收集特定条件列表或退出

Question

     if (response.getSubscriber().getGroups() != null) {
         List<SPMGetGroupResponse> groupResponses =  response.getSubscriber().getGroups()
                                .stream()
                                .map(groupId -> callGetGroupAPI(groupId))
                                .filter(r -> r.getResultCode() == CommonResult.SUCCESS.getResultCode())
                                .collect(toList());    

在流中是否有一种方法可以使上述停止r.getResultCode不是SUCCESSFUL？

相当于

的流

List<SPMGetGroupResponse> groupResponses = new ArrayList<>();
    for (String groupId : groupIds) {
        SPMGetGroupResponse grpResponse = callGetGroupAPI(groupId);
        if (grpResponse.getResultCode() == CommonResult.SUCCESS.getResultCode()) {
            groupResponses.add(grpResponse);
        } else {
            break;
        }
     }

Answer 1

Java-8中没有标准方法可以做到这一点。在Java-9中，为此目的添加了名为takeWhile()的新操作：

 List<SPMGetGroupResponse> groupResponses =  response.getSubscriber().getGroups()
                 .stream()
                 .map(groupId -> callGetGroupAPI(groupId))
                 .takeWhile(r -> r.getResultCode() == CommonResult.SUCCESS.getResultCode())
                 .collect(toList());    

某些第三方库，包括我的库StreamEx向后移植takeWhile()：

 List<SPMGetGroupResponse> groupResponses = StreamEx.of(response.getSubscriber().getGroups())
                 .map(groupId -> callGetGroupAPI(groupId))
                 .takeWhile(r -> r.getResultCode() == CommonResult.SUCCESS.getResultCode())
                 .toList();