhaps 99% of users want which
is "0" all the time? Is there an existing way to do this? If not, perhaps we
need API to do so?

Thanks,
Stuart