TreeMap specific override of putIfAbsent/merge

[Paul Sandoz]

Hi Tomasz,

If there was any rejection it was probably due to time constraints than for any technical reasons.

It should be easy to refactor the TreeMap.put implementation into say a private putVal accepting a boolean argument and both put and putIfAbsent call putVal (same pattern as in HashMap).

The compute* methods may require separate implementations with almost duplicated kind of patterns.

An OCA [1] compliant patch would be appreciated, which should also include updates to relevant tests where appropriate.

Thanks,
Paul.

[1] http://www.oracle.com/technetwork/community/oca-486395.html <http://www.oracle.com/technetwork/community/oca-486395.html>

> On 20 May 2016, at 15:19, Tomasz Kowalczewski <tomasz.kowalczewski at gmail.com> wrote:
> 
> Hi all,
> 
> TreeMap does not have its own specific overrides of Map methods that were
> added in java 8. In our specific usage we do what is effective a merge
> operation:
> 
> For incoming K and V:
> 1. get value from map
> 2. if present - merge with incoming value V
> 3. if absent - associate K with V in the map
> 
> For case where K is not in the map we traverse the tree map it twice.
> Implementing TreeMap specific override of putIfAbsent would allow as to
> avoid this cost.
> 
> Was such change considered in past and rejected? Is anyone interested in a
> patch that implements it?
> 
> --
> Regards,
> Tomasz Kowalczewski