Java 8 stream: convert comma separated string to the list of abstract Enum

Question

Is it possible to convert a comma separated string to the list of java.lang.Enum by using stream?

My original code is the following, which is working:

List<String> inValuesStr = Arrays.asList(criteria.getValue().toString().split(","));
List<Enum> inValues = new ArrayList<>();
for (String val : inValuesStr){
    inValues.add(Enum.valueOf(path.getType(),val));
}

I tried to refactor it to be as code below:

List<Enum> inValues = Arrays.stream(criteria.getValue().toString().split(","))
    .map(v -> Enum.valueOf(path.getType(),v))
    .collect(Collectors.toList());

Looks very basic... but, the following compile-time error is shown:

Error:(--, --) java: incompatible types: java.lang.Object cannot be converted to java.util.List<java.lang.Enum>

I can't understand where is the mistake. Did someone had the same experience? Thanks for sharing a solution.

It works alright for me too, but I don't use the same valueOf definition with two parameters — Yassin Hajaj
– Yassin Hajaj, Commented Jul 16, 2019 at 13:27
@Arnaud Claudel. It can be any enum type. For example, I have a Person entity which has a field sex, which is Sex enum. So this code is inside of an generic function that should convert list of string values criteria.getValue() to the list of specific type of enum path.getType(). What is interesting is that if I remove abstraction, it works List<Sex> inValues = Arrays.stream(criteria.getValue().toString().split(",")) .map(v -> Sex.valueOf(v)) .collect(Collectors.toList()); But, I would like to keep it abstract — andriy
– andriy, Commented Jul 16, 2019 at 13:40
show your entire code that we can re-produce, not long comments; voting to close for now. — Eugene
– Eugene, Commented Jul 16, 2019 at 13:42

OldCurmudgeon · Accepted Answer · 2019-07-16 13:25:33Z

0

This works fine for me:

enum Ascii {
    A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z;
}

private void test() throws InterruptedException {
    List<String> inValuesStr = Arrays.asList("A,B,C,D,E,F,G,H,I,J,K,L,M,N".split(","));
    List<Ascii> list = inValuesStr.stream()
        .map(s -> Ascii.valueOf(s))
        .collect(Collectors.toList());
}

answered Jul 16, 2019 at 13:25

OldCurmudgeon

66k18 gold badges126 silver badges220 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Yassin Hajaj Over a year ago

He uses path.getType() as first parameter of Enum::valueOf. This doesn't answer the question at all

tobias_k Over a year ago

@YassinHajaj Works just the same with Enum.valueOf(Ascii.class, s)

BeUndead Over a year ago

I suspect the problem here is that path.getType() returns Class<?>, not Class<? extends Enum>. Using path.getType().asSubclass(Enum.class) (and potentially casting the result of the Enum.valueOf call...) should get around this.

Holger Over a year ago

@user2478398 not with Class<?>, but with the raw type Class. But in that case, asSubclass won’t help as the result of a generic operation on a raw type will be again a raw type.

Collectives™ on Stack Overflow

Java 8 stream: convert comma separated string to the list of abstract Enum

1 Answer 1

4 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related