Enum enhancement

[Giguere, Thierry]

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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