with this below code i\'m trying to access the file which is stored in asset/raw folder, but getting null and
E/ERR: file:/android
Assets and resources are files on your development machine. They are not files on the device.
For assets, use open() on AssetManager to get an InputStream on your asset.
Also, FWIW:
Uri.parse("file:///android_asset/raw/default_book.txt").toString() is pointless, as it gives you the same string that you started with
file:///android_asset/ only works for WebView