Android “remembers” shared preferences after complete app uninstall

Question

In my Android app I use a set of randomly generated file names to store some data. In order to ensure that the same set of file names are generated at app restart - and are

Answer 1

Based on @hungryghost's suggestion the I eventually implemented a solution

Problem:Shared preferences can be remembered by Android after app reinstall and blanket instructions in the manifest along the lines of android:allowBackup = "false" are not a solution.

So why not turn the problem into a solution on its own? Here is what I do

• Check shared preferences for a build specific key.

• If that key is not found I do two things

  1. Clear out all shared preferences, context.deleteSharedPrefernces(filename)
  2. Now create that build specific key
  3. When I make app changes that require old preferences to be forgotten I simply change the build specific key.

Answer 2

On (re)install, your app may be restoring files from Google auto-backup (via Google Drive). To disable this feature, you can explicitly set it to false in the manifest:

<manifest ... >
    ...
    <application android:allowBackup="false" ... >
        ...
    </application>
</manifest>

If you'd like more granular control over what is backed up/restored and what is not, you can include or exclude specific files from the backups.

See auto backup documentation: https://developer.android.com/guide/topics/data/autobackup#EnablingAutoBackup

If you don't want to disable auto backups, but want to reinstall with a "clean slate" (for testing purposes), you can do one of the following:

• Clear app data after reinstall. This will wipe out files that were restored automatically on install
• Clear app data prior to uninstall, then force a new backup (so old one gets reset) by using this command: adb shell bmgr backupnow <PACKAGE>

See how to test backups documentation: https://developer.android.com/guide/topics/data/testingbackup#TestingBackup

Answer 3

to extend on this, for example mobile/src/debug/AndroidManifest.xml

<application
    tools:replace="android:allowBackup"
    android:allowBackup="false">

    ...

</application>

alike this one can disable auto-backup for debug builds - but keep it enabled for release builds.

simply because disabling auto-backup for release builds might not be the intended outcome.