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https://issues.apache.org/jira/browse/LANG-1109?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14514852#comment-14514852
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Benedikt Ritter commented on LANG-1109:
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I'm not sure this belongs into lang. What do others think?
> Number percentage formatting with fractional digits
> ---------------------------------------------------
>
> Key: LANG-1109
> URL: https://issues.apache.org/jira/browse/LANG-1109
> Project: Commons Lang
> Issue Type: New Feature
> Components: lang.*
> Reporter: Marco Janc
> Fix For: Discussion
>
>
> Java built-in number formatter does formats Number locale aware with
> fractional digits defined by the defined scale of the Number, aswell the
> required precision (trims trailing zeros).
> For some reason Java's built-in percentage number formatter does not formats
> fractional digits. So i wrote a function which has same behavior as the Java
> built-in number formatter but with percentage formatting.
> {code:java}
> /**
> * Formats the given Number as percentage with necessary precision.
> * This serves as a workaround for {@link
> NumberFormat#getPercentInstance()} which does not renders fractional
> * digits.
> *
> * @param number
> * @param locale
> *
> * @return
> */
> public static String formatPercentFraction(final Number number, final
> Locale locale)
> {
> if (number == null)
> return null;
> // get string representation with dot
> final String strNumber =
> NumberFormat.getNumberInstance(Locale.US).format(number.doubleValue());
> // create exact BigDecimal and convert to get scale
> final BigDecimal dNumber = new
> BigDecimal(strNumber).multiply(new BigDecimal(100));
> final NumberFormat percentScaleFormat =
> NumberFormat.getPercentInstance(locale);
> percentScaleFormat.setMaximumFractionDigits(Math.max(0,
> dNumber.scale()));
> // convert back for locale percent formatter
> return percentScaleFormat.format(dNumber.multiply(new
> BigDecimal(0.01)));
> }
> {code}
> I also unit tested it with many inputs.
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