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MainActivity cannot be cast to interface error when implementing interface from child fragment in parent fragment

I have this app in which I have a parent fragment, which has 2 child fragments in a ViewPager2 object.
One of the child fragments has an interface to communicate changes on its menu to the parent fragment.
The child fragment in question is TasksListFragment.kt and the parent fragment is TodayFragment.kt
When I try to initialize the interface in the child fragment onAttach() function, I get
FATAL EXCEPTION: main Process: com.rajchenbergstudios.hoygenda, PID:
java.lang.ClassCastException: com.rajchenbergstudios.hoygenda.ui.activity.MainActivity cannot be cast to com.rajchenbergstudios.hoygenda.ui.todaylists.taskslist.TasksListFragment$ChildFragmentListener
I don't understand why I get this error, and it says MainActivity, when the parent is a fragment which is the one implementing the interface in the first place, not the MainActivity.
I have everything set up correctly:
I have an interface in the child fragment
The interface is used on the child fragment onCreateMenu to pass the menu object to its interface function onFragmentMenuChanged(menu: Menu)
I override the child fragment's onAttach() and initialize the interface:
override fun onAttach(context: Context) {
super.onAttach(context)
childFragmentListener = context as ChildFragmentListener
}
I write a function called setListener() which is called from the parent fragment to pass its context this to the function parameter which assigns it to the childFragment listener
fun setListener(listener: ChildFragmentListener) {
this.childFragmentListener = listener
}
The parent fragment implements the child fragment listener as seen in the TodayFragment.kt file
Can you tell me what am I doing wrong or how to implement an interface to effectively communicate from child fragment back to its parent fragment?
TasksListFragment.kt
#ExperimentalCoroutinesApi
#AndroidEntryPoint
class TasksListFragment : Fragment(R.layout.fragment_child_tasks_list), TasksListAdapter.OnItemClickListener {
private val viewModel: TasksListViewModel by viewModels()
private lateinit var searchView: SearchView
private lateinit var childFragmentListener: ChildFragmentListener
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val binding = FragmentChildTasksListBinding.bind(view)
val tasksListAdapter = TasksListAdapter(this)
binding.apply {
tasksListRecyclerview.layoutTasksListRecyclerview.apply {
adapter = tasksListAdapter
layoutManager = LinearLayoutManager(requireContext())
setHasFixedSize(true)
}
ItemTouchHelper(object: ItemTouchHelper.SimpleCallback(0,
ItemTouchHelper.LEFT or ItemTouchHelper.RIGHT){
override fun onMove(
recyclerView: RecyclerView,
viewHolder: RecyclerView.ViewHolder,
target: RecyclerView.ViewHolder
): Boolean {
return false
}
override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {
val task = tasksListAdapter.currentList[viewHolder.adapterPosition]
viewModel.onTaskSwiped(task)
}
}).attachToRecyclerView(tasksListRecyclerview.layoutTasksListRecyclerview)
}
loadObservable(binding, tasksListAdapter)
loadTasksEventCollector()
loadMenu()
}
private fun loadObservable(binding: FragmentChildTasksListBinding, tasksListAdapter: TasksListAdapter) {
viewModel.tasks.observe(viewLifecycleOwner){ tasksList ->
binding.apply {
HGDAViewStateUtils.apply {
if (tasksList.isEmpty()) {
setViewVisibility(tasksListRecyclerview.layoutTasksListRecyclerview, visibility = View.INVISIBLE)
setViewVisibility(tasksListLayoutNoData.layoutNoDataLinearlayout, visibility = View.VISIBLE)
} else {
setViewVisibility(tasksListRecyclerview.layoutTasksListRecyclerview, visibility = View.VISIBLE)
setViewVisibility(tasksListLayoutNoData.layoutNoDataLinearlayout, visibility = View.INVISIBLE)
tasksListAdapter.submitList(tasksList)
}
}
}
}
}
/**
* TasksListViewModel.TaskEvent.ShowUndoDeleteTaskMessage: Stays in this class. It asks for components relevant to this class.
* TasksListViewModel.TaskEvent.NavigateToEditTaskScreen: Stays in this class. The method it overrides comes from task list adapter.
* TasksListViewModel.TaskEvent.NavigateToDeleteAllCompletedScreen: Stays in this class. Relevant to menu which is in this class.
* TasksListViewModel.TaskEvent.NavigateToDeleteAllScreen: Stays in this class. Relevant to menu which is in this class.
*/
private fun loadTasksEventCollector() {
viewLifecycleOwner.lifecycleScope.launchWhenStarted {
viewModel.tasksEvent.collect { event ->
when (event) {
is TasksListViewModel.TaskEvent.ShowUndoDeleteTaskMessage -> {
Snackbar
.make(requireView(), "Task deleted", Snackbar.LENGTH_LONG)
.setAction("UNDO"){
viewModel.onUndoDeleteClick(event.task)
}
.show()
}
is TasksListViewModel.TaskEvent.NavigateToEditTaskScreen -> {
val action = TodayFragmentDirections
.actionTodayFragmentToTaskAddEditFragment(task = event.task, title = "Edit task", taskinset = null, origin = 1)
findNavController().navigate(action)
}
is TasksListViewModel.TaskEvent.NavigateToAddTaskToSetBottomSheet -> {
val action = TasksListFragmentDirections.actionGlobalSetBottomSheetDialogFragment(task = event.task, origin = 1)
findNavController().navigate(action)
}
is TasksListViewModel.TaskEvent.NavigateToDeleteAllCompletedScreen -> {
val action = TasksListFragmentDirections
.actionGlobalTasksDeleteAllDialogFragment(origin = 1)
findNavController().navigate(action)
}
is TasksListViewModel.TaskEvent.NavigateToDeleteAllScreen -> {
val action = TasksListFragmentDirections
.actionGlobalTasksDeleteAllDialogFragment(origin = 3)
findNavController().navigate(action)
}
}.exhaustive
}
}
}
private fun loadMenu(){
val menuHost: MenuHost = requireActivity()
menuHost.addMenuProvider(object: MenuProvider {
override fun onCreateMenu(menu: Menu, menuInflater: MenuInflater) {
childFragmentListener.onFragmentChanged(menu)
menuInflater.inflate(R.menu.menu_tasks_list_fragment, menu)
val searchItem = menu.findItem(R.id.tasks_list_menu_search)
searchView = searchItem.actionView as SearchView
val pendingQuery = viewModel.searchQuery.value
if (pendingQuery != null && pendingQuery.isNotEmpty()) {
searchItem.expandActionView()
searchView.setQuery(pendingQuery, false)
}
searchView.OnQueryTextChanged{ searchQuery ->
viewModel.searchQuery.value = searchQuery
}
viewLifecycleOwner.lifecycleScope.launchWhenStarted {
menu.findItem(R.id.tasks_list_menu_hide_completed).isChecked =
viewModel.preferencesFlow.first().hideCompleted
}
}
override fun onMenuItemSelected(menuItem: MenuItem): Boolean {
return when (menuItem.itemId) {
R.id.tasks_list_menu_sort_by_date -> {
viewModel.onSortOrderSelected(SortOrder.BY_DATE)
true
}
R.id.tasks_list_menu_sort_by_name -> {
viewModel.onSortOrderSelected(SortOrder.BY_NAME)
true
}
R.id.tasks_list_menu_hide_completed -> {
menuItem.isChecked = !menuItem.isChecked
viewModel.onHideCompletedSelected(menuItem.isChecked)
true
}
R.id.tasks_list_menu_delete_completed -> {
viewModel.onDeleteAllCompletedClick()
true
}
R.id.tasks_list_menu_delete_all -> {
viewModel.onDeleteAllClick()
true
}
else -> false
}
}
}, viewLifecycleOwner, Lifecycle.State.RESUMED)
}
interface ChildFragmentListener {
fun onFragmentChanged(menu: Menu)
}
fun setListener(listener: ChildFragmentListener) {
this.childFragmentListener = listener
}
override fun onItemClick(task: Task) {
viewModel.onTaskSelected(task)
}
override fun onItemLongClick(task: Task) {
viewModel.onTaskLongSelected(task)
}
override fun onCheckboxClick(task: Task, isChecked: Boolean) {
viewModel.onTaskCheckedChanged(task, isChecked)
}
override fun onAttach(context: Context) {
super.onAttach(context)
childFragmentListener = context as ChildFragmentListener
}
override fun onPause() {
super.onPause()
Logger.i(TAG, "onPause", "TasksListFragment paused")
}
override fun onDestroyView() {
super.onDestroyView()
searchView.setOnQueryTextListener(null)
}
}
TodayFragment.kt
#ExperimentalCoroutinesApi
#AndroidEntryPoint
class TodayFragment : Fragment(R.layout.fragment_parent_today), TasksListFragment.ChildFragmentListener {
private val viewModel: TodayViewModel by viewModels()
private lateinit var binding: FragmentParentTodayBinding
private var fabClicked: Boolean = false
private lateinit var tasksListMenu: Menu
private lateinit var viewPager: ViewPager2
private val rotateOpen: Animation by lazy { AnimationUtils.loadAnimation(requireContext(), R.anim.rotate_open_anim) }
private val rotateClose: Animation by lazy { AnimationUtils.loadAnimation(requireContext(), R.anim.rotate_close_anim) }
private val fromBottom: Animation by lazy { AnimationUtils.loadAnimation(requireContext(), R.anim.from_bottom_anim) }
private val toBottom: Animation by lazy { AnimationUtils.loadAnimation(requireContext(), R.anim.to_bottom_anim) }
private val fadeIn: Animation by lazy { AnimationUtils.loadAnimation(requireContext(), R.anim.fade_in) }
private val fadeOut: Animation by lazy { AnimationUtils.loadAnimation(requireContext(), R.anim.fade_out) }
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
binding = FragmentParentTodayBinding.bind(view)
binding.apply {
tasksListTransparentWhiteScreen.setOnClickListener {
fabAnimationsRollBack(binding)
fabClicked = !fabClicked
}
}
setChildFragmentMenus()
initViewPagerWithTabLayout(binding)
todayDateDisplay(binding)
initFabs(binding)
loadTodayEventCollector()
getFragmentResultListeners()
}
private fun setChildFragmentMenus(){
val tasksListFragment = TasksListFragment()
tasksListFragment.setListener(this)
Logger.i(TAG, "setChildFragmentMenus", "TasksListFragment menu set")
}
private fun getFragmentResultListeners() {
setFragmentResultListener("add_edit_request"){_, bundle ->
val result = bundle.getInt("add_edit_result")
onFragmentResult(result)
}
setFragmentResultListener("create_set_request_2"){_, bundle ->
val result = bundle.getInt("create_set_result_2")
onFragmentResult(result)
}
setFragmentResultListener("task_added_to_set_request"){_, bundle ->
val result = bundle.getInt("task_added_to_set_result")
val message = bundle.getString("task_added_to_set_message")
onFragmentResult(result, message)
}
setFragmentResultListener("task_added_from_set_request"){_, bundle ->
val result = bundle.getInt("task_added_from_set_result")
val message = bundle.getString("task_added_from_set_message")
onFragmentResult(result, message)
}
}
private fun onFragmentResult(result: Int, message: String? = ""){
viewModel.onFragmentResult(result, message)
}
/**
* TodayViewModel.TodayEvent.NavigateToAddTaskScreen: Relevant to this class. Belongs to Fab which are all in this class.
* TodayViewModel.TodayEvent.ShowTaskSavedConfirmationMessage: Relevant to this class. Belongs to onFragmentResultListener which is here.
* TodayViewModel.TodayEvent.ShowTaskSavedInNewOrOldSetConfirmationMessage: Relevant to this class. Belongs to onFragmentResultListener which is here.
* TodayViewModel.TodayEvent.ShowTaskAddedFromSetConfirmationMessage: Relevant to this class. Belongs to onFragmentResultListener which is here.
* TodayViewModel.TodayEvent.NavigateToAddTasksFromSetBottomSheet: Relevant to this class. Belongs to Fab which are all in this class.
*/
private fun loadTodayEventCollector() {
viewLifecycleOwner.lifecycleScope.launchWhenStarted {
viewModel.todayEvent.collect { event ->
when (event) {
is TodayViewModel.TodayEvent.NavigateToAddTaskScreen -> {
val action = TodayFragmentDirections
.actionTodayFragmentToTaskAddEditFragment(task = null, title = "Add task"
, taskinset = null, origin = 1)
findNavController().navigate(action)
}
is TodayViewModel.TodayEvent.ShowTaskSavedConfirmationMessage -> {
Snackbar.make(requireView(), event.msg, Snackbar.LENGTH_LONG).show()
setViewPagerPage(0)
}
is TodayViewModel.TodayEvent.ShowTaskSavedInNewOrOldSetConfirmationMessage -> {
Snackbar.make(requireView(), event.msg.toString(), Snackbar.LENGTH_LONG).show()
}
is TodayViewModel.TodayEvent.ShowTaskAddedFromSetConfirmationMessage -> {
Snackbar.make(requireView(), event.msg.toString(), Snackbar.LENGTH_LONG).show()
fabClicked = true
setFabAnimationsAndViewStates(binding)
setViewPagerPage(0)
}
is TodayViewModel.TodayEvent.NavigateToAddTasksFromSetBottomSheet -> {
val action = TasksListFragmentDirections
.actionGlobalSetBottomSheetDialogFragment(task = null, origin = 2)
findNavController().navigate(action)
}
}.exhaustive
}
}
}
// This will soon be used to be 1
private fun setViewPagerPage(index: Int){
viewModel.postActionWithDelay(300, object: TodayViewModel.PostActionListener{
override fun onDelayFinished() {
viewPager.setCurrentItem(index, true)
}
})
}
private fun todayDateDisplay(binding: FragmentParentTodayBinding) {
binding.apply {
tasksListDateheader.apply {
dateHeaderDayofmonth.text = viewModel.getCurrentDayOfMonth()
dateHeaderMonth.text = viewModel.getCurrentMonth()
dateHeaderYear.text = viewModel.getCurrentYear()
dateHeaderDayofweek.text = viewModel.getCurrentDayOfWeek()
}
}
}
private fun initViewPagerWithTabLayout(binding: FragmentParentTodayBinding) {
viewPager = binding.todayViewpager
val tabLayout: TabLayout = binding.todayTablayout
viewPager.adapter = activity?.let { TodayPagerAdapter(it) }
Logger.i(TAG, "initViewPagerWithTabLayout", "viewPager is not null")
TabLayoutMediator(tabLayout, viewPager) { tab, index ->
tab.text = when (index) {
0 -> "Tasks"
1 -> "Journal"
else -> throw Resources.NotFoundException("Tab not found at position")
}.exhaustive
when (index) {
0 -> {
}
1 -> {
fabClicked = false
}
}
}.attach()
}
private fun initFabs(binding: FragmentParentTodayBinding) {
binding.apply {
tasksListFab.setOnClickListener {
onMainFabClick(binding)
}
tasksListSubFab1.setOnClickListener {
Logger.i(TAG, "initFabs", "Coming soon")
}
tasksListSubFab2.setOnClickListener {
viewModel.onAddTasksFromSetClick()
}
tasksListSubFab3.setOnClickListener {
viewModel.onAddNewTaskClick()
}
}
}
private fun onMainFabClick(binding: FragmentParentTodayBinding) {
setFabAnimationsAndViewStates(binding)
}
private fun setFabAnimationsAndViewStates(binding: FragmentParentTodayBinding) {
setFabAnimationVisibilityAndClickability(binding, fabClicked)
fabClicked = !fabClicked
}
private fun setFabAnimationVisibilityAndClickability(binding: FragmentParentTodayBinding, clicked: Boolean) {
if (!clicked) fabAnimationsRollIn(binding) else fabAnimationsRollBack(binding)
}
private fun fabAnimationsRollIn(binding: FragmentParentTodayBinding) {
binding.apply {
HGDAAnimationUtils.apply {
HGDAViewStateUtils.apply {
setViewAnimation(v1 = tasksListFab, a = rotateOpen)
setViewAnimation(v1 = tasksListSubFab1, v2 = tasksListSubFab2, v3 = tasksListSubFab3, a = fromBottom)
setViewAnimation(v1 = tasksListSubFab1Tv, v2 = tasksListSubFab2Tv, v3 = tasksListSubFab3Tv, a = fromBottom)
setViewAnimation(v1 = tasksListTransparentWhiteScreen, a = fadeIn)
setViewVisibility(v1 = tasksListSubFab1, v2 = tasksListSubFab2, v3 = tasksListSubFab3
, v4 = tasksListSubFab1Tv, v5 = tasksListSubFab2Tv, v6 = tasksListSubFab3Tv, visibility = View.VISIBLE)
setViewVisibility(v1 = tasksListTransparentWhiteScreen, visibility = View.VISIBLE)
setViewClickState(v1 = tasksListSubFab1, v2 = tasksListSubFab2, v3 = tasksListSubFab3, clickable = true)
setViewClickState(v1 = tasksListTransparentWhiteScreen, clickable = true)
}
}
}
}
private fun fabAnimationsRollBack(binding: FragmentParentTodayBinding) {
binding.apply {
HGDAAnimationUtils.apply {
HGDAViewStateUtils.apply {
setViewAnimation(v1 = tasksListFab, a = rotateClose)
setViewAnimation(v1 = tasksListSubFab1, v2 = tasksListSubFab2, v3 = tasksListSubFab3, a = toBottom)
setViewAnimation(v1 = tasksListSubFab1Tv, v2 = tasksListSubFab2Tv, v3 = tasksListSubFab3Tv, a = toBottom)
setViewAnimation(v1 = tasksListTransparentWhiteScreen, a = fadeOut)
setViewVisibility(v1 = tasksListSubFab1, v2 = tasksListSubFab2, v3 = tasksListSubFab3
, v4 = tasksListSubFab1Tv, v5 = tasksListSubFab2Tv, v6 = tasksListSubFab3Tv, visibility = View.INVISIBLE)
setViewVisibility(v1 = tasksListTransparentWhiteScreen, visibility = View.INVISIBLE)
setViewClickState(v1 = tasksListSubFab1, v2 = tasksListSubFab2, v3 = tasksListSubFab3, clickable = false)
setViewClickState(v1 = tasksListTransparentWhiteScreen, clickable = false)
}
}
}
}
override fun onFragmentChanged(menu: Menu) {
tasksListMenu = menu
}
override fun onPause() {
super.onPause()
tasksListMenu.clear()
}
}

Fragment is not a Context i.e fragment is not a child of context .
So when you try to cast context as ChildFragmentListener you are actually casting your Activity to ChildFragmentListener which is giving you this RuntimeException . to make it work you can use childFragmentListener = parentFragment as ChildFragmentListener
Also if your Doing this you do not need setListener method anymore.
On other hand i would suggest you do not use listeners to communicate b/w fragments . I see you already using viewModel so just use a shared one to communicate . You can get a shared ViewModel inside child by creating it with parentFragment.

Handle search results after configuration change MVVM

I am building a movie app based on "The Movie DB". My app has only one activity with a recyclerview and one search action button (SearchView).
As soon as the app starts,the recyclerview filled with popularMovies list.
When I search for a movie I get the results and everything is fine,but when I rotate the screen I get the popularMovies list and not my search results.
Now I know the reason,its happening because in onCreate I have initMoviesRecyclerView() that fill the recyclerview with popularMovies.
My question is how can I keep the search results without filling the recyclerview with popularMovies ? How can I do this the correct way ?
This is the Repository Class:
class MainRepository {
//MutableLiveData
private val popularMoviesMutableLiveData = MutableLiveData<List<Movie>>()
private val searchAfterMutableLiveData = MutableLiveData<List<Movie>>()
// API
private val apiService : GetFromApi = APIService.retrofitClientRequest
private val apiKey = "NOT"
fun getPopularMoviesList() : MutableLiveData<List<Movie>>{
apiService.getPopularMovies(apiKey,1)?.enqueue(object : Callback<MovieListResult?> {
override fun onResponse(
call: Call<MovieListResult?>,
response: Response<MovieListResult?>
) {
if (response.isSuccessful){
popularMoviesMutableLiveData.value = response.body()?.moviesResults
Log.e("MovieListResults","Result: ${popularMoviesMutableLiveData.value}")
}
}
override fun onFailure(call: Call<MovieListResult?>, t: Throwable) {
Log.e("MovieListResults","Failed: ${t.message}")
}
})
return popularMoviesMutableLiveData
}
fun searchAfter(searchAfter : String) : MutableLiveData<List<Movie>>{
apiService.searchAfter(apiKey,searchAfter)?.enqueue(object : Callback<MovieListResult?> {
override fun onResponse(
call: Call<MovieListResult?>,
response: Response<MovieListResult?>
) {
if (response.isSuccessful){
searchAfterMutableLiveData.value = response.body()?.moviesResults
Log.e("SearchMovieListResults","Result: ${searchAfterMutableLiveData.value}")
}
}
override fun onFailure(call: Call<MovieListResult?>, t: Throwable) {
Log.e("SearchMovieListResults","Failed: ${t.message}")
}
})
return searchAfterMutableLiveData
}
}
This is the viewModel class:
class MainViewModel : ViewModel(){
//Repository
private val mainRepository = MainRepository()
//MutableLiveData
var popularMoviesMutableLiveData = MutableLiveData<List<Movie>>()
var searchAfterMutableLiveData = MutableLiveData<List<Movie>>()
//The Main Movie List
var mainMovieList = listOf<Movie>()
fun getPopularMovies() : LiveData<List<Movie>>{
popularMoviesMutableLiveData = mainRepository.getPopularMoviesList()
popularMoviesMutableLiveData.value = mainMovieList
return popularMoviesMutableLiveData
}
fun getMovieBySearch(searchAfter : String) : LiveData<List<Movie>>{
searchAfterMutableLiveData = mainRepository.searchAfter(searchAfter)
searchAfterMutableLiveData.value = mainMovieList
return searchAfterMutableLiveData
}
}
This is the MainActivity class:
class MainActivity : AppCompatActivity() {
//ViewModel
private val mainViewModel : MainViewModel by viewModels()
// Views
private lateinit var mainRecyclerView : RecyclerView
private lateinit var mainAdapter : MainRecyclerViewAdapter
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
initMoviesRecyclerView()
}
private fun initMoviesRecyclerView() {
mainRecyclerView = findViewById(R.id.mainRecyclerView)
mainRecyclerView.setHasFixedSize(true)
mainRecyclerView.layoutManager = GridLayoutManager(this,1)
mainViewModel.getPopularMovies().observe(this, object : Observer<List<Movie>?> {
override fun onChanged(newList: List<Movie>?) {
if (newList != null) {
mainViewModel.mainMovieList = newList
mainAdapter = MainRecyclerViewAdapter(mainViewModel.mainMovieList)
mainRecyclerView.adapter = mainAdapter
}
}
})
}
override fun onCreateOptionsMenu(menu: Menu): Boolean {
menuInflater.inflate(R.menu.main_menu,menu)
val searchView = menu.findItem(R.id.menu_search_movie).actionView as androidx.appcompat.widget.SearchView
searchView.queryHint = "Search By Name,Actor .."
searchView.setOnQueryTextListener(object : androidx.appcompat.widget.SearchView.OnQueryTextListener {
override fun onQueryTextSubmit(whileTextChange: String?): Boolean {
//Clear SearchView
searchView.isIconified = true
searchView.setQuery("", false)
searchView.onActionViewCollapsed()
mainViewModel.getMovieBySearch(whileTextChange.toString()).observe(this#MainActivity,object : Observer<List<Movie>?> {
override fun onChanged(newList: List<Movie>?) {
if (newList != null) {
mainViewModel.mainMovieList = newList
mainAdapter.changeCurrentList(mainViewModel.mainMovieList)
}
}
})
return false
}
override fun onQueryTextChange(whileTextChange: String?): Boolean {
Log.e("onQueryTextChange","Text: $whileTextChange")
return false
}
})
return true
}
}
Thank you!

I don't see where you actually populate the data inside the ViewModel. But it all looked good.
This line is a bit suspicious:
mainViewModel.mainMovieList = newList
You should not update the ViewModel from the View lifeCycle. Also, you should not update the ViewModel during the observe call.

So after sometime I manage to work around it with a simple solution:
I created a function in the viewModel,to check if the search list value is null:
fun startFromSearch(): Boolean {
return searchAfterMutableLiveData.value != null
}
After that I made an if statement in the initMoviesRecyclerView(), and that's it!
private fun initMoviesRecyclerView() {
mainRecyclerView = findViewById(R.id.mainRecyclerView)
mainRecyclerView.setHasFixedSize(true)
mainRecyclerView.layoutManager = GridLayoutManager(this,1)
mainAdapter = MainRecyclerViewAdapter(mainViewModel.mainMovieList,this)
mainRecyclerView.adapter = mainAdapter
if (!mainViewModel.startFromSearch()){
mainViewModel.getPopularMovies(1).observe(this, object : Observer<List<Movie>?> {
override fun onChanged(newList: List<Movie>?) {
if (newList != null) {
mainAdapter = MainRecyclerViewAdapter(newList,this#MainActivity)
mainRecyclerView.adapter = mainAdapter
}
}
})
}
}

The buttons of my introSlider aren't working, why is this happening - question Updated

I'm trying to build an app that has an intro slider when it's installed. I followed a tutorial.
However, I have an error and the app doesn't even open.
Here is some code:
Class Intro
class Intro : AppCompatActivity(), View.OnClickListener {
lateinit var mPager : ViewPager
var layouts : IntArray = intArrayOf(R.layout.first_slide,R.layout.second_slide,R.layout.third_slide)
lateinit var dotsLayout : LinearLayout
lateinit var dots: Array<ImageView>
lateinit var mAdapter : PageAdapter
lateinit var btnNext: Button
lateinit var btnSkip: Button
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_intro)
if(PrefManager(this).checkPreferences()){goToHomePage()}
if(Build.VERSION.SDK_INT >=19)
{
window.addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS)
}else{
window.clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS)
}
mPager=findViewById(R.id.pager)
mAdapter= PageAdapter(layouts,this)
mPager.adapter= mAdapter
dotsLayout = findViewById(R.id.dots)
btnNext = findViewById(R.id.btnNext)
btnSkip=findViewById(R.id.btnSkip)
btnSkip.setOnClickListener { this }
btnNext.setOnClickListener { this }
createDots(0)
mPager.addOnPageChangeListener(object : ViewPager.OnPageChangeListener{
override fun onPageScrollStateChanged(state: Int) {
}
override fun onPageScrolled(
position: Int,
positionOffset: Float,
positionOffsetPixels: Int
) {
}
override fun onPageSelected(position: Int) {
createDots(position)
if(position == layouts.size){
btnNext.setText("DONE")
btnSkip.visibility=View.INVISIBLE
}else{
btnNext.setText("NEXT")
btnSkip.visibility=View.VISIBLE
}
}
})
}
fun createDots(position:Int){
if(dotsLayout!=null){
dotsLayout.removeAllViews()
}
dots = Array(layouts.size,{i -> ImageView(this)})
for(i in 0..layouts.size -1) {
dots[i] = ImageView(this)
if (i == position) {
dots[i].setImageDrawable(ContextCompat.getDrawable(this, R.drawable.active_dots))
} else {
dots[i].setImageDrawable(ContextCompat.getDrawable(this, R.drawable.inactive_dots))
}
var params: LinearLayout.LayoutParams = LinearLayout.LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT
)
params.setMargins(4,0,4,0)
dotsLayout.addView(dots[i],params)
}
}
override fun onClick(v: View?) {
when(v!!.id){
R.id.btnSkip ->{
goToHomePage()
PrefManager(this).writeSharedPreferences()
}
R.id.btnNext ->{
loadNextSlide()
}
}
}
private fun goToHomePage() {
startActivity(Intent(this, HomePage::class.java))
finish()
}
private fun loadNextSlide() {
var nextSlide: Int = mPager.currentItem+1
if(nextSlide<layouts.size){
mPager.setCurrentItem(nextSlide)
}
else{
goToHomePage()
PrefManager(this).writeSharedPreferences()
}
}
}
Class PrefManager
class PrefManager {
lateinit var context : Context
lateinit var pref: SharedPreferences
constructor(context: Context) {
this.context = context
getSharedPreferences()
}
private fun getSharedPreferences(){
pref = context.getSharedPreferences(context.getString(R.string.pref_name), Context.MODE_PRIVATE)
}
fun writeSharedPreferences(){
var editor : SharedPreferences.Editor=pref.edit()
editor.putString(context.getString(R.string.pref_key),"NEXT")
editor.commit()
}
fun checkPreferences() : Boolean
{
var status: Boolean = false
status = !pref.getString(context.getString(R.string.pref_key),null).equals("null")
return status
}
fun clearPreferences(){
pref.edit().clear().commit()
context.startActivity(Intent(context, HomePage::class.java))
(context as AppCompatActivity).finish()
}
}
The app works but the buttons next and skip don't respond whe clicked. Why is this happening?
Update: I changed some redundant thing on the code and uncommented the part that I've previous commented, and I don't have the error anymore. But the buttons still don't work

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

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()