Lambda 對List集合多字段組合去重

public static void main(String[] args) {
        List<QrCodeBaseDTO> saveDTOList = new ArrayList<>();

        QrCodeBaseDTO baseDTO = new QrCodeBaseDTO();
        baseDTO.setAppId("AppId1"); baseDTO.setAppName("AppName1"); baseDTO.setAppType("AppType1"); saveDTOList.add(baseDTO);
        QrCodeBaseDTO baseDTO1 = new QrCodeBaseDTO();
        baseDTO1.setAppId("AppId1"); baseDTO1.setAppName("AppName1"); baseDTO1.setAppType("AppType1"); saveDTOList.add(baseDTO1);
        QrCodeBaseDTO baseDTO2 = new QrCodeBaseDTO();
        baseDTO2.setAppId("AppId"); baseDTO2.setAppName("AppName2"); baseDTO2.setAppType("AppType"); saveDTOList.add(baseDTO2);
        QrCodeBaseDTO baseDTO3 = new QrCodeBaseDTO();
        baseDTO3.setAppId("AppId"); baseDTO3.setAppName("AppName2"); baseDTO3.setAppType("AppType"); saveDTOList.add(baseDTO3);
        QrCodeBaseDTO baseDTO4 = new QrCodeBaseDTO();
        baseDTO4.setAppId("AppId"); baseDTO4.setAppName("AppName4"); baseDTO4.setAppType("AppType"); saveDTOList.add(baseDTO4);
        QrCodeBaseDTO baseDTO5 = new QrCodeBaseDTO();
        baseDTO5.setAppId("AppId"); baseDTO5.setAppName("AppName5"); baseDTO5.setAppType("AppType"); saveDTOList.add(baseDTO5);

        System.out.println("最初多少個:" + saveDTOList.size());
        List<QrCodeBaseDTO> setList = saveDTOList.stream().collect(
                Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(user -> user.getAppId() + ";" + user.getAppName() + ";" + user.getAppType()))), ArrayList::new));
        System.out.println("去重後多少個:" + setList.size());

    }