CODEWITHSUNDEEP
javajava-8java-stream
user3369592
user3369592

Reputation: 1447

Get a list of attributes wtih converted type from object list java 8

I know how to get a list of attributes from an object list into a new list. But how about if I also want to convert the type from int to long. For example, if I have a user class with a method called get userId (which is int type) and myUserList is a list of user objects. 

List<Integer> userIdList = myUserList.stream()
  .map(User::getUserId)
  .collect(Collectors.toList());

So I could get a list of userId with int type. How about if I want to convert int to long. I tried this code: 

 myUserList.stream()
  .map(Long::intValue(User::getUserId))
  .collect(Collectors.toList());

I had an error can not resolve method static.... May anyone tell me how to fix it?

Upvotes: 1

Views: 103

Answers (1)

khelwood
khelwood

Reputation: 59212

You can convert an int to a long by casting

.map(user -> (long) user.getUserId())

or (since it needs to be boxed anyway to go into a list), you can use Long.valueOf. 

userList.stream()
        .map(user -> Long.valueOf(user.getUserId()))
        .collect(Collectors.toList());

Upvotes: 4

Related Questions