树结构生成示例模板2种

方式一：

 public List<DevCategory> list() {
    List<DevCategory> allList = devCategoryDao.findAllData();
      return allList.stream().filter(s -> s.getPid() == null || s.getPid().isBlank()).peek(item ->
          findChildren(item, allList)).toList();
 }

private void findChildren(DevCategory devCategory, List<DevCategory> allList) {
    List<DevCategory> child = new ArrayList<>();
    allList.forEach(s -> {
        if (Objects.equals(String.valueOf(devCategory.getId()), s.getPid())) {
            child.add(s);
            findChildren(s, allList);
        }
        devCategory.setChildren(child);
    });
}

方式二：

List<DevCategory> allList = devCategoryDao.findAllData();
return allList.stream().filter(s -> s.getPid() == null || s.getPid().isBlank())
        .peek(item -> item.setChildren(findChildren(item.getId(), allList))).collect(Collectors.toList());

private List<DevCategory> findChildren(Long id, List<DevCategory> allList) {
    return allList.stream().filter(s -> {
        return Objects.equals(String.valueOf(id), s.getPid());
    }).peek(item -> item.setChildren(findChildren(item.getId(), allList))).collect(Collectors.toList());
}