CODEWITHSUNDEEP
javajava-stream
Denys Bondarenko
Denys Bondarenko

Reputation: 183

Stream collect to collection with diamonds

How can I collect stream to collection with diamonds?

For example, previously I had code like this for singleton list, but for now I can have more than one element.

private static final GrantedAuthority userAuthority = new SimpleGrantedAuthority("ROLE_USER");
private static final Collection<? extends GrantedAuthority> defaultUserAuthorities =
        Collections.singletonList(userAuthority);

And I trying to do like this, but stuck with Collectors.

Collection<? extends GrantedAuthority> collect = user.getRoles().stream()
                .map(r -> r.getName().name())
                .map(SimpleGrantedAuthority::new)
                .collect(Collectors.toCollection(/*What should be here?*/));

How can I collect to this Collection<? extends GrantedAuthority> ?

Upvotes: 0

Views: 77

Answers (2)

WJS
WJS

Reputation: 40072

You can also just use a List<? extends GrantedAuthority> as List extends Collection.

List<? extends GrantedAuthority> list = user.getRoles().stream()
                .map(r -> r.getName().name())
                .map(SimpleGrantedAuthority::new)
                .toList();

Note that Collection does not have the get and add methods that are provided by List, assuming you want to retrieve and/or set the values.

Upvotes: 2

Unmitigated
Unmitigated

Reputation: 89404

.collect(Collectors.toList()) can be used, as a List is a Collection.

Upvotes: 2

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