Kotlin中对象排序（和Java的区别）

java中对一个查询出来的List进行 排序

  /**
     *
     * @param catalog
     * @param treeList
     */
    private void addToTreeList(CatalogVo catalog, ArrayList<CatalogVo> treeList) {
        treeList.add(catalog);
        if (catalog.getChild().size() > 0) {
            catalog.getChild().sort((CatalogVo c1, CatalogVo c2) -> c1.getOrder().compareTo(c2.getOrder()));
            for (CatalogVo cv : catalog.getChild()) {
                addToTreeList(cv, treeList);
            }
        } else {
            return;
        }
    }

kotlin中对一个list进行排序，就是这么粗暴，直接it.对象属性，就可以根据对象的属性进行排序。it是kotlin自带关键字

 /**
     *
     * @param catalog
     * @param treeList
     */
    private fun addToTreeList(catalog: CatalogVo, treeList: ArrayList<CatalogVo>) {
        treeList.add(catalog)

        val childList = catalog.child!!

        if (childList.size > 0) {
            childList.sortBy { it.order }
            for (cv in childList) {
                addToTreeList(cv, treeList)
            }
        } else {
            return
        }
    }