Develop Reference

MutableSharedFlow is being re collected again and again

I have the following ViewModel and Fragment -
class HeroesViewModel(private val heroesRepository: HeroesRepository) : ViewModel() {
private val internalUiState = MutableStateFlow<UiState>(UiState.Initial)
val uiState = internalUiState.asLiveData()
private val internalUiAction = MutableSharedFlow<UiAction>(1).apply {
tryEmit(UiAction.GetSuggestedList)
}
val uiAction = internalUiAction.asLiveData()
private val externalUiEvent = MutableSharedFlow<UiEvent>(1)
private val uiEvent = externalUiEvent.asSharedFlow()
init {
observeUiEvents()
}
private fun observeUiEvents() = viewModelScope.launch {
uiEvent.collect { event ->
when (event) {
is UiEvent.ListItemClicked -> {
navigateToHeroDetails(event.heroModel)
}
is UiEvent.SearchTextChanged -> {
getHeroesByName(event.searchText)
}
}
}
}
private fun navigateToHeroDetails(heroModel: HeroesListModel) =
submitAction(UiAction.NavigateToHeroesDetails(heroModel))
private fun getHeroesByName(name: String) = viewModelScope.launch(Dispatchers.IO) {
when (val response = heroesRepository.getHeroesByNameWithSuggestions(name)) {
is NetworkResponse.Success -> {
internalUiState.emit(UiState.Data(response.body as List<HeroesListModel>))
}
is NetworkResponse.Error -> {
response.error.message?.let { message ->
internalUiState.emit(UiState.Error(message))
}
}
else -> {}
}
}
fun getSuggestedHeroesList() = viewModelScope.launch(Dispatchers.IO) {
when (val response = heroesRepository.getSuggestedHeroesList(true)) {
is NetworkResponse.Success -> {
submitState(UiState.Data(response.body as List<HeroesListModel>))
}
is NetworkResponse.Error -> {
response.error.message?.let { message ->
submitState(UiState.Error(message))
}
}
else -> {}
}
}
private fun submitAction(uiAction: UiAction) = internalUiAction.tryEmit(uiAction)
private fun submitState(uiState: UiState) = viewModelScope.launch {
internalUiState.emit(uiState)
}
fun submitEvent(uiEvent: UiEvent) = externalUiEvent.tryEmit(uiEvent)
sealed class UiEvent {
data class SearchTextChanged(val searchText: String) : UiEvent()
data class ListItemClicked(val heroModel: HeroesListModel) : UiEvent()
}
sealed class UiState {
data class Data(val modelsListResponse: List<BaseHeroListModel>) : UiState()
data class Error(val errorMessage: String) : UiState()
object Initial : UiState()
}
sealed class UiAction {
data class NavigateToHeroesDetails(val heroModel: HeroesListModel) : UiAction()
object GetSuggestedList : UiAction()
}
}
class DashboardFragment : Fragment() {
//Class Variables - UI
private lateinit var binding: FragmentDashboardBinding
//Class Variables - Dependency Injection
private val heroesViewModel = get<HeroesViewModel>()
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
binding = FragmentDashboardBinding.inflate(inflater, container, false)
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
init()
observeUiState()
observeUiAction()
}
private fun observeUiAction() = heroesViewModel.uiAction.observe(viewLifecycleOwner) { action ->
when(action){
is HeroesViewModel.UiAction.GetSuggestedList -> {
getSuggestedHeroesList()
}
is HeroesViewModel.UiAction.NavigateToHeroesDetails -> {
navigateToHeroesDetails(action.heroModel)
}
}
}
private fun init() {
binding.heroesSearchView.setOnQueryTextListener(object : OnSearchViewOnlyTextChangedListener() {
override fun onQueryTextChange(newText: String?): Boolean {
if (newText.isNullOrEmpty()) return false
heroesViewModel.submitEvent(HeroesViewModel.UiEvent.SearchTextChanged(newText))
binding.progressBar.setVisiblyAsVisible()
return false
}
})
}
private fun observeUiState() = heroesViewModel.uiState.observe(viewLifecycleOwner) { uiAction ->
when (uiAction) {
is HeroesViewModel.UiState.Data -> {
showHeroesList(uiAction)
}
is HeroesViewModel.UiState.Error -> {
showGeneralError(uiAction)
}
HeroesViewModel.UiState.Initial -> Unit
}
}
private fun navigateToHeroesDetails(heroModel: HeroesListModel) =
findNavController().navigate(DashboardFragmentDirections.actionMainFragmentToHeroesDetailsFragment(heroModel))
private fun showHeroesList(result: HeroesViewModel.UiState.Data) {
binding.heroesList.setContent {
LazyColumn {
items(result.modelsListResponse.toList()) { model ->
if (model is HeroListSeparatorModel)
HeroesListSeparatorItem(model)
else if (model is HeroesListModel)
HeroesListItem(model) {
heroesViewModel.submitEvent(HeroesViewModel.UiEvent.ListItemClicked(model))
}
}
}
}
binding.progressBar.setVisiblyAsGone()
}
private fun showGeneralError(result: HeroesViewModel.UiState.Error) {
Toast.makeText(requireContext(), result.errorMessage, Toast.LENGTH_LONG).show()
binding.progressBar.setVisiblyAsGone()
}
private fun getSuggestedHeroesList() {
heroesViewModel.getSuggestedHeroesList()
binding.progressBar.setVisiblyAsVisible()
}
}
As you can see, I have the replayCache set to 1 in internalUiAction but the value keeps emitting itself. When I navigate using the navigateToHeroesDetails() method and go back using the navigation bar I immediately observe the last uiAction emitted value which is NavigateToHeroesDetails, causing me to navigate again and again to the heroes details screen. This is an endless loop of navigation.
As far as a hint for a solution, if I double tap the navigation 2 times quickly it does indeed go back to the first Fragment. Seems like I am missing something related to SharedFlow

delay init methods in ViewModel

I have following project in Github : https://github.com/AliRezaeiii/TMDb-Paging
I have to postDelay calling methods in my ViewModel since datasource is not initialized :
abstract class DetailViewModel(private val item: TmdbItem) : BaseViewModel() {
private val handler = Handler(Looper.getMainLooper())
val trailers: ObservableList<Video> = ObservableArrayList()
val isTrailersVisible = ObservableBoolean(false)
private val _cast = MutableLiveData<List<Cast>>()
val cast: LiveData<List<Cast>> = _cast
val isCastVisible = ObservableBoolean(false)
init {
handler.postDelayed({
showTrailers()
showCast()
}, 100)
}
protected abstract fun getTrailers(id: Int): Observable<List<Video>>
protected abstract fun getCast(id: Int): Observable<List<Cast>>
private fun showTrailers() {
EspressoIdlingResource.increment() // App is busy until further notice
compositeDisposable.add(getTrailers(item.id)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.doFinally {
if (!EspressoIdlingResource.getIdlingResource().isIdleNow) {
EspressoIdlingResource.decrement() // Set app as idle.
}
}
.subscribe({ videos ->
if (videos.isNotEmpty()) {
isTrailersVisible.set(true)
}
with(trailers) {
clear()
addAll(videos)
}
}
) { throwable -> Timber.e(throwable) })
}
private fun showCast() {
EspressoIdlingResource.increment() // App is busy until further notice
compositeDisposable.add(getCast(item.id)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.doFinally {
if (!EspressoIdlingResource.getIdlingResource().isIdleNow) {
EspressoIdlingResource.decrement() // Set app as idle.
}
}
.subscribe({ cast ->
if (cast.isNotEmpty()) {
isCastVisible.set(true)
}
this._cast.postValue(cast)
}
) { throwable -> Timber.e(throwable) })
}
}
And here is my Fragment :
abstract class DetailFragment<T : TmdbItem>
: BaseDaggerFragment(), CastClickCallback {
protected abstract fun getViewModel(): DetailViewModel
protected abstract fun getLayoutId(): Int
protected abstract fun initViewBinding(root: View): ViewDataBinding
protected abstract fun getTmdbItem(): T
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
val viewModel = getViewModel()
val root = inflater.inflate(getLayoutId(), container, false)
initViewBinding(root).apply {
setVariable(BR.vm, viewModel)
lifecycleOwner = viewLifecycleOwner
}
with(root) {
with(activity as AppCompatActivity) {
setupActionBar(details_toolbar) {
setDisplayShowTitleEnabled(false)
setDisplayHomeAsUpEnabled(true)
setDisplayShowHomeEnabled(true)
}
}
summary_label.visibleGone(getTmdbItem().overview.trim().isNotEmpty())
// Make the MotionLayout draw behind the status bar
details_motion.systemUiVisibility = View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN or
View.SYSTEM_UI_FLAG_LAYOUT_STABLE
summary.setOnClickListener {
val maxLine = resources.getInteger(R.integer.max_lines)
summary.maxLines = if (summary.maxLines > maxLine) maxLine else Int.MAX_VALUE
}
viewModel.cast.observe(viewLifecycleOwner, Observer {
it?.apply {
val adapter = CastAdapter(it, this#DetailFragment)
cast_list.apply {
setHasFixedSize(true)
cast_list.adapter = adapter
}
}
})
with(details_rv) {
postDelayed({ scrollTo(0, 0) }, 100)
}
}
return root
}
}
And BaseDaggerFragment :
open class BaseDaggerFragment : DaggerFragment() {
#Inject
lateinit var dataSource: RemoteDataSource
}
Could be any better solution than :
init {
handler.postDelayed({
showTrailers()
showCast()
}, 100)
}

You can lazy initialize like this way
private val users:MutableLiveData<List<Cast>> by lazy {
MutableLiveData().also {
showTrailers()
showCast()
}
}
more details refer ViewModel

Initialization of a fragment causes the animation lag

While writing an Android app, I encountered a problem with a stuttering animation. I use AHBottomNavigation for navigation, FragNav is for swapping fragments and FlexibleAdapter for RecyclerView.
The application is built from one activity and five fragments. When I try to switch to the first fragment in the application, the BottomNavigation animation freez for a moment. It looks very unsightly. The second time I choose the same fragment, everything works smoothly. It seems to me that it is the fault to initialize the views in the fragment, but I have no idea how to do it differently.
AHBottomNavigation https://github.com/aurelhubert/ahbottomnavigation
FragNav https://github.com/ncapdevi/FragNav
FlexibleAdapter https://github.com/davideas/FlexibleAdapter
Fragment
class GradeFragment : BaseFragment(), GradeView {
#Inject
lateinit var presenter: GradePresenter
private val gradeAdapter = FlexibleAdapter<AbstractFlexibleItem<*>>(null, null, true)
companion object {
fun newInstance() = GradeFragment()
}
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
return inflater.inflate(R.layout.fragment_grade, container, false)
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
presenter.run {
attachView(this#GradeFragment)
loadData()
}
}
override fun initView() {
gradeAdapter.run {
isAutoCollapseOnExpand = true
isAutoScrollOnExpand = true
setOnUpdateListener { presenter.onUpdateDataList(it) }
setOnItemClickListener { position ->
getItem(position).let {
if (it is GradeItem) {
GradeDialog.newInstance(it.grade).show(fragmentManager, it.toString())
}
}
}
}
gradeRecycler.run {
layoutManager = SmoothScrollLinearLayoutManager(context)
adapter = gradeAdapter
}
gradeSwipe.setOnRefreshListener { presenter.loadData(forceRefresh = true) }
}
override fun updateData(data: List<GradeHeader>) {
gradeAdapter.updateDataSet(data, true)
}
override fun isViewEmpty(): Boolean = gradeAdapter.isEmpty
override fun showEmptyView(show: Boolean) {
gradeEmpty.visibility = if (show) VISIBLE else GONE
}
override fun showProgress(show: Boolean) {
gradeProgress.visibility = if (show) VISIBLE else GONE
}
override fun setRefresh(show: Boolean) {
gradeSwipe.isRefreshing = show
}
Presenter
class GradePresenter #Inject constructor(
private val errorHandler: ErrorHandler,
private val schedulers: SchedulersManager,
private val gradeRepository: GradeRepository,
private val sessionRepository: SessionRepository) : BasePresenter<GradeView>(errorHandler) {
override fun attachView(view: GradeView) {
super.attachView(view)
view.initView()
}
fun loadData(forceRefresh: Boolean = false) {
disposable.add(sessionRepository.getSemesters()
.map { it.single { semester -> semester.current } }
.flatMap { gradeRepository.getGrades(it, forceRefresh) }
.map { it.groupBy { grade -> grade.subject } }
.map { createGradeItems(it) }
.subscribeOn(schedulers.backgroundThread())
.observeOn(schedulers.mainThread())
.doFinally { view?.setRefresh(false) }
.doOnSuccess { if (it.isEmpty()) view?.showEmptyView(true) }
.doOnError { view?.run { if (isViewEmpty()) showEmptyView(true) } }
.subscribe({ view?.updateData(it) }) { errorHandler.proceed(it) })
}
private fun createGradeItems(items: Map<String, List<Grade>>): List<GradeHeader> {
return items.map {
val gradesAverage = calcAverage(it.value)
GradeHeader().apply {
subject = it.key
average = view?.run {
if (gradesAverage == 0f) emptyAverageString()
else averageString().format(gradesAverage)
}.orEmpty()
number = view?.gradeNumberString(it.value.size).orEmpty()
subItems = (it.value.map { item ->
GradeItem().apply {
grade = item
weightString = view?.weightString().orEmpty()
valueColor = getValueColor(item.value)
}
})
}
}
}
fun onUpdateDataList(size: Int) {
if (size != 0) view?.showProgress(false)
}

After a few days, I managed to solve the problem by updating the SDK to version 28. RecyclerView no longer causes animation jams when inflating

Why l can`t set listener in Kotlin?

I have OnClickInterface (with method fun onClickShape()) Main.class, and FlipFragment.class and ImageView (which called image in my code). My goal is make listener for image.
interface OnClickInterface {
fun onClickShape()
}
MainActivity
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
initTabs()
var flip = FlipFragment()
flip.listener = object : OnClickInterface {
override fun onClickShape() {
Log.d("MainActivity", "Shape Pressed")
ToastUtils.showSuccessMessage(baseContext, "sometext")
}
}
}
fun initTabs() {
var adapter = TabsPagerFragmentAdapter(supportFragmentManager)
mViewPager.adapter = adapter
mTabLayout.setupWithViewPager(mViewPager)
}
}
onCreate in FlipFragment
var image = view.findViewById<ImageView>(R.id.fShapeView)
image.setOnClickListener(View.OnClickListener {
Log.d("FlipFragment", "PRESSED")
if (listener != null)
listener!!.onClickShape()
})
App was loading well, without errors. But when I pressed in the image I show in my log FlipFragment: PRESSED that's mean that my application call method from FragmentFlip, not override method from MainActivity. Why?
I searched error . My app show NPE here.
flip.listener = object : OnClickInterface {
override fun onClickShape() {
Log.d("MainActivity", "Shape Pressed")
ToastUtils.showSuccessMessage(baseContext, "someText")
}}
Why listener = null . I defined it with anonymous class.
All code in FlipFragment
class FlipFragment : Fragment() {
private var layout = R.layout.view_flip
var listener: OnClickInterface? = null
override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
var view: View
view = inflater!!.inflate(layout, container, false)
var image = view.findViewById<ImageView>(R.id.fShapeView)
image.setOnClickListener(View.OnClickListener {
Log.d("FlipFragment", "PRESSED")
if (listener != null){
listener!!.onClickShape()}
})
return view
}
companion object {
fun getInstanse(): FlipFragment {
var args = Bundle()
var flipFragment = FlipFragment()
flipFragment.arguments = args
return flipFragment
}
}
}
If you need all code it is FragmentPagerAdapter.class
class TabsPagerFragmentAdapter(fm: FragmentManager?) : FragmentPagerAdapter(fm) {
var tabs: Array<String> = arrayOf("Flip", "Multi")
override fun getItem(position: Int) = when(position){
0 -> FlipFragment.getInstanse()
1 -> Mulit.getInstanse() //it is empty now
else -> FlipFragment.getInstanse()
}
override fun getPageTitle(position: Int) = tabs[position]
override fun getCount() = tabs.size
}

How to call baseactivity function from viewmodel in android

Hi I have LoginActivity and LoginViewModel and some more classes. I have showLoading and hideLoading in the BaseActivity so it can be accessible from each activity.
I am able to call LoginActivity method from the LoginViewModel like mNavigator?.startForgotPasswordActivity()
I want to call it from the LoginViewModel then what the way to do it using MVVM ? or I am going with wrong approach. Please suggest what is the correct way to do this ?
BaseActivity.kt
abstract class BaseActivity : AppCompatActivity(), AnkoLogger {
private val progressBar: ProgressBar? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
protected fun getToolbar(): Toolbar {
val toolbar: Toolbar = findViewById(R.id.toolbar)
setSupportActionBar(toolbar)
return toolbar
}
protected fun performDependencyInjection() {
AndroidInjection.inject(this);
}
#TargetApi(Build.VERSION_CODES.M)
fun requestPermissionsSafely(permissions: Array<String>, requestCode: Int) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
requestPermissions(permissions, requestCode)
}
}
#TargetApi(Build.VERSION_CODES.M)
fun hasPermission(permission: String): Boolean {
return Build.VERSION.SDK_INT < Build.VERSION_CODES.M || checkSelfPermission(permission) == PackageManager.PERMISSION_GRANTED
}
fun isNetworkConnected(): Boolean {
return NetworkUtils.isNetworkConnected(applicationContext)
}
fun showLoading() {
hideLoading()
// show progress bar
}
fun hideLoading() {
// hide progress bar
}
}
LoginActivity.kt
class LoginActivity : BaseActivity(), LoginNavigator {
#Inject
lateinit var loginViewModel: LoginViewModel
override fun onCreate(savedInstanceState: Bundle?) {
performDependencyInjection()
super.onCreate(savedInstanceState)
val activityLoginBinding: ActivityLoginBinding = DataBindingUtil.setContentView<ActivityLoginBinding>(this, R.layout.activity_login)
activityLoginBinding.loginViewModel = loginViewModel
loginViewModel.mNavigator = this
}
override fun startHomeActivity() {
TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
}
override fun startRegistrationActivity() {
startActivity(Intent(this, RegistrationActivity::class.java))
}
override fun startForgotPasswordActivity() {
startActivity(Intent(this, ForgotPasswordActivity::class.java))
}
override fun handleError(throwable: Throwable) {
TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
}
}
LoginViewModel.kt
class LoginViewModel : BaseViewModel<LoginNavigator>(), AnkoLogger {
val emailField = ObservableField<String>()
private val email: String
get() = emailField.get()
val passwordField = ObservableField<String>()
private val password: String
get() = passwordField.get()
#Suppress("PARAMETER_NAME_CHANGED_ON_OVERRIDE")
fun login(view: View) {
if (isEmailAndPasswordValid(email, password)) {
ApiHelperImpl().doServerLoginApiCall(email, password)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribeWith(object : CallbackWrapper<LoginResponse>() {
override fun onSuccess(loginResponse: LoginResponse) {
info { loginResponse }
}
})
}
}
/**
* Validate email and password. It checks email and password is empty or not
* and validate email address is correct or not
* #param email email address for login
* #param password password for login
* #return true if email and password pass all conditions else false
*/
private fun isEmailAndPasswordValid(email: String, password: String): Boolean {
if (email.isEmpty()) return false
if (!Patterns.EMAIL_ADDRESS.matcher(email).matches()) return false
if (password.isEmpty()) return false
return true
}
}
BaseViewModel.kt
abstract class BaseViewModel<N> {
var mNavigator: N? = null
}

There can be 2 approach for same
1) Use all functions i.e related to UI update or UI event listener from a view (Activity or Fragment) according to mvp and from viewmodel only try to manage data like api's and other logic
class LoginActivity : BaseActivity(), LoginNavigator {
#Inject
lateinit var mLoginViewModel: LoginViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_login)
mLoginViewModel.mNavigator = this
callApi()
}
private fun callApi() {
showLoading()
mLoginViewModel.callApi()
}
override fun openHomeScreen(model: Model) {
hideLoading()
showSnackBar(constraint_root, model.Domain)
}
}
class LoginViewModel(sessionManager: SessionManager, requestInterface: RequestInterface) : BaseViewModel<LoginNavigator>(sessionManager, requestInterface) {
fun callApi() {
requestInterface.getServiceIP()
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(this::handleResponse, this::handleError)
}
private fun handleResponse(model: Model) {
if (model.Domain == null) {
mNavigator!!.openHomeScreen(model)
} else {
}
}
private fun handleError(error: Throwable) {
error.printStackTrace()
}
}
2)
In Login interface add a function
interface LoginNavigator {
fun openHomeScreen()
fun getActivity(): BaseActivity
}
In LoginActivity override the function and return
override fun getActivity(): BaseActivity = this
Now using navigator you can access base activity & call show/hide loader function
mNavigator!!.getActivity().showLoading()