CODEWITHSUNDEEP
androidkotlinsharedpreferences
th3ant
th3ant

Reputation: 338

onSharedPreferenceChanged() not fired when observing from separate processes

I have an application that consists of two separate processes; the main application and a background service that has a separate process defined with android:process=":process_name" in the manifest.

When using SharedPreferences I observe that I can store and load values on one process, and retrieve them on the other process completely fine.

Main Activity:

override fun onStart() {
    // ...
    val prefs = getSharedPreferences(PREFERENCES_ID, Context.MODE_PRIVATE)
    val editor = prefs.edit()
    editor.putInt("TEST", 42)
    editor.commit()
}

Service:

override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
    // ...
    val prefs = getSharedPreferences(PREFERENCES_ID, Context.MODE_PRIVATE)
    val retrieved = prefs.getInt("TEST", -1)
    Log.d("Service", "Retrieved $retrieved") // prints "Retrieved 42"
}

However, when registering a OnSharedPreferenceChangeListener to observe these changes on both the activity and service, I only recieve the changes my SharedPreferences instance on the process that the change was made on. (This also happens when creating the shared preferences instance with the Activity/Service's applicationContext.)

I also note that this behaviour does not occur when removing the android:process directive in the manifest, which leads me to believe the different processes cause this behaviour.

  1. Is there some difference in how changes are broadcast to the listeners across different processes?
  2. Is it possible to observe these changes across processes?

(I acknowledge I could move my application to be a single process or implement a "changed" message of some sort through some other IPC such as a Messenger every time my code makes a change to the SharedPreferences, however these are not attractive options for this application.)

Upvotes: 1

Views: 103

Answers (0)

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