java 递归查子菜单

 

递归查：

    @Override
    public List<PromotionOrgInfoPO> queryOrgInfo() {
        List<PromotionOrgInfoPO> promotionOrgInfoPOS = pointExchangeDAO.queryOrgInfo();
        List<PromotionOrgInfoPO> rootInfo = new ArrayList<>();
        if (CollectionUtils.isNotEmpty(promotionOrgInfoPOS)) {
            promotionOrgInfoPOS.forEach(promotionOrgInfoPO -> {
                if (Objects.isNull(promotionOrgInfoPO.getParentId())) {
                    rootInfo.add(promotionOrgInfoPO);
                }
            });
            rootInfo.forEach(menu -> {
                List<PromotionOrgInfoPO> childList = getChildMenu(menu.getId(), promotionOrgInfoPOS);
                menu.setChildOrgInfos(childList);
            });
        }
        return rootInfo;
    }

    private List<PromotionOrgInfoPO> getChildMenu(Long id, List<PromotionOrgInfoPO> allMenu) {
        //子菜单
        List<PromotionOrgInfoPO> childList = new ArrayList<>();
        allMenu.forEach(all -> {
            // 遍历所有节点，将所有的父id与传过来的根节点的id比较
            if (all.getParentId().equals(id)) {
                childList.add(all);
            }
        });
        //递归
        childList.forEach(child -> child.setChildOrgInfos(getChildMenu(child.getId(), allMenu)));
        //如果节点下没有子节点，返回一个空List（递归退出）
        if (childList.size() == 0) {
            return new ArrayList<>();
        }
        return childList;
    }

优化：

private List<PromotionOrgInfoPO> getChildMenu(Long id, List<PromotionOrgInfoPO> allMenu) {
    // 构建父节点到子节点的映射
    Map<Long, List<PromotionOrgInfoPO>> childMap = allMenu.stream()
            .collect(Collectors.groupingBy(PromotionOrgInfoPO::getParentId));

    return buildChildMenu(id, childMap);
}

private List<PromotionOrgInfoPO> buildChildMenu(Long id, Map<Long, List<PromotionOrgInfoPO>> childMap) {
    List<PromotionOrgInfoPO> childList = childMap.getOrDefault(id, Collections.emptyList());

    for (PromotionOrgInfoPO child : childList) {
        child.setChildOrgInfos(buildChildMenu(child.getId(), childMap));
    }

    return childList;
}

 

 

常用求和：

Map<String, BigDecimal> currencyCard = paymentVOS.stream().distinct().collect(Collectors.groupingBy(InternalPaymentVO::getDeductCardNo,
                        Collectors.mapping(InternalPaymentVO::getDeductAmount,
                                Collectors.reducing(BigDecimal.ZERO, BigDecimal::add))));

    int points = internalPaymentVOS.stream().filter(v -> v.getType().equals(92)).mapToInt(InternalPaymentVO::getPmUsedPoints).sum();
     
                BigDecimal pointsMoney = internalPaymentVOS.stream().filter(v -> v.getType().equals(92)).map(InternalPaymentVO::getPmUsedMoney).reduce(BigDecimal.ZERO, BigDecimal::add);
                paymentVOS = internalPaymentVOS.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(InternalPaymentVO::getType))), ArrayList::new));