private List<FolderTree> getTreeList(int parentId, List<Folder> folderList) {
    List<FolderTree> treeList = null;
    FolderTree tree = null;
    for (Folder folder : folderList) {
        if((parentId == -1 && folder.getLevel() == 1) || (parentId != -1 && folder.getParentId() == parentId)) {
            tree = new FolderTree(folder.getName());
            tree.setId(folder.getId());
            tree.setFolders(getTreeList(tree.getId(), folderList));
            if(treeList == null) {
                treeList = new ArrayList<FolderTree>();
            }
            treeList.add(tree);
        }
    }
    return treeList;
}