primitive array to map using a stream api java 8

Question

I need to create a map from primitive array of integers where key is index and value is element by current index. How can i do it using a Java Stream API?

I'm trying to do something like this but it doesn't work out for me.

        IntStream.range(0, nums.length)
                .collect(Collectors.toMap(i -> i, i -> nums[i]));

It’s must faster to look at Javadoc instead of waiting for help from strangers. — Abhijit Sarkar, Jul 25 '21 at 08:54
Could you explain ["but it doesn't work"](https://web.archive.org/web/20180124130721/http://importblogkit.com/2015/07/does-not-work/)? — Pshemo, Jul 25 '21 at 08:54

score 2 · Accepted Answer · answered Jul 25 '21 at 08:52

2

IntStream doesn't have the collect() method you are trying to use, so you have to convert your IntStream to a Stream<Integer>:

Map<Integer,Integer> map =
    IntStream.range(0, nums.length)
             .boxed()
             .collect(Collectors.toMap(Function.identity(), i -> nums[i]));

answered Jul 25 '21 at 08:52

Eran

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the same answer is mentioned here: https://stackoverflow.com/a/57638246/8359623 why do you give a repeated answer when you could ping the link as well. – Papai from BEKOAIL Jul 25 '21 at 09:05
@PapaifromBEKOAIL - I disagree with you. OP's problem is not about how to do it; rather, it's about why his code is not working. – Arvind Kumar Avinash Jul 25 '21 at 16:25

primitive array to map using a stream api java 8

1 Answers1