RFR 8218228 : The constructor StringBuffer(CharSequence) violates spec for negatively sized argument

[David Holmes]

On 8/02/2019 11:59 am, Ivan Gerasimov wrote:
> Hi David!
> 
> 
> On 2/7/19 5:16 PM, David Holmes wrote:
>> Hi Ivan,
>>
>> On 8/02/2019 11:02 am, Ivan Gerasimov wrote:
>>> Hello!
>>>
>>> The specification states:
>>> """
>>> If the length of the specified CharSequence is less than or equal to 
>>> zero, then an empty buffer of capacity 16 is returned.
>>> """
>>>
>>> However, the current implementation throws either 
>>> NegativeArraySizeException or IndexOutOfBounds instead (the actual 
>>> exception type depends on the value of reported negative length).
>>
>> How can you have a negative length CharSequence ??
>>
> A custom CharSequence returning negative length() can be created.
> Not sure how useful/popular this may be, though.

Seems pretty meaningless so just treating that as an error seems fine. 
Though somewhat debatable whether you need to add an appropriate @throws.

> That's why I propose just removing the mentioning negative length, and 
> not changing the behavior.
> 
> The proposed code change is to only unify the behavior for any negative 
> value of length.

Ok.

>> If its an empty CharSequence then it should return the empty buffer as 
>> indicated.
>>
> Empty CharSequence is processed correctly already.

Okay so by removing this part:

-      * <p>
-      * If the length of the specified {@code CharSequence} is
-      * less than or equal to zero, then an empty buffer of capacity
-      * {@code 16} is returned.

you're relying on the main specification to implicitly handle the empty 
case.

David
-----

> With kind regards,
> Ivan
> 
>> Cheers,
>> David
>>
>>> It is proposed to do two things:
>>> 1) remove the problematic sentence from the javadoc (CSR is filed).
>>> 2) unify the exception type thrown, if the argument reports negative 
>>> length.
>>> NegativeArraySizeException will be consistent with, for example, 
>>> StringBuffer(negativeCapacity).
>>>
>>> Would you please help review the fix?
>>>
>>> BUGURL: https://bugs.openjdk.java.net/browse/JDK-8218228
>>> WEBREV: http://cr.openjdk.java.net/~igerasim/8218228/00/webrev/
>>> CRS: https://bugs.openjdk.java.net/browse/JDK-8218649
>>>
>>
>