Related
I'm newbie use Kotlin on my dev apps android,
and now, I on step learn to implement Update UI with LiveData, Retrofit, Coroutine on Recyclerview. The My Apps:
MainActivity > MainFragment with 3 Tab fragment > HomeFragment, DashboardFragment, and SettingsFragment
I call function to get data from server on onCreateView HomeFragment, and observe this with show shimmer data on my Recylerview when is loading, try update RecyclerView when success, and show view Failed Load -button refresh when error.
The problem is:
Adapter Recyclerview not Update when success get Data from Server. Adapter still show shimmer data
With case error (no Internet), i show view Failed Load, with button refresh. Tap to refresh, i re-call function to get data server, but fuction not work correct. Recyclerview show last data, not show Failed Load again.
Bellow my code
HomeFragment
private var _binding: FragmentHomeBinding? = null
private val binding get() = _binding!!
private lateinit var adapterNews: NewsAdapter
private var shimmerNews: Boolean = false
private var itemsDataNews = ArrayList<NewsModel>()
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View {
// Inflate the layout for this fragment
_binding = FragmentHomeBinding.inflate(inflater, container, false)
......
newsViewModel = ViewModelProvider(requireActivity()).get(NewsViewModel::class.java)
//news
binding.frameNews.rvNews.setHasFixedSize(true)
binding.frameNews.rvNews.layoutManager = llmh
adapterNews = NewsAdapter(itemsDataNews, shimmerNews)
binding.frameNews.rvNews.adapter = adapterNews
// Observe
//get News
newsViewModel.refresh()
newsViewModel.newsList.observe(
viewLifecycleOwner,
androidx.lifecycle.Observer { newsList ->
newsList?.let {
binding.frameNews.rvNews.visibility = View.VISIBLE
binding.frameNews.rvNews.isNestedScrollingEnabled = true
binding.frameNews.itemNewsLayoutFailed.visibility = View.GONE
if (it.size == 0)
binding.frameNews.root.visibility = View.GONE
else
getDataNews(it)
}
})
newsViewModel.loading.observe(viewLifecycleOwner) { isLoading ->
isLoading?.let {
binding.frameNews.rvNews.visibility = View.VISIBLE
binding.frameNews.rvNews.isNestedScrollingEnabled = false
binding.frameNews.itemNewsLayoutFailed.visibility = View.GONE
getDataNewsShimmer()
}
}
newsViewModel.loadError.observe(viewLifecycleOwner) { isError ->
isError?.let {
binding.frameNews.rvNews.visibility = View.INVISIBLE
binding.frameNews.itemNewsLayoutFailed.visibility = View.VISIBLE
binding.frameNews.btnNewsFailed.setOnClickListener {
newsViewModel.refresh()
}
}
}
....
return binding.root
}
#SuppressLint("NotifyDataSetChanged")
private fun getDataNewsShimmer() {
shimmerNews = true
itemsDataNews.clear()
itemsDataNews.addAll(NewsData.itemsShimmer)
adapterNews.notifyDataSetChanged()
}
#SuppressLint("NotifyDataSetChanged")
private fun getDataNews(list: List<NewsModel>) {
Toast.makeText(requireContext(), list.size.toString(), Toast.LENGTH_SHORT).show()
shimmerNews = false
itemsDataNews.clear()
itemsDataNews.addAll(list)
adapterNews.notifyDataSetChanged()
}
override fun onDestroyView() {
super.onDestroyView()
_binding=null
}
NewsViewModel
class NewsViewModel: ViewModel() {
val newsService = KopraMobileService().getNewsApi()
var job: Job? = null
val exceptionHandler = CoroutineExceptionHandler { _, throwable ->
onError("Exception handled: ${throwable.localizedMessage}")
}
val newsList = MutableLiveData<List<NewsModel>>()
val loadError = MutableLiveData<String?>()
val loading = MutableLiveData<Boolean>()
fun refresh() {
fetchNews()
}
private fun fetchNews() {
loading.postValue(true)
job = CoroutineScope(Dispatchers.IO + exceptionHandler).launch {
val response = newsService.getNewsList()
withContext(Dispatchers.Main) {
if (response.isSuccessful) {
newsList.postValue(response.body()?.data)
loadError.postValue(null)
loading.postValue(false)
} else {
onError("Error : ${response.message()} ")
}
}
}
loadError.postValue("")
loading.postValue( false)
}
private fun onError(message: String) {
loadError.postValue(message)
loading.postValue( false)
}
override fun onCleared() {
super.onCleared()
job?.cancel()
}
}
NewsAdapter
NewsAdapter(
var itemsCells: List<NewsModel?> = emptyList(),
var shimmer: Boolean ,
) :
RecyclerView.Adapter<ViewHolder>() {
private lateinit var context: Context
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): NewsHomeViewHolder {
context = parent.context
return NewsHomeViewHolder(
NewsItemHomeBinding.inflate(LayoutInflater.from(parent.context), parent, false)
)
}
override fun onBindViewHolder(holder: NewsHomeViewHolder, position: Int) {
holder.bind(itemsCells[position]!!)
}
inner class NewsHomeViewHolder(private val binding: NewsItemHomeBinding) :
ViewHolder(binding.root) {
fun bind(newsItem: NewsModel) {
binding.newsItemFlat.newsTitle.text = newsItem.name
binding.newsItemFlatShimmer.newsTitle.text = newsItem.name
binding.newsItemFlat.newsSummary.text = newsItem.name
binding.newsItemFlatShimmer.newsSummary.text = newsItem.name
if (shimmer) {
binding.layoutNewsItemFlat.visibility = View.INVISIBLE
binding.layoutNewsItemFlatShimmer.visibility = View.VISIBLE
binding.layoutNewsItemFlatShimmer.startShimmer()
} else {
binding.layoutNewsItemFlat.visibility = View.VISIBLE
binding.layoutNewsItemFlatShimmer.visibility = View.INVISIBLE
}
}
}
override fun getItemCount(): Int {
return itemsCells.size
}
I hope someone can help me to solve the problem. thanks, sorry for my English.
You have 3 different LiveDatas, right? One with a list of news data, one with a loading error message, and one with a loading state.
You set up an Observer for each of these, and that observer function gets called whenever the LiveData's value updates. That's important, because here's what happens when your request succeeds, and you get some new data:
if (response.isSuccessful) {
newsList.postValue(response.body()?.data)
loadError.postValue(null)
loading.postValue(false)
}
which means newsList updates, then loadError updates, then loading updates.
So your observer functions for each of those LiveDatas run, in that order. But you're not testing the new values (except for null checks), so the code in each one always runs when the value updates. So when your response is successful, this happens:
newsList observer runs, displays as successful, calls getDataNews
loadError observer runs, value is null so nothing happens
loading observer runs, value is false but isn't checked, displays as loading, calls getDataNewsShimmer
So even when the response is successful, the last thing you do is display the loading state
You need to check the state (like loading) before you try to display it. But if you check that loading is true, you'll have a bug in fetchNews - that sets loading = true, starts a coroutine that finishes later, and then immediately sets loading = false.
I'd recommend trying to create a class that represents different states, with a single LiveData that represents the current state. Something like this:
// a class representing the different states, and any data they need
sealed class State {
object Loading : State()
data class Success(val newsList: List<NewsModel>?) : State()
data class Error(val message: String) : State()
}
// this is just a way to keep the mutable LiveData private, so it can't be updated
private val _state = MutableLiveData<State>()
val state: LiveData<State> get() = _state
private fun fetchNews() {
// initial state is Loading, until we get a response
_state.value = State.Loading
job = CoroutineScope(Dispatchers.IO + exceptionHandler).launch {
val response = newsService.getNewsList()
// if you're using postValue I don't think you need to switch to Dispatchers.Main?
_state.postValue(
// when you get a response, the state is now either Success or Error
if (response.isSuccessful) State.Success(response.body()?.data)
else State.Error("Error : ${response.message()} ")
)
}
}
And then you just need to observe that state:
// you don't need to create an Observer object, you can use a lambda!
newsViewModel.state.observe(viewLifecycleOwner) { state ->
// Handle the different possible states, and display the current one
// this lets us avoid repeating 'binding.frameNews' before everything
with(binding.frameNews) {
// You could use a when block, and describe each state explicitly,
// like your current setup:
when(state) {
// just checking equality because Loading is a -singleton object instance-
State.Loading -> {
rvNews.visibility = View.VISIBLE
rvNews.isNestedScrollingEnabled = false
itemNewsLayoutFailed.visibility = View.GONE
getDataNewsShimmer()
}
// Error and Success are both -classes- so we need to check their type with 'is'
is State.Error -> {
rvNews.visibility = View.INVISIBLE
itemNewsLayoutFailed.visibility = View.VISIBLE
btnNewsFailed.setOnClickListener {
newsViewModel.refresh()
}
}
is State.Success -> {
rvNews.visibility = View.VISIBLE
rvNews.isNestedScrollingEnabled = true
itemNewsLayoutFailed.visibility = View.GONE
// Because we know state is a Success, we can access newsList on it
// newsList can be null - I don't know how you want to handle that,
// I'm just treating it as defaulting to size == 0
// (make sure you make this visible when necessary too)
if (state.newsList?.size ?: 0 == 0) root.visibility = View.GONE
else getDataNews(state.newsList)
}
}
// or, if you like, you could do this kind of thing instead:
itemNewsLayoutFailed.visibility = if (state is Error) VISIBLE else GONE
}
}
You also might want to break that display code out into separate functions (like showError(), showList(state.newsList) etc) and call those from the branches of the when, if that makes it more readable
I hope that makes sense! When you have a single value representing a state, it's a lot easier to work with - set the current state as things change, and make your observer handle each possible UI state by updating the display. When it's Loading, make it look like this. When there's an Error, make it look like this
That should help avoid bugs where you update multiple times for multiple things, trying to coordinate everything. I'm not sure why you're seeing that problem when you reload after an error, but doing this might help fix it (or make it easier to see what's causing it)
this is my viewModel code:
val workout = state.get<Workout>("workout")
var steps : List<Step> = emptyList()
fun getSteps() = viewModelScope.launch {
steps = workout?.let { stepDao.getWorkoutSteps(it.workoutId) }!!
Log.e("KEK", steps.size.toString())
}
and the fragment:
viewModel.getSteps()
if (viewModel.steps.isNotEmpty()) {
binding.apply {
currentStepName.text = viewModel.steps[0].name
currentStepDuration.text = viewModel.steps[0].length.toString()
nextStep.text = "${viewModel.steps[1].name} : ${viewModel.steps[1].length.toString()}"
}
}
this part where i fill the nextStep text doesn't work, a second item in the list exists, but the text doesn't get shown `
thank you
When you call viewModel.getSteps() it starts a coroutine, so you need to wait for it to finish. but you don't wait and try to update the UI using viewModel.steps which may not have been updated yet, because coroutine may not have started.
in your case you can use a LiveData object to fix the issue.
In your ViewModel
val liveSteps: MutableLiveData<List<Step>> = MutableLiveData()
fun getSteps() = viewModelScope.launch {
steps = workout?.let { stepDao.getWorkoutSteps(it.workoutId) }!!
liveSteps.postValue(steps)
Log.e("KEK", steps.size.toString())
}
Now observe this LiveData in Fragment and update UI
viewModel.liveSteps.observe(viewLifeCycleOwner, androidx.lifecycle.observe{
if(!(it.isNullOrEmpty()) && it.size == 2){
binding.apply {
currentStepName.text = it[0].name
currentStepDuration.text = it[0].length.toString()
nextStep.text = "${it[1].name} : ${it[1].length.toString()}"
}
}
})
I have an app that launches the majority of the time, but every 7 or so launches it crashes with the error:
kotlin.UninitializedPropertyAccessException: lateinit property weekdayList has not been initialized
This is a clear error, I'm just not sure how to ensure the variable is initialized early enough in the context of my app.
Things I have tried
I tried moving variables around, making "inner" and "outer"
variables, one within onCreate and an underscore led variable as
the class variable.
Changing the viewmodel so that it will wait until the call to the db has finished (I
couldn't make this work, but mostly because I wasn't sure how to do it).
I think the problem is in the onCreate function, and that the weekday observe isn't setting the value of the variable faster than the task observe (where the weekdayList variable is needed) is called?
Edit 1
I referenced this but I end up with a similar error
java.lang.IndexOutOfBoundsException: Empty list doesn't contain element at index 1.
Edit 2
I understand how lateinit variables and nullables work at this point, I want to try and clarify this a little better.
The variable weekdayList needs to be initialized to the correct list before I hit the observe for the taskList, otherwise the app will crash.
I have tried setting the variable to be nullable, and Iend up with:
skipping parts of the program when it's null (not an option)
crashing with a null pointer exception (if set to non-nullable)
no tasks get assigned to any day, which means no recyclerviews get updated, thus making the app appear to contain no tasks when it does.
weekday buttons that don't work because there is no weekdayList for them to compare against to launch the next activity
My problem doesn't stand in figuring out if it's null or not, it's trying to guarantee that it won't be null.
Sorry for the confusion
Main Activity
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
private val plannerViewModel: PlannerViewModel by viewModels {
PlannerViewModelFactory((application as PlannerApplication).repository)
}
private var weekdayList: List<Weekday> = listOf()
private var taskList: List<Task> = listOf()
private var taskDayList = mutableListOf<Task>()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
val clearButtonText = binding.clearCardText
val sundayButtonText = binding.sundayCardText
val mondayButtonText = binding.mondayCardText
val tuesdayButtonText = binding.tuesdayCardText
val wednesdayButtonText = binding.wednesdayCardText
val thursdayButtonText = binding.thursdayCardText
val fridayButtonText = binding.fridayCardText
val saturdayButtonText = binding.saturdayCardText
val sundayRv: RecyclerView = binding.sundayRv
val sundayAdapter = TaskRvAdapter(null)
sundayRv.adapter = sundayAdapter
sundayRv.layoutManager = LinearLayoutManager(this)
val mondayRv: RecyclerView = binding.mondayRv
val mondayAdapter = TaskRvAdapter(null)
mondayRv.adapter = mondayAdapter
mondayRv.layoutManager = LinearLayoutManager(this)
val tuesdayRv: RecyclerView = binding.tuesdayRv
val tuesdayAdapter = TaskRvAdapter(null)
tuesdayRv.adapter = tuesdayAdapter
tuesdayRv.layoutManager = LinearLayoutManager(this)
val wednesdayRv: RecyclerView = binding.wednesdayRv
val wednesdayAdapter = TaskRvAdapter(null)
wednesdayRv.adapter = wednesdayAdapter
wednesdayRv.layoutManager = LinearLayoutManager(this)
val thursdayRv: RecyclerView = binding.thursdayRv
val thursdayAdapter = TaskRvAdapter(null)
thursdayRv.adapter = thursdayAdapter
thursdayRv.layoutManager = LinearLayoutManager(this)
val fridayRv: RecyclerView = binding.fridayRv
val fridayAdapter = TaskRvAdapter(null)
fridayRv.adapter = fridayAdapter
fridayRv.layoutManager = LinearLayoutManager(this)
val saturdayRv: RecyclerView = binding.saturdayRv
val saturdayAdapter = TaskRvAdapter(null)
saturdayRv.adapter = saturdayAdapter
saturdayRv.layoutManager = LinearLayoutManager(this)
// Setting day card names
clearButtonText.text = "Clear"
sundayButtonText.text = "Sun"
mondayButtonText.text = "Mon"
tuesdayButtonText.text = "Tue"
wednesdayButtonText.text = "Wed"
thursdayButtonText.text = "Thu"
fridayButtonText.text = "Fri"
saturdayButtonText.text = "Sat"
sundayButtonText.text = "Sun"
plannerViewModel.allWeekdays.observe(this, {
weekdayList = it
})
plannerViewModel.allTasks.observe(this, { tasks ->
taskList = tasks
taskDayList = mutableListOf()
for (i in 1..7) {
taskDayList = sortTasks(weekdayList[i], taskList)
when (i) {
1 -> {
sundayAdapter.submitList(taskDayList)
toggleVisibility(taskDayList, binding.sundayInner,
binding.sundayCardText, sundayRv, binding.sundayNoTasks)
}
2 -> {
mondayAdapter.submitList(taskDayList)
toggleVisibility(taskDayList, binding.mondayInner,
binding.mondayCardText, mondayRv, binding.mondayNoTasks)
}
3 -> {
tuesdayAdapter.submitList(taskDayList)
toggleVisibility(taskDayList, binding.tuesdayInner,
binding.tuesdayCardText, tuesdayRv, binding.tuesdayNoTasks)
}
4 -> {
wednesdayAdapter.submitList(taskDayList)
toggleVisibility(taskDayList, binding.wednesdayInner,
binding.wednesdayCardText, wednesdayRv, binding.wednesdayNoTasks)
}
5 -> {
thursdayAdapter.submitList(taskDayList)
toggleVisibility(taskDayList, binding.thursdayInner,
binding.thursdayCardText, thursdayRv, binding.thursdayNoTasks)
}
6 -> {
fridayAdapter.submitList(taskDayList)
toggleVisibility(taskDayList, binding.fridayInner,
binding.fridayCardText, fridayRv, binding.fridayNoTasks)
}
7 -> {
saturdayAdapter.submitList(taskDayList)
toggleVisibility(taskDayList, binding.saturdayInner,
binding.saturdayCardText, saturdayRv, binding.saturdayNoTasks)
}
}
}
})
}
private fun toggleVisibility(taskDayList: List<Task>, inner: ConstraintLayout,
cardText: View, rv: RecyclerView, noTask: View) {
if (taskDayList.count() == 0 ) {
val newConstraintSet = ConstraintSet()
newConstraintSet.clone(inner)
newConstraintSet.connect(noTask.id, ConstraintSet.TOP,
cardText.id, ConstraintSet.BOTTOM)
newConstraintSet.applyTo(inner)
newConstraintSet.connect(cardText.id, ConstraintSet.BOTTOM,
noTask.id, ConstraintSet.TOP)
newConstraintSet.applyTo(inner)
rv.visibility = View.GONE
noTask.visibility = View.VISIBLE
Log.i("this", "ran zero")
} else {
val newConstraintSet = ConstraintSet()
newConstraintSet.clone(inner)
newConstraintSet.connect(rv.id, ConstraintSet.TOP,
cardText.id, ConstraintSet.BOTTOM)
newConstraintSet.applyTo(inner)
newConstraintSet.connect(cardText.id, ConstraintSet.BOTTOM,
rv.id, ConstraintSet.TOP)
newConstraintSet.applyTo(inner)
rv.visibility = View.VISIBLE
noTask.visibility = View.GONE
Log.i("this", "ran else")
}
}
private fun sortTasks(day: Weekday, tasks: List<Task>): MutableList<Task> {
val newAdapterList = mutableListOf<Task>()
tasks.forEach {
if (it.weekdayId == day.id) {
newAdapterList.add(it)
}
}
return newAdapterList
}
private fun startWeekdayActivity(day: Weekday) {
val intent = Intent(this, WeekdayActivity::class.java)
intent.putExtra("dayId", day.id)
this.startActivity(intent)
}
private fun clearDb(taskList: List<Task>) {
val alertDialog: AlertDialog = this.let { outerIt ->
val builder = AlertDialog.Builder(outerIt)
builder.apply {
setPositiveButton("Clear",
DialogInterface.OnClickListener { dialog, id ->
if (taskList.count() == 0) {
Toast.makeText(context, "No tasks to clear", Toast.LENGTH_SHORT).show()
} else {
plannerViewModel.deleteAllTasks()
Toast.makeText(context, "Tasks cleared", Toast.LENGTH_SHORT).show()
}
})
setNegativeButton("Cancel",
DialogInterface.OnClickListener { dialog, id ->
// User cancelled the dialog
})
}
.setTitle("Clear tasks?")
.setMessage("Are you sure you want to clear the weeks tasks?")
builder.create()
}
alertDialog.show()
}
private fun checkDay(dayIn: String, weekdayList: List<Weekday>) {
weekdayList.forEach {
if (dayIn == "clear_card" && it.day == "Clear") {
clearDb(taskList)
} else {
val dayInAbr = dayIn.substring(0, 3).toLowerCase(Locale.ROOT)
val dayOutAbr = it.day.substring(0, 3).toLowerCase(Locale.ROOT)
if (dayInAbr == dayOutAbr) {
startWeekdayActivity(it)
}
}
}
}
fun buttonClick(view: View) {
when (view.id) {
R.id.clear_card -> checkDay(view.context.resources.getResourceEntryName(R.id.clear_card).toString(), weekdayList)
R.id.sunday_card -> checkDay(view.context.resources.getResourceEntryName(R.id.sunday_card).toString(), weekdayList)
R.id.monday_card -> checkDay(view.context.resources.getResourceEntryName(R.id.monday_card).toString(), weekdayList)
R.id.tuesday_card -> checkDay(view.context.resources.getResourceEntryName(R.id.tuesday_card).toString(), weekdayList)
R.id.wednesday_card -> checkDay(view.context.resources.getResourceEntryName(R.id.wednesday_card).toString(), weekdayList)
R.id.thursday_card -> checkDay(view.context.resources.getResourceEntryName(R.id.thursday_card).toString(), weekdayList)
R.id.friday_card -> checkDay(view.context.resources.getResourceEntryName(R.id.friday_card).toString(), weekdayList)
R.id.saturday_card -> checkDay(view.context.resources.getResourceEntryName(R.id.saturday_card).toString(), weekdayList)
}
}
}
Viewmodel
class PlannerViewModel(private val repository: DbRepository) : ViewModel() {
val allWeekdays: LiveData<List<Weekday>> = repository.allWeekdays.asLiveData()
val allTasks: LiveData<List<Task>> = repository.allTasks.asLiveData()
fun insertWeekday(weekday: Weekday) = viewModelScope.launch {
repository.insertWeekday(weekday)
}
fun insertTask(task: Task) = viewModelScope.launch {
repository.insertTask(task)
}
fun deleteTask(task: Task) = viewModelScope.launch {
repository.deleteTask(task)
}
fun deleteAllTasks() = viewModelScope.launch {
repository.deleteAllTasks()
}
}
class PlannerViewModelFactory(private val repository: DbRepository) : ViewModelProvider.Factory {
override fun <T : ViewModel?> create(modelClass: Class<T>): T {
if (modelClass.isAssignableFrom(PlannerViewModel::class.java)) {
#Suppress("UNCHECKED_CAST")
return PlannerViewModel(repository) as T
}
throw IllegalArgumentException("Unknown ViewModel class")
}
}
A variable declared as lateinit just means that you are sure that when the object is dereferenced it will not be null. In your case you are calling a method from weekdayList object before it is assigned a value. It is important to understand the concept clearly and why your code works.
Happy Coding!
You can use the "isInitialized" method, for checking "lateinit" variable is initialized or not.
Please refer the below article for the this-
https://blog.mindorks.com/how-to-check-if-a-lateinit-variable-has-been-initialized
lateinit is a way for you to have a var without an initial value when you declare it. It's a nice way to avoid taking something that will never be null, and making it nullable (and having to null check it forever) just so you can temporarily set it to null as a placeholder that nothing will ever see.
What you're doing is promising the compiler "ok, I'm not going to provide a value when the class is constructed, but I promise I'll set it to something before anything tries to read it". You're telling the compiler to trust you, that you know how your code works, and you can guarantee it'll all be ok.
Your problem is that it seems you can't guarantee that things won't try to read that property before you write to it. Your state can either be "has a value", or "doesn't have a value", and the rest of your code could encounter either state.
The "no value" state is basically null, so you should probably make the variable nullable instead, and initialise it as null. Kotlin has all that nice null-safety stuff to help your code handle it, until you do get a value. lateinit seems like the wrong tool for the job, even if you check ::isInitialized it's just making your life a lot harder when the null-checking stuff is right there!
Use lazy properties , refer to this doc for more informations:
assuming weekDayList is the property you want to successfully initialize ->
private var weekDayList: List<WeekDay> by lazy {
//return your first value
listOf<WeekDay>()
}
Here is a useful link about LifeCycleAware Lazy properties: blog Although, it is not required.
A solution with help from cactustictacs in the comments.
I moved a lot of the list dependency to a new function called setAdapterList. this allows both observes to run the function, and only the one with both lists initialized will run the code contained. I kept the variables lateinit and it seems to be working so far!
The Main Change in Main Activity
...
private fun setAdapterLists(adapterList: List<TaskRvAdapter>, rvList: List<RecyclerView>) {
if (this::weekdayList.isInitialized && this::taskList.isInitialized) {
adapterList.forEach {
taskDayList = mutableListOf()
val i = adapterList.indexOf(it)
taskDayList = sortTasks(weekdayList[i + 1], taskList)
Log.i("rvli", rvList[i].toString())
when (i) {
0 -> {
adapterList[i].submitList(taskDayList)
toggleVisibility(taskDayList, binding.sundayInner,
binding.sundayCardText, rvList[i], binding.sundayNoTasks)
}
1 -> {
adapterList[i].submitList(taskDayList)
toggleVisibility(taskDayList, binding.mondayInner,
binding.mondayCardText, rvList[i], binding.mondayNoTasks)
}
2 -> {
adapterList[i].submitList(taskDayList)
toggleVisibility(taskDayList, binding.tuesdayInner,
binding.tuesdayCardText, rvList[i], binding.tuesdayNoTasks)
}
3 -> {
adapterList[i].submitList(taskDayList)
toggleVisibility(taskDayList, binding.wednesdayInner,
binding.wednesdayCardText, rvList[i], binding.wednesdayNoTasks)
}
4 -> {
adapterList[i].submitList(taskDayList)
toggleVisibility(taskDayList, binding.thursdayInner,
binding.thursdayCardText, rvList[i], binding.thursdayNoTasks)
}
5 -> {
adapterList[i].submitList(taskDayList)
toggleVisibility(taskDayList, binding.fridayInner,
binding.fridayCardText, rvList[i], binding.fridayNoTasks)
}
6 -> {
adapterList[i].submitList(taskDayList)
toggleVisibility(taskDayList, binding.saturdayInner,
binding.saturdayCardText, rvList[i], binding.saturdayNoTasks)
}
}
}
}
}
...
I have 3 editext and I have to multiply the numbers written in the first two, and make the result appear live on the third using Android Livedata.
viewModel.num1.observe(this,
Observer { newNum1-> binding.ediText1.text = newNum1.toString() }
viewModel.num2.observe(this,
Observer { newNum2-> binding.ediText2.text = newNum2.toString() }
viewModel.num3.observe(this,
Observer { newNum3-> binding.ediText3.text = newNum3.toString() }
I tried something like this, with 2 MutableLiveData and one MediatorLivedata, but i did something wrong because it didn't update live the third EditText. Could someone help me?
class MyViewModel : ViewModel() {
private var num1 = MutableLiveData<Int>();
private var num2 = MutableLiveData<Double>();
private var mun3 = MediatorLiveData<Double>();
num3.addSource(num1, this::onChanged);
num3.addSource(num2, this::onChanged);
private fun onChanged(x : Double) {
var a = num1.value
var b = num2.value
if (a== null)
a= 0;
if (b== null)
b= 0.0;
num3.setValue(a * b);
}
}
I'm using Kotlin but i accept any kind of code, even in java.
Thank you for your patience and help!
Best regards, Mark.
Please try something like that, but be aware of nullability. One of received values can be null
fun <A, B> LiveData<A>.combineWith(b: LiveData<B>): LiveData<Pair<A?, B?>> =
MediatorLiveData<Pair<A?, B?>>().apply {
var lastA: A? = this#combineWith.value
var lastB: B? = b.value
addSource(this#combineWith) {
lastA = it
value = Pair(lastA, lastB)
}
addSource(b) {
lastB = it
value = Pair(lastA, lastB)
}
}
viewModel.num1
.combineWith(viewModel.num2)
.observe(
this,
Observer { (first, second) ->
if (first != null && second != null) {
someEditText.text = (first * second).toString()
}
}
)
That might not be your literal code, because it's not compileable. You can't pass the same function to be used as the observer for either source, since the source types are different.
Your onChanged() function doesn't use the input parameter, so you can remove that and call it from a lambda you pass to each addSource call.
You can also simplify the content of your function by using Elvis operators.
private val num1 = MutableLiveData<Int>()
private val num2 = MutableLiveData<Double>()
private val num3 = MediatorLiveData<Double>().apply {
addSource(num1) { onChanged() }
addSource(num2) { onChanged() }
}
private fun onChanged() {
val a = num1.value ?: 0
val b = num2.value ?: 0.0
num3.value = a * b
}
In my Weather app, I have a MainFragment which has a button that opens a different fragment (SearchFragment) (via replace), allows a user to select a location and then fetches weather data for that location and loads it in various views including an MPAndroid LineChart. My issue is that whenever I come back from the search fragment, although the new data is fetched for the chart and I'm calling chart.notifyDataSetChanged() & chart.invalidate() (also tried chart.postInvalidate() since it was suggested when working on another thread) after the invalidate() is called the chart simply disappears. What am i missing here?
MainFragment:
const val UNIT_SYSTEM_KEY = "UNIT_SYSTEM"
const val LATEST_CURRENT_LOCATION_KEY = "LATEST_CURRENT_LOC"
class MainFragment : Fragment() {
// Lazy inject the view model
private val viewModel: WeatherViewModel by viewModel()
private lateinit var weatherUnitConverter: WeatherUnitConverter
private val TAG = MainFragment::class.java.simpleName
// View declarations
...
// OnClickListener to handle the current weather's "Details" layout expansion/collapse
private val onCurrentWeatherDetailsClicked = View.OnClickListener {
if (detailsExpandedLayout.visibility == View.GONE) {
detailsExpandedLayout.visibility = View.VISIBLE
detailsExpandedArrow.setImageResource(R.drawable.ic_arrow_up_black)
} else {
detailsExpandedLayout.visibility = View.GONE
detailsExpandedArrow.setImageResource(R.drawable.ic_down_arrow)
}
}
// OnClickListener to handle place searching using the Places SDK
private val onPlaceSearchInitiated = View.OnClickListener {
(activity as MainActivity).openSearchPage()
}
// RefreshListener to update the UI when the location settings are changed
private val refreshListener = SwipeRefreshLayout.OnRefreshListener {
Toast.makeText(activity, "calling onRefresh()", Toast.LENGTH_SHORT).show()
swipeRefreshLayout.isRefreshing = false
}
// OnClickListener to allow navigating from this fragment to the settings one
private val onSettingsButtonClicked: View.OnClickListener = View.OnClickListener {
(activity as MainActivity).openSettingsPage()
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View {
val view = inflater.inflate(R.layout.main_fragment, container, false)
// View initializations
.....
hourlyChart = view.findViewById(R.id.lc_hourly_forecasts)
return view
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
setUpChart()
lifecycleScope.launch {
// Shows a lottie animation while the data is being loaded
//scrollView.visibility = View.GONE
//lottieAnimView.visibility = View.VISIBLE
bindUIAsync().await()
// Stops the animation and reveals the layout with the data loaded
//scrollView.visibility = View.VISIBLE
//lottieAnimView.visibility = View.GONE
}
}
#SuppressLint("SimpleDateFormat")
private fun bindUIAsync() = lifecycleScope.async(Dispatchers.Main) {
// fetch current weather
val currentWeather = viewModel.currentWeatherData
// Observe the current weather live data
currentWeather.observe(viewLifecycleOwner, Observer { currentlyLiveData ->
if (currentlyLiveData == null) return#Observer
currentlyLiveData.observe(viewLifecycleOwner, Observer { currently ->
setCurrentWeatherDate(currently.time.toDouble())
// Get the unit system pref's value
val unitSystem = viewModel.preferences.getString(
UNIT_SYSTEM_KEY,
UnitSystem.SI.name.toLowerCase(Locale.ROOT)
)
// set up views dependent on the Unit System pref's value
when (unitSystem) {
UnitSystem.SI.name.toLowerCase(Locale.ROOT) -> {
setCurrentWeatherTemp(currently.temperature)
setUnitSystemImgView(unitSystem)
}
UnitSystem.US.name.toLowerCase(Locale.ROOT) -> {
setCurrentWeatherTemp(
weatherUnitConverter.convertToFahrenheit(
currently.temperature
)
)
setUnitSystemImgView(unitSystem)
}
}
setCurrentWeatherSummaryText(currently.summary)
setCurrentWeatherSummaryIcon(currently.icon)
setCurrentWeatherPrecipProb(currently.precipProbability)
})
})
// fetch the location
val weatherLocation = viewModel.weatherLocation
// Observe the location for changes
weatherLocation.observe(viewLifecycleOwner, Observer { locationLiveData ->
if (locationLiveData == null) return#Observer
locationLiveData.observe(viewLifecycleOwner, Observer { location ->
Log.d(TAG,"location update = $location")
locationTxtView.text = location.name
})
})
// fetch hourly weather
val hourlyWeather = viewModel.hourlyWeatherEntries
// Observe the hourly weather live data
hourlyWeather.observe(viewLifecycleOwner, Observer { hourlyLiveData ->
if (hourlyLiveData == null) return#Observer
hourlyLiveData.observe(viewLifecycleOwner, Observer { hourly ->
val xAxisLabels = arrayListOf<String>()
val sdf = SimpleDateFormat("HH")
for (i in hourly.indices) {
val formattedLabel = sdf.format(Date(hourly[i].time * 1000))
xAxisLabels.add(formattedLabel)
}
setChartAxisLabels(xAxisLabels)
})
})
// fetch weekly weather
val weeklyWeather = viewModel.weeklyWeatherEntries
// get the timezone from the prefs
val tmz = viewModel.preferences.getString(LOCATION_TIMEZONE_KEY, "America/Los_Angeles")!!
// observe the weekly weather live data
weeklyWeather.observe(viewLifecycleOwner, Observer { weeklyLiveData ->
if (weeklyLiveData == null) return#Observer
weeklyLiveData.observe(viewLifecycleOwner, Observer { weatherEntries ->
// update the recyclerView with the new data
(weeklyForecastRCV.adapter as WeeklyWeatherAdapter).updateWeeklyWeatherData(
weatherEntries, tmz
)
for (day in weatherEntries) { //TODO:sp replace this with the full list once the repo issue is fixed
val zdtNow = Instant.now().atZone(ZoneId.of(tmz))
val dayZdt = Instant.ofEpochSecond(day.time).atZone(ZoneId.of(tmz))
val formatter = DateTimeFormatter.ofPattern("MM-dd-yyyy")
val formattedNowZtd = zdtNow.format(formatter)
val formattedDayZtd = dayZdt.format(formatter)
if (formattedNowZtd == formattedDayZtd) { // find the right week day whose data we want to use for the UI
initTodayData(day, tmz)
}
}
})
})
// get the hourly chart's computed data
val hourlyChartLineData = viewModel.hourlyChartData
// Observe the chart's data
hourlyChartLineData.observe(viewLifecycleOwner, Observer { lineData ->
if(lineData == null) return#Observer
hourlyChart.data = lineData // Error due to the live data value being of type Unit
})
return#async true
}
...
private fun setChartAxisLabels(labels: ArrayList<String>) {
// Populate the X axis with the hour labels
hourlyChart.xAxis.valueFormatter = IndexAxisValueFormatter(labels)
}
/**
* Sets up the chart with the appropriate
* customizations.
*/
private fun setUpChart() {
hourlyChart.apply {
description.isEnabled = false
setNoDataText("Data is loading...")
// enable touch gestures
setTouchEnabled(true)
dragDecelerationFrictionCoef = 0.9f
// enable dragging
isDragEnabled = true
isHighlightPerDragEnabled = true
setDrawGridBackground(false)
axisRight.setDrawLabels(false)
axisLeft.setDrawLabels(false)
axisLeft.setDrawGridLines(false)
xAxis.setDrawGridLines(false)
xAxis.isEnabled = true
// disable zoom functionality
setScaleEnabled(false)
setPinchZoom(false)
isDoubleTapToZoomEnabled = false
// disable the chart's legend
legend.isEnabled = false
// append extra offsets to the chart's auto-calculated ones
setExtraOffsets(0f, 0f, 0f, 10f)
data = LineData()
data.isHighlightEnabled = false
setVisibleXRangeMaximum(6f)
setBackgroundColor(resources.getColor(R.color.bright_White, null))
}
// X Axis setup
hourlyChart.xAxis.apply {
position = XAxis.XAxisPosition.BOTTOM
textSize = 14f
setDrawLabels(true)
setDrawAxisLine(false)
granularity = 1f // one hour
spaceMax = 0.2f // add padding start
spaceMin = 0.2f // add padding end
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
typeface = resources.getFont(R.font.work_sans)
}
textColor = resources.getColor(R.color.black, null)
}
// Left Y axis setup
hourlyChart.axisLeft.apply {
setDrawLabels(false)
setDrawGridLines(false)
setPosition(YAxis.YAxisLabelPosition.OUTSIDE_CHART)
isEnabled = false
isGranularityEnabled = true
// temperature values range (higher than probable temps in order to scale down the chart)
axisMinimum = 0f
axisMaximum = when (getUnitSystemValue()) {
UnitSystem.SI.name.toLowerCase(Locale.ROOT) -> 50f
UnitSystem.US.name.toLowerCase(Locale.ROOT) -> 150f
else -> 50f
}
}
// Right Y axis setup
hourlyChart.axisRight.apply {
setDrawGridLines(false)
isEnabled = false
}
}
}
ViewModel class:
class WeatherViewModel(
private val forecastRepository: ForecastRepository,
private val weatherUnitConverter: WeatherUnitConverter,
context: Context
) : ViewModel() {
private val appContext = context.applicationContext
// Retrieve the sharedPrefs
val preferences:SharedPreferences
get() = PreferenceManager.getDefaultSharedPreferences(appContext)
// This will run only when currentWeatherData is called from the View
val currentWeatherData = liveData {
val task = viewModelScope.async { forecastRepository.getCurrentWeather() }
emit(task.await())
}
val hourlyWeatherEntries = liveData {
val task = viewModelScope.async { forecastRepository.getHourlyWeather() }
emit(task.await())
}
val weeklyWeatherEntries = liveData {
val task = viewModelScope.async {
val currentDateEpoch = LocalDate.now().toEpochDay()
forecastRepository.getWeekDayWeatherList(currentDateEpoch)
}
emit(task.await())
}
val weatherLocation = liveData {
val task = viewModelScope.async(Dispatchers.IO) {
forecastRepository.getWeatherLocation()
}
emit(task.await())
}
val hourlyChartData = liveData {
val task = viewModelScope.async(Dispatchers.Default) {
// Build the chart data
hourlyWeatherEntries.observeForever { hourlyWeatherLiveData ->
if(hourlyWeatherLiveData == null) return#observeForever
hourlyWeatherLiveData.observeForever {hourlyWeather ->
createChartData(hourlyWeather)
}
}
}
emit(task.await())
}
/**
* Creates the line chart's data and returns them.
* #return The line chart's data (x,y) value pairs
*/
private fun createChartData(hourlyWeather: List<HourWeatherEntry>?): LineData {
if(hourlyWeather == null) return LineData()
val unitSystemValue = preferences.getString(UNIT_SYSTEM_KEY, "si")!!
val values = arrayListOf<Entry>()
for (i in hourlyWeather.indices) { // init data points
// format the temperature appropriately based on the unit system selected
val hourTempFormatted = when (unitSystemValue) {
UnitSystem.SI.name.toLowerCase(Locale.ROOT) -> hourlyWeather[i].temperature
UnitSystem.US.name.toLowerCase(Locale.ROOT) -> weatherUnitConverter.convertToFahrenheit(
hourlyWeather[i].temperature
)
else -> hourlyWeather[i].temperature
}
// Create the data point
values.add(
Entry(
i.toFloat(),
hourTempFormatted.toFloat(),
appContext.resources.getDrawable(determineSummaryIcon(hourlyWeather[i].icon), null)
)
)
}
Log.d("MainFragment viewModel", "$values")
// create a data set and customize it
val lineDataSet = LineDataSet(values, "")
val color = appContext.resources.getColor(R.color.black, null)
val offset = MPPointF.getInstance()
offset.y = -35f
lineDataSet.apply {
valueFormatter = YValueFormatter()
setDrawValues(true)
fillDrawable = appContext.resources.getDrawable(R.drawable.gradient_night_chart, null)
setDrawFilled(true)
setDrawIcons(true)
setCircleColor(color)
mode = LineDataSet.Mode.HORIZONTAL_BEZIER
this.color = color // line color
iconsOffset = offset
lineWidth = 3f
valueTextSize = 9f
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
valueTypeface = appContext.resources.getFont(R.font.work_sans_medium)
}
}
// create a LineData object using our LineDataSet
val data = LineData(lineDataSet)
data.apply {
setValueTextColor(R.color.colorPrimary)
setValueTextSize(15f)
}
return data
}
private fun determineSummaryIcon(icon: String): Int {
return when (icon) {
"clear-day" -> R.drawable.ic_sun
"clear-night" -> R.drawable.ic_moon
"rain" -> R.drawable.ic_precipitation
"snow" -> R.drawable.ic_snowflake
"sleet" -> R.drawable.ic_sleet
"wind" -> R.drawable.ic_wind_speed
"fog" -> R.drawable.ic_fog
"cloudy" -> R.drawable.ic_cloud_coverage
"partly-cloudy-day" -> R.drawable.ic_cloudy_day
"partly-cloudy-night" -> R.drawable.ic_cloudy_night
"hail" -> R.drawable.ic_hail
"thunderstorm" -> R.drawable.ic_thunderstorm
"tornado" -> R.drawable.ic_tornado
else -> R.drawable.ic_sun
}
}
}
LazyDeferred:
fun<T> lazyDeferred(block: suspend CoroutineScope.() -> T) : Lazy<Deferred<T>> {
return lazy {
GlobalScope.async {
block.invoke(this)
}
}
}
ScopedFragment :
abstract class ScopedFragment : Fragment(), CoroutineScope {
private lateinit var job: Job
override val coroutineContext: CoroutineContext
get() = job + Dispatchers.Main
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
job = Job()
}
override fun onDestroy() {
job.cancel()
super.onDestroy()
}
}
Without the entire environment it's really hard for me to help you debug the whole thing but I am happy to provide you with a couple of things that seem a little bit off at a first glance.
First of all I would avoid managing all CoroutinesScopes and lifecycles by yourself and it's easy to get it wrong. So I would rely on what the Android team has already done. Take a quick look here, it's really easy to setup and use. The dev experience is great.
Posting Deferred on a LiveData and awaiting on the view side looks like a code smell…
What if there's a network error?
It would result in an exception or cancellation exception being thrown.
What if the task was already perform and causes some type of UI consistency problem? These are a couple of edge cases I would not really want to handle.
Just observe a LiveData since it is its main purpose: it's a value holder and it's intended to live throught several lifecycle events in the Fragment. So once view is recreated the value is ready in the LiveData inside the ViewModel.
Your lazyDeferred function is quite smart but in the Android world it's also dangerous. Those coroutines don't live inside any lifecycle-controlled scope so they have a really high chance to end up being leaked. And trust me, you don't want any coroutines being leaked since they continue their work even after viewmodel and fragment destruction which is something you definetely don't want.
All of these are easily fixable by using the dependency I've mentioned before, which I'll paste here once more
Here's a snippet on how you could use those utilities in your ViewModel to ensure the lifecycle of things nor coroutines are causing any issues:
class WeatherViewModel(
private val forecastRepository: ForecastRepository,
context: Context
) : ViewModel() {
private val appContext = context.applicationContext
// Retrieve the sharedPrefs
val preferences:SharedPreferences
get() = PreferenceManager.getDefaultSharedPreferences(appContext)
// This will run only when currentWeatherData is called from the View
val currentWeatherData = liveData {
val task = viewModelScope.async { forecastRepository.getCurrentWeather() }
emit(task.await())
}
val hourlyWeatherEntries = liveData {
val task = viewModelScope.async { forecastRepository.getHourlyWeather() }
emit(task.await())
}
val weeklyWeatherEntries = liveData {
val task = viewModelScope.async {
val currentDateEpoch = LocalDate.now().toEpochDay()
forecastRepository.getWeekDayWeatherList(currentDateEpoch)
}
emit(task.await())
}
val weatherLocation = liveData {
val task = viewModelScope.async(Dispatchers.IO) {
forecastRepository.getWeatherLocation()
}
emit(task.await())
}
}
By using the following approach all network calls are performed in a parallel fashion and they are all tied to the viewModelScope without writing a single line of handling the CoroutineScope's life. When the ViewModel dies, so will the scope. when the view gets re-created the routines won't execute twice and values will be ready to read.
Regarding the configuration of the chart: I would highly suggest you configure the chart as soon as you have created the view, since it is highly tied together. Configuration is something you want to do just once and may cause visual bugs if some instructions are executed more than once (which I believe it could be happening to you), just saying so because I've had problems with MPAndroid using a Piechart.
More on the chart: All of the logic of constructing the LineData would be better off on a background thread and being exposed through a LiveData in the ViewModel side like you would do with all of the other
val property = liveData {
val deferred = viewModelScope.async(Dispatchers.Default) {
// Heavy building logic like:
createChartData()
}
emit(deferred.await())
}
Pro Kotlin tip: Avoid repeating yourself during those long MPAndroid configurations functions.
Instead of:
view.configureThis()
view.configureThat()
view.enabled = true
Do:
view.apply {
configureThis()
configureThat()
enabled = true
}
I'm sad that I can just give you these hints and being unable to exactly pin-point what your issue is since the bug is heavily related to what is happenning throughout the lifecycle evolution of the runtime but hopefuly this is going to be useful
Answering your comment
If one of your data-streams (LiveData) is dependent on what another data-stream (another LiveData) is going to emit you are looking for LiveData.map and LiveData.switchMap operations.
I imagine that hourlyWeatherEntries is going to be emitting values from time to time.
In that case you can use LiveData.switchMap.
What this does is that everytime the source LiveData emits a value, you're going to get a callback and you are expected to return a new live data with the new value.
You could arrange something like the following:
val hourlyChartData = hourlyWeatherEntries.switchMap { hourlyWeather ->
liveData {
val task = viewModelScope.async(Dispatchers.IO) {
createChartData(hourlyWeather)
}
emit(task.await())
}
}
Using this approach has the benefit that it is completely lazy. That means that NO COMPUTATION is going to take place UNLESS data is being actively observed by some lifecycleOwner. That just means that no callbacks are being triggered unless data is observed in the Fragment
Further explanation on map and switchMap
Since we need to do some asynchronous computation that we don't know when it's going to be done we can't use map. map applies a linear transformation between LiveDatas. Check this out:
val liveDataOfNumbers = liveData { // Returns a LiveData<Int>
viewModelScope.async {
for(i in 0..10) {
emit(i)
delay(1000)
}
}
}
val liveDataOfDoubleNumbers = liveDataOfNumbers.map { number -> number * 2}
This is really useful when the computation is linear and simple. What is happening behind the hood is that the library is handling observing and emitting values for you by means of a MediatorLiveData. What happens here is that whenever liveDataOfNumbers emits a value and liveDataOfDoubleNumbers is being observed the callback gets applied; so the liveDataOfDoubleNumbers is emitting: 0, 2, 4, 6…
The snippet above is equivalent to the following:
val liveDataOfNumbers = liveData { // Returns a LiveData<Int>
viewModelScope.async {
for(i in 0..10) {
emit(i)
delay(1000)
}
}
}
val liveDataOfDoubleNumbers = MediatorLiveData<Int>().apply {
addSource(liveDataOfNumbers) { newNumber ->
// Update MediatorLiveData value when liveDataOfNumbers creates a new number
value = newNumber * 2
}
}
But just using map is much much simpler.
Fantastic!!
Now going to your use-case. Your computation is linear but we want to defer that work to a background coroutine. So we can't exactly tell when something is going to end.
For these use-cases they have created the switchMap operator. What it does it's just the same as map but wraps everything within another LiveData. The intermediate LiveData just acts as a container for the response that is going to come from the coroutine.
So what ends up happening is:
Your coroutine publishes into intermediateLiveData
switchMap does something similar to:
return MediatorLiveData().apply {
// intermediateLiveData is what your callback generates
addSource(intermediateLiveData) { newValue -> this.value = newValue }
} as LiveData
Summing up:
1. Coroutine passes value to intermediateLiveData
2. intermediateLiveData passes value to the hourlyChartData
3. hourlyChartData passes value to the UI
And everything without adding or removing observeForever
Since the liveData {…} is a builder to help us create asynchronous LiveDatas without dealing with the hassle of instantiating them we can use it so our switchMap callback is less verbose.
The function liveData returns a live data of type LiveData<T>. If your repository call already returns a LiveData it's really simple!
val someLiveData = originalLiveData.switchMap { newValue ->
someRepositoryCall(newValue).map { returnedRepoValue -> /*your transformation code here*/}
}
Separate the setupChart and setData logics. Setup chart once out of the observer, inside the observer setData and after that call invalidate().
Try commenting out the invalidate() part and wherever you are calling your search function before it try yourlineChart.clear(); or yourlineChart.clearValues();. This will clear the previous values of the chart and will form chart with new values. So, invalidate() and chart.notifyDataSetChanged() won't not be necessary and it should solve your problem.