internal-storage

Files are saved on device's internal storage

By default, the saved files are private to the application

• Other apps cannot access the files
• User is also not allowed to access the files

When the app is uninstalled

• The saved files related to the app are also removed from device

Important Methods

• openFileOutput(fileName: String, mode: Int) it creates a new file if the file does not exist

  • int mode
    • MODE_PRIVATE (default) makes the file private to the application
    • MODE_APPEND if the file already exists then it writes the data at the end of the file

• write(dataBytes: byte[]) write the data in the form of bytes to a file

• close() close the FileOutputStream

also internal cache storage is same

• to access cache file, need to use getCacheDir() method
• Limited for 1 MB

external-storage

Files are saved on device's external storage such as SD Card

The saved files can be private or public

• getExternalFileDir()

  • Private Files, deleted when the app is uninstalled
  • Files belong to your own app but technically user and other apps have access to it

• getExternalStoragePublicDirectory()

  • Public Files, not deleted on uninstallation of the app
  • Files can be used by your app, other apps and the user.

Not always available for use

• if user removes the SD Card the files become inaccessible
• if SD Card is mounted as USD storage the files are out of reach

Always check for its availability before using external storage

• to access cache file, need to use getExternalCacheDir() method