java递归方法示例

 
@Override
public list getCateGoryTree() {

List categoryEntities = baseDao.selectList(null);

    List<CategoryEntity> collect = categoryEntities.stream().filter(entity ->
            entity.getParentCid() == 0  // 获取父类
    ).map(menu->{ // 映射子类
         menu.setChild(getChildMenu(menu,categoryEntities)); // 调用递归方法子类
         return menu;
    }).sorted((m1,m2)->{
        return ( m1.getSort()==null?0:m1.getSort())-(m2.getSort()==null?0:m2.getSort());
    }).collect(Collectors.toList());
    return collect;
}


//递归子类
private List<CategoryEntity> getChildMenu(CategoryEntity root,List<CategoryEntity> all){
    List<CategoryEntity> collect = all.stream().filter(entity -> {
        return entity.getParentCid() == root.getCatId();
    }).map(entity->{
        entity.setChild(getChildMenu(entity,all)); // 递归获取层级子类
        return entity;
    }).sorted((m1,m2)->{
        return (m1.getSort()==null?0:m1.getSort())-(m2.getSort()==null?0:m2.getSort());
    }).collect(Collectors.toList());
    return collect;
}