Android : Fast scanning of Files and directories in android

I am creating an application which requires retrieval of selected file present on the device. I know we can use java.io package for retrieval of all files using recursion method. But it seems slow. It takes maximum 10-15 seconds for retrieving of all files. Is there any way to retrieve files besides **recursion ** which can provide Fast Directory scanning.

My second Question is How can we use nio.file class in android. It seems android do not provide support directly

Please help me Thank You