I experimented with putting null value into ConcurrentHashMap which led me
to this code:
final V putVal(K key, V value, boolean onlyIfAbsent) {
if (key == null || value == null) throw new NullPointerException();
I agree that getting NPE this way is not user friendly.
Using Java 8, the notion of null value support would be conveyed to user in
a friendly manner.
Cheers
On Fri, Jul 13, 2018 at 5:51 PM Colin McCabe <cmcc...@apache.org> wrote:
> On Fri, Jul 13, 2018, at 17:45, Ted Yu wrote:
>
> Looking at modifyConfigs API, it doesn't seem that ConcurrentHashMap
> should be used as the underlying parameter type.
>
>
> I agree that there are other types of maps that do support null values.
> However, the fact that some official map implementations from the standard
> library don't support null values makes this a questionable feature to rely
> on. Imagine being a new user of this API who created a ConcurrentHashMap,
> tried to insert some null keys, and pass to the API. It would compile,
> but not work. It would certainly be confusing.
>
> Anyway, to signify that null value is supported, value type can be
> declared as Optional<Config>.
>
> FYI
>
>
> Yeah, now that we're on Java 8, Optional could be a good choice here.
>
> best,
> Colin
>
>
> On Fri, Jul 13, 2018 at 5:35 PM Colin McCabe <cmcc...@apache.org> wrote:
>
>
> Hi Ted,
>
> That’s a fair question. I think the main reason I didn’t propose that
> originally is that many people find null values in maps confusing. Also,
> some newer java maps don’t support null values, such as ConcuurentHashMap.
> I’m curious what others think about this.
>
> Best,
> Colin
>
> On Wed, Jul 11, 2018, at 21:28, Ted Yu wrote:
> > bq. Map<ConfigResource, Config> changes, Set<ConfigResource>
> removals,
> >
> > Is it possible to combine the two parameters into one Map where null
> Config
> > value signifies removal of config ?
> > This way, the following wouldn't occur (reducing un-intended config
> > removal):
> >
> > bq. If a configuration key is specified in both *changes* and *removals*
> >
> > *Cheers*
> >
> > On Wed, Jul 11, 2018 at 10:54 AM Colin McCabe <cmcc...@apache.org>
> wrote:
> >
> > > Hi all,
> > >
> > > Previously, we discussed some issues with alterConfigs here on the
> mailing
> > > list, and eventually came to the conclusion that the RPC as implemented
> > > can't be used for a shell command modifying configurations.
> > >
> > > I wrote up a small KIP to fix the issues with the RPC. Please take a
> look
> > > at
> > >
> https://cwiki.apache.org/confluence/display/KAFKA/KIP-339%3A+Create+a+new+ModifyConfigs+API
> > >
> > > best,
> > > Colin
> > >
>
>
>
