RFR: 8319174: Enhance robustness of some j.m.BigInteger constructors [v3]

[Roger Riggs]

On Thu, 2 Nov 2023 14:25:20 GMT, Raffaello Giulietti <rgiulietti at openjdk.org> wrote:

>> Enhance `java.math.BigInteger` constructors taking a `byte[]` argument by improving guarantees of internal invariants.
>
> Raffaello Giulietti has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Restored ordering of exceptions.

src/java.base/share/classes/java/math/BigInteger.java line 344:

> 342:      * @param  len the number of bytes to use.
> 343:      * @throws NumberFormatException {@code val} is zero bytes long,
> 344:      *         or {@code len} is zero.

I would be concerned about the compatibility impact on existing applications.
Though (very) uncommon, an existing application be using a non-zero length array and a len of zero to represent zero.
With this change it will throw an unexpected exception.

src/java.base/share/classes/java/math/BigInteger.java line 4707:

> 4705:         ++from;
> 4706:         /* Skip leading -1 bytes. */
> 4707:         for (; b == -1 && from < to; b = a[from++]);  //empty body

The style for an empty body in this file seems to be a ";" on a line by itself. 
The comment make it explicit but visually it might stand out more on a separate line. 
(My preferred style is `{}` with enough visual space to make it stand out.)

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PR Review Comment: https://git.openjdk.org/jdk/pull/16449#discussion_r1380843814
PR Review Comment: https://git.openjdk.org/jdk/pull/16449#discussion_r1380839094