It's just a pointer to where the settings are in the JRE. Gary
On Sat, Jun 12, 2021, 10:20 sebb <seb...@gmail.com> wrote: > On Sat, 12 Jun 2021 at 14:00, Gary Gregory <garydgreg...@gmail.com> wrote: > > > > FTR: java.text.DecimalFormatSymbols > > Huh? > AFAICT the code does not use that class, so I have no idea what your > reply means. > > > Gary > > > > On Sat, Jun 12, 2021, 08:46 sebb <seb...@gmail.com> wrote: > > > > > On Sat, 12 Jun 2021 at 12:58, Matt Juntunen <matt.juntu...@hotmail.com > > > > > wrote: > > > > > > > > Hello, > > > > > > > > I mentioned a while ago the idea of moving a utility that I find > quite > > > useful from commons-geometry to commons-text, which would be a more > > > appropriate home for it. There was not any interest at the time but > I've > > > made a few improvements to the class and I'd like to try again. The > utility > > > in question is the DoubleFormats [1] class. This class contains factory > > > methods for producing lightweight, thread-safe DoubleFunction<String> > > > instances for converting doubles to decimal strings in different > formats. > > > The class is specifically designed for data output; no localization is > > > performed. > > > > > > No localisation? > > > Not even decimal point? > > > > > > > It is used in commons-geometry to provide a way to control the > precision > > > and formatting of double values in text-based geometric data formats > such > > > as OBJ. I've found that although the JDK provides a number of different > > > ways to format doubles (eg, String.format, DecimalFormat, BigDecimal, > etc), > > > none of them have fit the requirements for performant, thread-safe data > > > output. Hence, the reason for this class. > > > > > > > > Below are examples of each of the types of formats available and some > > > outputs. The arguments passed to each method are the precision (maximum > > > number of non-zero decimal digits) and min exponent (base 10 exponent > for > > > the smallest non-zero number that should be represented). > > > > > > > > // plain decimal representation; no scientific format > > > > DoubleFunction<String> plain = DoubleFormats.createPlain(5, -3); > > > > plain.apply(1); // 1.0 > > > > plain.apply(1e10); // 10000000000.0 > > > > plain.apply(1234.567); // 1234.6 > > > > plain.apply(0.00356); // 0.004 > > > > > > > > // scientific format > > > > DoubleFunction<String> sci = DoubleFormats.createScientific(5, -3); > > > > sci.apply(1); // 1.0 > > > > sci.apply(1e10); // 1.0E10 > > > > sci.apply(1234.567); // 1.2346E3 > > > > sci.apply(0.00356); // 4.0E-3 > > > > > > > > // engineering format > > > > DoubleFunction<String> eng = DoubleFormats.createEngineering(5, -3); > > > > eng.apply(1); // 1.0 > > > > eng.apply(1e10); // 10.0E9 > > > > eng.apply(1234.567); // 1.2346E3 > > > > eng.apply(0.00356); // 4.0E-3 > > > > > > > > // default format; uses the Double.toString() convention of > representing > > > > // numbers less that 10^-3 or greater than 10^7 using scientific > format > > > and > > > > // other numbers using plain decimal format > > > > DoubleFunction<String> def = DoubleFormats.createDefault(5, -3); > > > > def.apply(1); // 1.0 > > > > def.apply(1e10); // 1.0E10 > > > > def.apply(1234.567); // 1234.6 > > > > def.apply(0.00356); // 0.004 > > > > > > > > > > > > The performance of all of these methods is comparable to > DecimalFormat > > > or BigDecimal. The benchmark output below shows the results of > formatting > > > 10000 double values using standard Double.toString(), a simple > BigDecimal > > > conversion, DecimalFormat (single instance), and a function returned > from > > > DoubleFormats.createDefault(). Double.toString() is the clear winner > but > > > the rest are all quite close. > > > > > > > > Benchmark (size) Mode Cnt > > > Score Error Units > > > > DoubleFormatsPerformance.doubleToString 10000 avgt 5 > > > 3837610.399 ± 62668.705 ns/op > > > > DoubleFormatsPerformance.bigDecimal 10000 avgt 5 > > > 6279807.365 ± 93566.619 ns/op > > > > DoubleFormatsPerformance.decimalFormat 10000 avgt 5 > > > 5787717.633 ± 168626.950 ns/op > > > > DoubleFormatsPerformance.doubleFormatsDefault 10000 avgt 5 > > > 5779534.166 ± 69496.434 ns/op > > > > > > > > Please let me know if there is any interest in moving this class to > > > commons-text. It's primary advantages are that it is > > > > -thread-safe (unlike DecimalFormat), > > > > -performant (unlike String.format()), and > > > > -allows a variety of output formats (unlike BigDecimal). > > > > > > > > I would also be open to discussion and improvements on the > > > design/implementation. > > > > > > > > Regards, > > > > Matt J > > > > > > > > [1] > > > > https://github.com/apache/commons-geometry/blob/master/commons-geometry-io-core/src/main/java/org/apache/commons/geometry/io/core/utils/DoubleFormats.java > > > > > > --------------------------------------------------------------------- > > > To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org > > > For additional commands, e-mail: dev-h...@commons.apache.org > > > > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org > For additional commands, e-mail: dev-h...@commons.apache.org > >
