convert list of objects to Map<String, Object> using map/stream/collect [duplicate]

Question

if I have something like this:

List<Person> fetchedPeople

and I want to stream through it and store it into a key-value map where key is the person ID and value is the object itself (here Person)

private Map<String, Person> people;

I tried something like this but it gives me an error:

PersonCache = people.stream()
      .collect(toMap(Person::getID, Person));

Thanks for your help

after reading the suggested answer, it turned out my question is similar to this question stackoverflow.com/questions/20363719/java-8-listv-into-mapk-v — samjo
– samjo, Commented Mar 30, 2021 at 15:36

CryptoFool · Accepted Answer · 2021-03-30 15:23:07Z

4

I think you want this:

Map<String, Person> result = fetchedPeople.stream().collect(Collectors.toMap(Person::getID, e -> e));

I don't know if there is a way to return "the element itself" without supplying a lambda function that does that, the e -> e part.

answered Mar 30, 2021 at 15:23

CryptoFool

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3 Comments

yeah thanks. This worked!

Super elegant solution! So simple and clean! Thank you