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Making app service work invisible in background

i have an app that runs a background service infinitely while also hiding the app icon and hiding it from the backstack so it wont be visible to the user while running using:
val componentName = ComponentName(this, FullscreenActivity::class.java)
p.setComponentEnabledSetting(
componentName,
PackageManager.COMPONENT_ENABLED_STATE_DISABLED,
PackageManager.DONT_KILL_APP
)
this is how i launch the service from my fragment :
parentFragment?.activity?.startService(
Intent(
requireParentFragment().requireActivity().applicationContext,
RescueService::class.java
).addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
)
which successfully hides the icon and the app from backstack and the service keep running, also when i press the square button on my phone to show the backstack apps running i dont see the app there which is what i want, but if i click the "X" button to clear all backstack apps it also kills my app and my service dies even though the app does not appear there as i mentioned.
Any ideas what makes the service die after doing it? because it did not happen to couple of days ago before i did some changes in my app..
One of the changes i made is turnning my Service into LifecycleService because i needed my service to observe a livedata which needs a LifecycleOwner.Can it be the cause of my service to die when clearing the backstack?
All suggestions will be welcomed !
EDIT1 - here is my TestService that performs voice recording uses WorkManager.I call hideApp() to hide the icon from the phone and make the app invisible from the backstack :
class RecordingWork(
context: Context,
params: WorkerParameters
) : CoroutineWorker(context, params) {
override val coroutineContext = Dispatchers.Main
override suspend fun doWork(): Result {
mSpeechRecognizer.startListening(mSpeechRecognizerIntent)
return Result.success()
}
}
private lateinit var mSpeechRecognizer: SpeechRecognizer
private val mSpeechRecognizerIntent = Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH)
class TestService : Service() {
private lateinit var workManager: WorkManager
override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
Log.d("TestService", "onStartCommand called")
hideApp()
prepareVoiceRecording()
workManager = WorkManager.getInstance(applicationContext)
workManager.enqueue(OneTimeWorkRequestBuilder<RecordingWork>().build())
return START_REDELIVER_INTENT
}
override fun onBind(intent: Intent?): IBinder? {
return null
}
fun prepareVoiceRecording() {
mSpeechRecognizer = SpeechRecognizer.createSpeechRecognizer(applicationContext)
mSpeechRecognizerIntent.putExtra(
RecognizerIntent.EXTRA_LANGUAGE_MODEL,
RecognizerIntent.LANGUAGE_MODEL_FREE_FORM
)
mSpeechRecognizerIntent.putExtra(
RecognizerIntent.EXTRA_LANGUAGE,
Locale.getDefault()
)
mSpeechRecognizer.setRecognitionListener(
object : RecognitionListener {
#RequiresApi(Build.VERSION_CODES.M)
override fun onError(i: Int) {
Log.d(TAG, "onErrorCalled error is $i")
if (i == SpeechRecognizer.ERROR_NETWORK || i == SpeechRecognizer.ERROR_SPEECH_TIMEOUT || i == SpeechRecognizer.ERROR_NO_MATCH) {
Log.d(TAG, "error triggered")
mSpeechRecognizer.destroy()
prepareVoiceRecording()
workManager.enqueue(OneTimeWorkRequestBuilder<RecordingWork>().build())
}
}
#RequiresApi(Build.VERSION_CODES.M)
override fun onResults(bundle: Bundle) {
Log.d(TAG, "onResults Called")
//getting all the matches
val matches = bundle
.getStringArrayList(SpeechRecognizer.RESULTS_RECOGNITION)!!
workManager.enqueue(OneTimeWorkRequestBuilder<RecordingWork>().build())
}
private fun hideApp() {
val componentName = ComponentName(
this,
WelcomeScreenActivity::class.java
)
packageManager.setComponentEnabledSetting(
componentName,
PackageManager.COMPONENT_ENABLED_STATE_DISABLED,
PackageManager.DONT_KILL_APP
)
}
this service does work to repeatedly record voice by rescheduling the Worker every time. but this service also dies when clearing backstack (even though the app does not appear there because of hideApp())

Use workManager for long running background task (some device like Mi phone you need to white list the app for battery saver if you don't do that the OS will kill your app) and hiding of app icon not work in android X (only system apps can hide their icon)

notifyItemChanged() not working when called within setOnUtteranceProgressListener

Edit
I've created a demo project on Github showing the exact problem. Git Project.
I've written an expandable recyclerView in Kotlin Every row has a play button which uses TextToSpeech. The text of the play button should change to stop whilst its playing, then change back to play when it finishes.
When I call notifyItemChanged within onStart and onDone of setOnUtteranceProgressListener, onBindViewHolder is not called and the rows in the recyclerView will no longer expand and collapse correctly.
t1 = TextToSpeech(context, TextToSpeech.OnInitListener { status ->
if (status != TextToSpeech.ERROR) {
t1?.setOnUtteranceProgressListener(object : UtteranceProgressListener() {
override fun onStart(utteranceId: String?) {
recyclerView.adapter.notifyItemChanged(position)
}
override fun onStop(utteranceId: String?, interrupted: Boolean) {
super.onStop(utteranceId, interrupted)
onDone(utteranceId)
}
override fun onDone(utteranceId: String?) {
val temp = position
position = -1
recyclerView.adapter.notifyItemChanged(temp)
}
override fun onError(utteranceId: String?) {}
// override fun onError(utteranceId: String?, errorCode: Int) {
// super.onError(utteranceId, errorCode)
// }
})
}
})
onBindViewHolder:
override fun onBindViewHolder(holder: RabbanaDuasViewHolder, position: Int){
if (Values.playingPos == position) {
holder.cmdPlay.text = context.getString(R.string.stop_icon)
}
else {
holder.cmdPlay.text = context.getString(R.string.play_icon)
}
}
How can I call notifyItemChanged(position) from within setOnUtteranceProgressListener or what callback can I use so that notifyItemChanged only executes when it's safe to execute?

I tried to replicate your issue and I came to know that it is not working because methods of UtteranceProgressListener is not called on main thread and that's why onBindViewHolder method of the adapter is not called.
This worked for me and should work for you too:
Use runOnUiThread{} method to perform actions on RecyclerView like this:
t1.setOnUtteranceProgressListener(object : UtteranceProgressListener() {
override fun onError(utteranceId: String?) {
}
override fun onStart(utteranceId: String?) {
runOnUiThread {
recyclerView.adapter?.notifyItemChanged(position)
}
}
override fun onStop(utteranceId: String?, interrupted: Boolean) {
super.onStop(utteranceId, interrupted)
onDone(utteranceId)
}
override fun onDone(utteranceId: String?) {
val temp = position
position = -1
runOnUiThread {
recyclerView.adapter?.notifyItemChanged(temp)
}
}
}

I solved the problem using runOnUiThread thanks to Birju Vachhani.
For a full working demo of not just the problem I had, but how to correctly expand and collapse rows in a RecyclerView (no onClick events in onBindViewHolder) see my Gitlab Demo Project.

Android Kotlin: How to update recyclerView after async call? getting CalledFromWrongThreadException

I am trying to do an async call and then update a RecyclerView. Much like what's outlined in this question: RecyclerView element update + async network call
However, when I try to do this, I get this error:
android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
Here is my code (the main issue is in the setAlbums function):
class AlbumActivity : AppCompatActivity() {
protected lateinit var adapter: MyRecyclerViewAdapter
protected lateinit var recyclerView: RecyclerView
var animalNames = listOf("nothing")
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_album)
recyclerView = findViewById<RecyclerView>(R.id.rvAnimals)
recyclerView.layoutManager = LinearLayoutManager(this)
adapter = MyRecyclerViewAdapter(this, animalNames)
recyclerView.adapter = adapter
urlCall("https://rss.itunes.apple.com/api/v1/us/apple-music/coming-soon/all/10/explicit.json")
}
private fun urlCall(url: String) {
val client = OkHttpClient()
val request = Request.Builder().url(url).build()
client.newCall(request).enqueue(object : Callback {
override fun onFailure(call: Call, e: IOException) {}
override fun onResponse(call: Call, response: Response) = getJSON(response.body()?.string())
})
}
fun getJSON(data: String?) {
val gson = Gson()
val allAlbums = ArrayList<Album>()
val jsonResponse = JSONObject(data)
val feed = jsonResponse.getJSONObject("feed")
val albums = feed.getJSONArray("results")
for (i in 0 until albums.length()) {
val album = albums.getJSONObject(i)
allAlbums.add(gson.fromJson(album.toString(), Album::class.java))
}
setAlbums(allAlbums)
}
fun setAlbums(albums: ArrayList<*>) {
animalNames = listOf("sue", "betsie")
adapter.notifyDataSetChanged() // This is where I am telling the adapter the data has changed
}
internal inner class Album {
var artistName: String? = null
var name: String? = null
}
}
Does anyone know the issue I am having?

You need to execute your wanted code on your main thread like this :
runOnUiThread(new Runnable() {
#Override
public void run() {
//update your UI
}
});

Your Callback functions will be called on a background thread. In part, that is because OkHttp is not an Android-specific library, so it has no idea about Android's main application thread.
You will need to do something to update the UI in the main application thread. Modern options include:
Have your Callback update a MutableLiveData that your UI observes, as then the UI will get updates on the main application thread
Use existing recipes for using OkHttp with RxJava

Android: MVVM is it possible to display a message (toast/snackbar etc.) from the ViewModel

I want to know what is the best approach to display some sort of message in the view from the ViewModel. My ViewModel is making a POST call and "onResult" I want to pop up a message to the user containing a certain message.
This is my ViewModel:
public class RegisterViewModel extends ViewModel implements Observable {
.
.
.
public void registerUser(PostUserRegDao postUserRegDao) {
repository.executeRegistration(postUserRegDao).enqueue(new Callback<RegistratedUserDTO>() {
#Override
public void onResponse(Call<RegistratedUserDTO> call, Response<RegistratedUserDTO> response) {
RegistratedUserDTO registratedUserDTO = response.body();
/// here I want to set the message and send it to the Activity
if (registratedUserDTO.getRegisterUserResultDTO().getError() != null) {
}
}
});
}
And my Activity:
public class RegisterActivity extends BaseActivity {
#Override
protected int layoutRes() {
return R.layout.activity_register;
}
#Override
protected void onCreate(Bundle savedInstanceState) {
AndroidInjection.inject(this);
super.onCreate(savedInstanceState);
ActivityRegisterBinding binding = DataBindingUtil.setContentView(this, layoutRes());
binding.setViewModel(mRegisterViewModel);
}
What would the best approach be in this case?

We can use a SingleLiveEvent class as a solution. But it is a LiveData that will only send an update once. In my personal experience, using an Event Wrapper class with MutableLiveData is the best solution.
Here is a simple code sample.
Step 1 :
Create an Event class (this is a boilerplate code you can reuse for any android project).
open class Event<out T>(private val content: T) {
var hasBeenHandled = false
private set // Allow external read but not write
/**
* Returns the content and prevents its use again.
*/
fun getContentIfNotHandled(): T? {
return if (hasBeenHandled) {
null
} else {
hasBeenHandled = true
content
}
}
/**
* Returns the content, even if it's already been handled.
*/
fun peekContent(): T = content
}
Step 2 :
At the top of your View Model class, define a MutableLiveData with wrapper (I used a String here, but you can use your required data type), and a corresponding live data for encapsulation.
private val statusMessage = MutableLiveData<Event<String>>()
val message : LiveData<Event<String>>
get() = statusMessage
Step 3 :
You can update the status message within the functions of the ViewModel like this:
statusMessage.value = Event("User Updated Successfully")
Step 4 :
Write code to observe the live data from the View (activity or fragment)
yourViewModel.message.observe(this, Observer {
it.getContentIfNotHandled()?.let {
Toast.makeText(this, it, Toast.LENGTH_LONG).show()
}
})

Display Toast/snackbar message in view (Activity/Fragment) from viewmodel using LiveData.
Step:
Add LiveData into your viewmodel
View just observe LiveData and update view related task
For example:
In Viewmodel:
var status = MutableLiveData<Boolean?>()
//In your network successfull response
status.value = true
In your Activity or fragment:
yourViewModelObject.status.observe(this, Observer { status ->
status?.let {
//Reset status value at first to prevent multitriggering
//and to be available to trigger action again
yourViewModelObject.status.value = null
//Display Toast or snackbar
}
})

How can I randomly reward points for app usage

I am working on an android app where user get points for using the app which can be used to unlock in-app features.
I have a function called rewardPoints() which generates random integer and I want it to get called randomly while the user is using the app. The points then gets added up in database.
fun rewardPoints() {
var points = Random().nextInt((5-1) + 1)
}
How do I call the function rewardPoints() randomly while the user is using/interacting with the app?

I'd use a Handler to post a Runnable that re-posts itself. Like so,
val handler = Handler()
handler.post({
rewardPoints()
handler.postDelayed(this, DELAY_TIME_MS)
})
You could kick this off in your Activity's onResume and stop it onPause to make sure it's only running when the app is active.

You could add an observer on your activities, check whether you have active activities and when that's the case start a periodic task to award points.
Sample:
class MyApp : Application(), Application.ActivityLifecycleCallbacks {
override fun onCreate() {
super.onCreate()
registerActivityLifecycleCallbacks(this)
}
var count: Int by Delegates.observable(0) { _, old, newValue ->
when (newValue) {
0 -> onBackground()
1 -> if (old == 0) onForeground()
}
}
override fun onActivityResumed(activity: Activity?) {
count++
}
override fun onActivityPaused(activity: Activity?) {
count--
}
fun onForeground() {
Log.d("TAG", "start.")
events.start()
}
fun onBackground() {
Log.d("TAG", "stop.")
events.cancel()
}
val events = object: CountDownTimer(Long.MAX_VALUE, 1000) {
// is called once per second as long as your app is in foreground
override fun onTick(millisUntilFinished: Long) {
if (ThreadLocalRandom.current().nextInt(100) < 5) {
Toast.makeText(this#MyApp, "You earned a point.", Toast.LENGTH_SHORT).show()
}
}
override fun onFinish() { /* will never happen */}
}
/* not needed */
override fun onActivityStarted(activity: Activity?) {}
override fun onActivityDestroyed(activity: Activity?) {}
override fun onActivitySaveInstanceState(activity: Activity?, outState: Bundle?) {}
override fun onActivityStopped(activity: Activity?) {}
override fun onActivityCreated(activity: Activity?, savedInstanceState: Bundle?) {}
}
If you use architecture components Lifecycle, implementing above is even simpler with https://developer.android.com/reference/android/arch/lifecycle/ProcessLifecycleOwner and listening to the desired Lifecycle.Event