Proposal: ArrayList constructor perforrmance improvement

Stuart Marks stuart.marks at
Tue Dec 18 22:01:30 UTC 2018

On 12/18/18 9:23 AM, Martin Buchholz wrote:
> The blessed solution to the list copy problem is probably List.copyOf
> which might do the optimization you're hoping for.

List.copyOf is fine, but note that it returns an instance of an unmodifiable 
List. The main optimization it does is that if it's asked to make a copy of an 
already-unmodifiable list, it simply returns its argument.

If you want an actual ArrayList instead of an unmodifiable list, of course 
you'll have to use the ArrayList copy constructor or some variation.


More information about the core-libs-dev mailing list