Java: Format number in millions

Here's a subclass of NumberFormat that I whipped up. It looks like it does the job but I'm not entirely sure it's the best way:

private static final NumberFormat MILLIONS = new NumberFormat()
{
    private NumberFormat LOCAL_REAL = new DecimalFormat("#,##0.00M");

    public StringBuffer format(double number, StringBuffer toAppendTo, FieldPosition pos)
    {
        double millions = number / 1000000D;
        if(millions > 0.1) LOCAL_REAL.format(millions, toAppendTo, pos);

        return toAppendTo;
    }

    public StringBuffer format(long number, StringBuffer toAppendTo, FieldPosition pos)
    {
        return format((double) number, toAppendTo, pos);
    }

    public Number parse(String source, ParsePosition parsePosition)
    {
        throw new UnsupportedOperationException("Not implemented...");
    }
};

Note that if you have a BigDecimal, you can use the movePointLeft method:

new DecimalFormat("#.00").format(value.movePointLeft(6));

String.format("%.2fM", theNumber/ 1000000.0);

For more information see the String.format javadocs.