使用java8从2个列表中筛选并获取匹配的记录

Question

我有两个列表，一个是messagePermissionResponseDTOList，另一个是dispatchSMSQList。     我想从dispatchSMSQList中取出被阻止的号码列表。以下是我的工作代码段。     您能指导一下如何转换Lambda表达式或其正确形式吗？ 测试数据的有效链接为https://repl.it/repls/FriendlyImmenseClasses

        TreeSet<Long> blockedNumbersSet = new TreeSet<>();
        for (MessagePermissionResponseDTO permission: messagePermissionResponseDTOList) {
            if (permission.isBlocked()) {
                blockedNumbersSet.add(permission.getPhoneNumber());
            }
        }
        List<DispatchSMSQ> blockedNumbers = dispatchSMSQList.stream().filter(t -> blockedNumbersSet.contains(t.getMdn())).collect(Collectors.toList());

        System.out.print("blockedNumbers-->"+ blockedNumbers.size());

Answer 1

您可以这样做

List<DispatchSMSQ> blockedNumbers = messagePermissionResponseDTOList.stream()
    .filter(MessagePermissionResponseDTO::isBlocked)
    .map(MessagePermissionResponseDTO::getPhoneNumber)
    .collect(Collectors.collectingAndThen(Collectors.toSet(), 
        s -> dispatchSMSQList.stream()
            .filter(d -> s.contains(d.getMdn())).collect(Collectors.toList())));

Answer 2

这应该做到

 messagePermissionResponseDTOList
      .stream()
      .filter(MessagePermissionResponseDTO::isBlocked)
      .map(MessagePermissionResponseDTO::getPhoneNumber)
      .collect(Collectors.toSet())