Flow not updating on SharedPreferences value change

I’m having an issue where after the initial value my Flows aren’t updating when a new value is saved in SharedPreferences.

I’ve linked to a project that reproduces it but the gist is:

       val myPref: Preference<Int> = preferences.getInt(MY_PREF_KEY)

        update_pref.setOnClickListener {
            val selection = (0..2).random()

            GlobalScope.launch { myPref.setAndCommit(selection) }
        }

        myPref.asFlow()
            // This doesn't get triggered after the initial value
            .onEach { Log.d(tag, "PREF CHANGE: $it") }
            .launchIn(GlobalScope)

Simplified project to reproduce.

[davidbilik]

I also had this problem and I’ve traced that it’s connected to the “problem” that my coroutine was probably garbage collected since SharedPreferences does not store strong reference to the registered SharedPreferences.OnSharedPreferenceChangeListener. My code was something like

class MyClass {

    init {
        GlobalScope.launch {
            flowPreferences.getBoolean("my_prop")
                .asFlow()
                .collect {
                    ...
                }
        }
    }
}

I’ve fixed that by storing given Job to the field property

class MyClass {

    val observingJob: Job

    init {
        observingJob = GlobalScope.launch {
            flowPreferences.getBoolean("my_prop")
                .asFlow()
                .collect {
                    ...
                }
        }
    }
}

it’s kind of hack/workaround but it helped

[tfcporciuncula]

Good findings here, but I’m closing this issue as I don’t think this is really related to the library itself.