Enum enhancement

[Federico Peralta Schaffner]

I really like Tagir's suggestion about (2): Optional<E> findValue(String
name)

But this leads me to a question regarding Map... Have you ever considered
adding the equivalent default method to the Map interface? It might be
something like this:

default Optional<V> find(Object key) {
    return Optional.ofNullable(this.get(key));
}

Or maybe not allowing null as a key:

default Optional<V> find(Object key) {
    return Optional.ofNullable(this.get(Objects.requireNonNull(key)));
}

Of course, this might become ambiguous if the map supports null values, but
we have containsKey for that...

Regards,
fps.-


El vie., 7 dic. 2018 a las 11:38, Tagir Valeev (<amaembo at gmail.com>)
escribió:

> As for (2) probably Optional<E> findValue(String name) would be better, as
> you may decide what to do if it's absent using all the optional API.
>
> With best regards,
> Tagir Valeev.
>
> пт, 7 дек. 2018 г., 21:28 Brian Goetz brian.goetz at oracle.com:
>
> > (1) is already tracked as
> >
> >      https://bugs.openjdk.java.net/browse/JDK-8073381
> >
> > It is not as "easy" as you think in that these enum methods are
> > generated by the compiler, not as ordinary library code, but it's not
> > prohibited.
> >
> > (2) is not unreasonable.  As there's no language component to it, you
> > could take this directly to corelibs-dev for further evaluation.
> >
> > On 12/7/2018 9:13 AM, Giguere, Thierry wrote:
> > > Hello,
> > >
> > > Related to the follow link and JEP 301<
> https://openjdk.java.net/jeps/301>
> > :
> > >
> > >
> >
> http://mail.openjdk.java.net/pipermail/amber-spec-experts/2018-December/000876.html
> > >
> > > What is also missing and long-time due for enum right now and could be
> > added quickly is more methods:
> > >
> > > 1) We need to be able to iterate efficiently on enum. Currently calling
> > method T[] values() duplicate the internal array. Moreover you need to go
> > through method Arrays.stream() to convert the newly created array to
> > stream. Adding a stream() method and a forEach() method would help fix
> this
> > problem. Optionally a iterator() method could be provided
> > >
> > >        Arrays.stream(MyEnum.values()).forEach();
> > >
> > > could be replaced by something like :
> > >
> > >        MyEnum.forEach();
> > >
> > > And
> > >
> > >        Arrays.stream(MyEnum.values()).map(...
> > >
> > > could be written :
> > >
> > >        MyEnum.stream().map(...
> > >
> > > 2) T valueOfOrDefault : pretty much like getOrDefault of the map
> > interface. This method don't throw exception and fallback on default
> value.
> > That would ease use of enum in stream / lambda programming
> > >
> > >              @Nonnull
> > >              MyEnum myEnum = MyEnum.DEFAULT_VALUE;
> > >
> > >              try {
> > >                    myEnum = MyEnum.valueOf(...);
> > >              } catch (NullPointerException | IllegalArgumentException
> e)
> > {
> > >                    // Just keep going with on the default value
> > >              }
> > >
> > > Since exception are thrown it doesn't fit very well in stream / lambda
> > usage. Something like this :
> > >
> > > MyData.stream().map(MyEnum::valueOf).forEach()
> > >
> > > Must be converted to :
> > >
> > >                  MyData.stream().map(d -> {
> > >                                 try {
> > >                                                  return
> > MyEnum.valueOf(...);
> > >                                 } catch (Exception e) {
> > >                                                  return
> > MyEnum.DEFAULT_VALUE;
> > >                                                }
> > >                  }).forEach();
> > >
> > > It would be great to write at least something like :
> > >
> > >                  MyData.stream().map(d -> MyEnum.valueOfOrDefault(d,
> > MyEnum.DEFAULT_VALUE)).forEach();
> > >
> > > My feeling is these enhancement could be easily and quickly added
> > >
> > > Thierry Giguère
> > >
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