java 8 遞歸 並且根據某個字段排序

1.實體bean結構

public class DmpDictVo {
    @ApiModelProperty(value = "數據id")
    private String id;

    @ApiModelProperty(value = "父id")
    private String pid;

    @ApiModelProperty(value = "描述")
    private String name;

　　//初始化 children 避免報空指針異常

    List<DmpDictVo> children = new ArrayList<>();
}

// 根據自己的業務編寫
private List<DmpDictVo> searchFatherDmpDict() {
　// 查詢出所有的數據字典

List<QaCategoryVo> qaCategoryVoList = findAll(type);
// 遞歸封裝數據

return makeTree(qaCategoryVoList, -1L);

}


/**
 * 遞歸方法構造
 */

private List<QaCategoryVo> makeTree(List<QaCategoryVo> departmentList, Long pId) {

    //子類
    List<QaCategoryVo> children = departmentList.stream().filter(x -> x.getPid().equals(pId)).collect(Collectors.toList());
    // 排序
    children = children.stream().sorted(Comparator.comparing(QaCategoryVo::getSort, Comparator.nullsLast(Integer::compareTo)).reversed()).collect(Collectors.toList());
　　
    if(children.isEmpty()){
        return null;
    }
    //后輩中的非子類
    List<QaCategoryVo> successor = departmentList.stream().filter(x -> !x.getPid().equals(pId)).collect(Collectors.toList());

    for (QaCategoryVo x : children) {
        List<QaCategoryVo> qaCategoryVos = makeTree(successor, x.getId());
        x.setChildren(qaCategoryVos);
    }
    return children;

}