Android fails to create files or folders

1. Check whether read and write permissions have been applied for in AndroidManifest.xml, and check whether read and write permissions have been dynamically applied for Android 6.0 or higher.

2 , add a line in AndroidManifest.xml:

android:requestLegacyExternalStorage="true"

3. To create a single file or folder use:

file.mkdir();

To create a multi-level folder, be sure to use:

file.mkdirs();