ConcurrentHashMap/ConcurrentMap/Map.compute (original) (raw)

Doug Lea dl at cs.oswego.edu
Thu Dec 6 13:10:36 PST 2012

On 12/06/12 07:29, Doug Lea wrote:

Actually, it would be a ConcurrentMap spec change, which is definitely crossing the line. It will take some further thought to see if there is a spec/wording that is both safe and useful.

Not so hard. All of the "The default implementation is equivalent to:" specs and wordings are now completely compatible with those in ConcurrentMap (which could use a few tiny touchups someday to clarify this).

This omits the what would have been a nice symmetry about replace(k, null) and computeIfPresent. The only interpretation that works is for replace in non-null-accepting maps to throw NPE here. Which is what the j.u.c Maps now do anyway.

I put a viewable version of the javadocs (using JDK7 javadoc) at http://gee.cs.oswego.edu/dl/wwwtmp/apis/Map.html (With nested standin versions of Function interfaces decls for now.) Comments welcome.

I suspect that the style/terminology here of documenting defaults by saying they are equivalent to code snippets will usually be the most informative/useful tactic. It seems to be more understandable than the AbstractCollection etc style of trying to say it all in words.

-Doug

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