RFR - 6480539: BigDecimal.stripTrailingZeros() should specify no-op on zero BigDecimals

[Paul Sandoz]

On Feb 5, 2013, at 1:05 AM, Joseph Darcy <joe.darcy at oracle.com> wrote:
> 
> On 2/4/2013 1:36 PM, Stephen Colebourne wrote:
>> On 4 February 2013 19:31, Joe Darcy <joe.darcy at oracle.com> wrote:
>>> The stripTrailingZeros method has acted in this surprising way since the
>>> IBM-led JSR 13 was integrated into the platform back in JDK 5, which shipped
>>> in 2004.
>>> 
>>> This situation is analogous to when the specification and behavior disagree.
>>> Our general policy to resolve such cases when evolving the JDK is:
>>> 
>>> "..., there are times in evolving the JDK when differences are found between
>>> the specified behavior and the actual behavior (for example 4707389,
>>> 6365176). The two basic approaches to fixing these bugs are to change the
>>> implementation to match the specified behavior or to change the
>>> specification (in a platform release) to match the implementation's (perhaps
>>> long-standing) behavior; often the latter option is chosen since it has a
>>> lower de facto impact on behavioral compatibility."
>>> http://cr.openjdk.java.net/~darcy/OpenJdkDevGuide/OpenJdkDevelopersGuide.v0.777.html
>>> 
>>> If this issue were being addressed before JDK 5 shipped or even during JDK
>>> 6, I would support changing the behavior of stripTrailingZeros.  However,
>>> for addressing this in JDK 8, I think it is more appropriate to keep the
>>> behavior as-is and document this special case.
>> I don't see what JDK 5 vs 6 vs 8 really has to do with it.
> 
> The longer a particular behavior has been in a shipped JDK release, the more likely it is various people have built code that depend on that behavior.
> 

This is one of those unfortunate cases where a bug can become a feature.

Sometimes it is useful when evaluating to obtain empirical data on how much such a feature is used e.g. analysing jars from public maven repos:

http://grepcode.com/search/usages?type=method&id=repository.grepcode.com%24java%24root@jdk%24openjdk@7-b147@java%24math@BigDecimal@stripTrailingZeros%28%29&k=u

Of course i have no idea of the internals of BigDecimal and what knock on effects such a change would have.

Paul.