RFR 8218227 : StringBuilder constructor throws confusing NegativeArraySizeException

[Roger Riggs]

Hi Ivan,

A good boundary condition to clean up.

Should tests for StringBuffer be added too?

Maxing out the length at MAX_VALUE must always result in an OOM.
If such an allocation were to succeed, it would violate the specified 
initial capacity requirement.

Thanks, Roger


On 02/02/2019 02:28 AM, Ivan Gerasimov wrote:
> Hello!
>
> The spec of the constructors 
> StringBuilder(String)/StringBuilder(CharSequence) states that the 
> initial capacity of the builder will be set to the length of the 
> argument plus 16.
> This causes them to throw confusing NegativeArraySizeException when 
> the argument's length is close to Integer.MAX_VALUE.
>
> Let the arguments length be (Integer.MAX_VALUE - DELTA), like in the 
> code below:
>
>         String str = "Z".repeat(Integer.MAX_VALUE - DELTA);
>         StringBuilder sb = new StringBuilder(str);
>
> Currently the behavior is as following:
>     0 <= DELTA <= 2 - unable to construct str,
>     2 <= DELTA <= 15 - NegativeArraySizeException is thrown,
>     16 <= DELTA <= 17 - OutOfMemoryError is thrown,
>     DELTA >= 18 - works fine.
>
> With the fix, OOM will be thrown for all DELTA <= 17.
>
> Also the fix will make constructing a StringBuilder from UTF16 coded 
> String slightly more efficient.
>
> BUGURL: https://bugs.openjdk.java.net/browse/JDK-8218227
> WEBREV: http://cr.openjdk.java.net/~igerasim/8218227/00/webrev/
>
> Would you please help review the fix?
>