Every Android-compatible device supports shared external storage. This storage may be removable (such as an SD card) or internal (non-removable). Files saved to external storage are world-readable. The user can modify them when USB mass storage is enabled. You can use the following code snippets to persistently store sensitive information to external storage as the contents of the file password.txt.
The file will be created and the data will be stored in a clear text file in external storage once the activity has been called.
It's also worth knowing that files stored outside the application folder (data/data/<package-name>/) will not be deleted when the user uninstalls the application. Finally, it's worth noting that the external storage can be used by an attacker to allow for arbitrary control of the application in some cases.