Java 8清单清单

Question

I have one question regarding Java8 stream api. I have one class as below

class MyDetails(
    val fname:String,
    val lname:String,
    val myAccountList:List<Myaccount>
)

class Myaccount(
    val accID:String,
    val accType:String,
    val associateList:List<Associate>
)

class Associate(
    val associateID:String,
    val role:String
)

Now I want to get

List of Myaccount

whose role is " owner "(Let us suppose).

For that i wrote below code but its not working

myDetailsObject?.myAccountList?.stream()?.filter { account ->
            account?.associateList?.stream()?.allMatch{associate ->
                println("Value of Role ${associate.role}")
                "owner".equals(associate.role)}!!
        }?.collect(Collectors.toList())?.toList()

Output for Print statement is-

Value of Role owner
Value of Role view
Value of Role read
Value of Role owner
Value of Role write
Value of Role write
Value of Role view

If owner is available in list why i am getting list of size zero? But above code is not working for me..Any suggestion would be appreciated. Even though code syntax is in Kotlin but Java code would also be helpful.

Answer 1

Why not simply use kotlin for the job?

fun wanted(candidates: List<Myaccount>) =
    candidates.filter { it.associateList.any { it.role == "wanted" } }

Answer 2

By asking for 'allMatch', you expect all the elements to have 'owner'. use anyMatch() instead?

myDetailsObject?.myAccountList?.stream()?.filter { account ->
            account?.associateList?.stream()?.anyMatch{associate ->
                println("Value of Role ${associate.role}")
                "owner".equals(associate.role)}!!
        }?.collect(Collectors.toList())?.toList()

Answer 3

The Java code to filter the accounts objects whose all the associates are owner and collect as list is

myAccountList.stream()
    .filter(account -> account.associateList.stream()
               .allMatch(associate -> "owner".equals(associate.role))
     .collect(Collectors.toList())

EDIT: (based on OP update)

If you want to pick an account if at least one of the associates' role is owner, then you have to use anyMatch in place of allMatch