android - Get folders name from Assets directory -

I am trying to get the names of my folders in "property". I can get the names of files with asset manager using assetManager.list (). But the problem is that it does not return only the file names and folders names. So I'm trying to use the listFiles () method but I can not access the asset directory; I have tried the following:

  file dir = new file ("file: /// android_asset /"); File [] files = dir.listFiles ();  

But it does not work :( ... Is there any way to get the names of folders contained in the asset directory?