Foreach java 8 from list of String to String

Question

I have a member function that will retrieve all membershipId of a member(one member might have multiples of membershipId).After retrieve all membershipId using List,it will call the url like this.

This is my service:

RestRequest request = RestRequest.newBuilder()
                .url("/membership/" + membershipId + "/outlet")
                .get();

This is my controller:

 @RequestMapping(value = "/favouriteStores", method = RequestMethod.GET)
        public Object FavouriteStores(ModelMap modelMap,HttpSession session)throws  Exception {
          String memberId = "5677a7075e3f1b998fc7483b";


 List<Membership> membershipList= memberService.getMembershipByMemberId(memberId);

 List<String>  membershipIds = membershipList.stream().map(m->m.getId()).collect(Collectors.toList());
         String membershipId = membershipIds.toString();

        Set<Outlet> outletSet = membershipService.getOutletByMembershipId(membershipId);

My problem is it will transform the whole membershipId in one url like this "membership/[12345, 54321]/outlet" It should be two url like "membership/[12345]/outlet" and "membership/[54321]/outlet"

I know we can use foreach to do that in controller,but i don't know how.Thanks for any helps.

First URL will be "membership/[12345]/outlet" or "membership/12345/outlet" ? — Mrinal
– Mrinal, Commented Jan 26, 2016 at 9:35

Mrinal · Accepted Answer · 2016-01-26 17:56:52Z

3

Try map method of Stream instead : You can achieve this using map method of Stream.

Set<Outlet> outletSet = membershipIds.stream()
    .map(membershipService::getOutletByMembershipId)
    .collect(Collectors.toSet());

Even you can combine your previous stream operations and omit creation of intermediate list objects :

String memberId = "5677a7075e3f1b998fc7483b";

Set<Outlet> outletSet = memberService.getMembershipByMemberId(memberId)
    .stream()
    .map(Membership::getId)
    .map(membershipService::getOutletByMembershipId)
    .collect(Collectors.toSet())

edited Jan 26, 2016 at 17:56

answered Jan 26, 2016 at 9:41

Mrinal

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2 Comments

Holger Over a year ago

It would be even better, to combine this with the first stream operation to get rid of those intermediate lists which are counteracting the purpose of streams.

Mrinal Over a year ago

Right. I was too focused on the area of question. I have updated my answer.

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