<i18n dev> RFR: 8314604: j.text.DecimalFormat behavior regarding patterns is not clear

[Naoto Sato]

On Fri, 18 Aug 2023 21:28:34 GMT, Justin Lu <jlu at openjdk.org> wrote:

> Please review this PR and [CSR](https://bugs.openjdk.org/browse/JDK-8314607) which clarifies the behavior of patterns  in regards to the max integer digits in j.text.DecimalFormat.
> 
> The current specification (of `applyPattern`) states that patterns do not set the value of max integer digits. This is incorrect, these methods/constructors do set a value for the max integer digits. If the pattern is in scientific notation, the max integer digits value is derived from the pattern. Otherwise, the pattern is ignored, and the limit is set to `Integer.MAX_VALUE`.
> 
> See below,
> 
> DecimalFormat df = new DecimalFormat();
> df.applyPattern("000.000E0");
> df.getMaximumIntegerDigits(); //  ==> 3
> df.applyPattern("000.000");
> df.getMaximumIntegerDigits(); // ==> 2147483647
> 
> DecimalFormat df = new DecimalFormat("000.000");
> df.getMaximumIntegerDigits(); // ==> 2147483647
> DecimalFormat df = new DecimalFormat("000.000E0");
> df.getMaximumIntegerDigits(); // ==> 3
> 
> 
> Method descriptions should be fixed, and the relevant constructors need to mention the behavior as well.

src/java.base/share/classes/java/text/DecimalFormat.java line 458:

> 456:      * is the typical end-user desire. Use {@link #setMaximumIntegerDigits(int)}
> 457:      * if you want to set a specific limit to integer digits when the
> 458:      * given pattern is not in scientific notation.

It could be simpler if the normal case (Integer.MAX_VALUE) comes first, then the scientific notation case in which you can refer to the max integer digit in the class description. Also, `setMaximumIntegerDigits` can be called on a scientific notation as well, correct?

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PR Review Comment: https://git.openjdk.org/jdk/pull/15349#discussion_r1309181469