On 22/11/2013 4:17 AM, Louis Wasserman wrote:
The Javadoc for
Map.merge<http://download.java.net/jdk8/docs/api/java/util/Map.html#merge-K-V-java.util.function.BiFunction->states
that its default implementation is equivalent to:
V oldValue = map.get(key);
V newValue = (oldValue == null) ? value :
remappingFunction.apply(oldValue, value);
if (newValue == null)
map.remove(key);
else if (oldValue == null)
map.remove(key);
else
map.put(key, newValue);
I'm somewhat confused by the second branch of this if statement, which is
reached if newValue is nonnull and oldValue is null. Does this really
*remove* the entry for that key? I would have expected there to be only
two branches: either remove the entry if newValue is null, or put newValue
if it's nonnull.
There seems to be a hole in the spec regarding how a null value
parameter is handled. The default implementation treats it as-if the
remappingFunction returns null. Not unreasonable but not specified.
David