Hi Mark,
AFAIKS computeIfAbsent does what we want:
<http://docs.oracle.com/javase/8/docs/api/java/util/Map.html#computeIfAbsent-K-java.util.function.Function->
It seems that putIfAbsent would not though. This is indeed confusing.
I wish putIfAbsent had been specified similarly to
computeIfAbsent...
best regards,
-- daniel
ConcurrentHashMap seems to have something more
On 5/12/14 1:33 PM, Mark Sheppard wrote:
If I read the javdoc correctly neither computeIfAbsent nor putIfAbsent
seem to match the
previous semantics of the if statement?
computeIfAbsent: "If the value for the specified key is present and
non-null, attempts to compute a new mapping given the key and its
current mapped value."
or
"If the specified key is not already associated with a value (or is
mapped to |null|), attempts to compute its value using the given mapping
function and enters it into this map unless |null|. "
my interpretation is this is relevant if value if there exist a value
and you want to update?
putIfAbsent: "If the specified key is not already associated with a
value (or is mapped to |null|) associates it with the given value and
returns |null|, else returns the current value."
in this case we can have null value returned
previous semantics were if the PM doesn't exist then instantiate and
cache it in the hashtable. return the PM - no null value returned
maybe I'm misinterpreting the docs
regards
Mark
On 12/05/2014 08:52, Seán Coffey wrote:
Good tip Alan/Chris.
I'll make that change and push.
Regards,
Sean.
On 12 May 2014 07:17:04 GMT+01:00, Alan Bateman
<alan.bate...@oracle.com> wrote:
On 11/05/2014 21:56, Seán Coffey wrote:
Now that JDK 8 is the official build bootstrap JDK for JDK 9, we can
remove use of reflection in ORB code to access the applet context.
bug report : https://bugs.openjdk.java.net/browse/JDK-8042906
webrev : http://cr.openjdk.java.net/~coffeys/webrev.8042906/webrev/
I agree with Chris that computeIfAbsent is best here, that was also the
suggestion back in early April before the bootstrapping issue came up.
In any case, it's good you are re-visiting this to clean it up.
-Alan
