I'm using recyclerView to display my data but anything is displaying. The onBindViewHolder is never called and the onCreateViewHolder also.
I initialize the adapter in the viewModel with the data which I got from room but anything is displaying. The data in the viewModel is there when I want give it to the adaptater.
There's the adaptater,
class CountryInfoAdapter : RecyclerView.Adapter<TextItemViewHolder>() {
var data = listOf<DevByteCountryProperty>()
set(value) {
field = value
notifyDataSetChanged()
}
override fun getItemCount() = data.size
override fun onBindViewHolder(holder: TextItemViewHolder, position: Int) {
val item = data[position]
holder.textView.text = item.name.toString()
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): TextItemViewHolder {
//The inflater knows how to create views from XML layout. The context is the context of the RecyclerView.
val layoutInflater = LayoutInflater.from(parent.context)
val view = layoutInflater.inflate(R.layout.text_item_view, parent, false) as TextView
Timber.i("Data from adaptater : ${data.toString()}")
return TextItemViewHolder(view)
}
}
There is the Fragment,
class CountryInfoFragment : Fragment() {
private lateinit var viewModel: CountryInfoViewModel
private lateinit var viewModelFactory: CountryInfoViewModelFactory
private lateinit var binding: FragmentCountryInfoBinding
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
binding = DataBindingUtil.inflate(inflater,
R.layout.fragment_country_info,container,false)
val application = requireNotNull(this.activity).application
viewModelFactory = CountryInfoViewModelFactory(application)
viewModel = ViewModelProvider(this,viewModelFactory).get(CountryInfoViewModel::class.java)
binding.viewModel = viewModel
val adapter = CountryInfoAdapter()
viewModel.countriesProperty.observe(viewLifecycleOwner, Observer {
it?.let {
adapter.data = it
}
})
binding.countryList.adapter = adapter
binding.lifecycleOwner = viewLifecycleOwner
setHasOptionsMenu(true)
return binding.root
}
}
Please try below code, setting up layout manager before assigning adapter to recyclerView
binding.countryList.layoutManager = LinearLayoutManager(this)
binding.countryList.adapter = adapter
Related
I am working on a simple project. I am trying to show list of data but in adapter none of the methods are called
class PlacnikiAdapter(private val placniki: List<Placnik>) :
RecyclerView.Adapter<PlacnikiAdapter.ViewHolder>() {
class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
val textView: TextView
init {
// Define click listener for the ViewHolder's View.
textView = view.findViewById(R.id.ime)
}
}
override fun onCreateViewHolder(viewGroup: ViewGroup, viewType: Int): ViewHolder {
val inflater = LayoutInflater.from(viewGroup.context).inflate(R.layout.layout_rv_item,
viewGroup, false)
return ViewHolder(inflater)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.textView.text = placniki[position].ime
}
override fun getItemCount(): Int {
return placniki.size
}
class PlacnikiFragment : Fragment() {
private val TAG = "PlacnikiFragment"
private lateinit var binding: PlacnikiFragmentBinding
lateinit var viewModel: MainViewModel
private val retrofitService = RetrofitService.getInstance()
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Defines the xml file for the fragment
return inflater.inflate(R.layout.placniki_fragment, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
binding = PlacnikiFragmentBinding.inflate(layoutInflater)
//get viewmodel instance using MyViewModelFactory
viewModel =
ViewModelProvider(this, ViewModelFactory(Repository(retrofitService))).get(
MainViewModel::class.java
)
//set recyclerview adapter
viewModel.placnikiList.observe(viewLifecycleOwner, {
Log.d(TAG, "placnikiList: $it")
binding.recyclerview.adapter = PlacnikiAdapter(it)
})
viewModel.errorMessage.observe(viewLifecycleOwner, {
Log.d(TAG, "errorMessage: $it")
})
viewModel.getVsiPlacniki()
}
I dont know what could be causing this. I changed activity to a fragment and beforehand everything worked normally and after changing to fragment recyclerview isnt showing items and the list isnt empty either so i dont pass list of zero items
I found the solution, the problem was in data binding. I had to add below code in gradle module
buildFeatures{dataBinding = true}
I am trying to work wih courutines and recycler view. I've done everything necessary to send requests to the API, but I still can't get the list that should be inside the recycler view. I am using fragment to create list and bottom nav. When I go to the fragment where my list should be, then I get the error: RecyclerView: No layout manager attached; skipping layoutand nothing more. I googled about this error and it says I should define the layout manager in xml, but it alreadt has layuout manager in my fragment
<androidx.recyclerview.widget.RecyclerView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/list_item"
app:layoutManager="LinearLayoutManager"
Also my adapter and fragment for recycler view look like this:
class MyItemRecyclerViewAdapter(
) : RecyclerView.Adapter<MyItemRecyclerViewAdapter.ViewHolder>() {
var userNameResponse = mutableListOf<UsersNameItem>()
fun setNamesList(names: List<UsersNameItem>) {
this.userNameResponse = userNameResponse.toMutableList()
notifyDataSetChanged()
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
return ViewHolder(
FragmentItemBinding.inflate(
LayoutInflater.from(parent.context),
parent,
false
)
)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
val item = userNameResponse[position]
holder.idView.text = item.id
holder.contentView.text = item.name
}
override fun getItemCount(): Int = userNameResponse.size
class ViewHolder(binding: FragmentItemBinding) : RecyclerView.ViewHolder(binding.root) {
val idView: TextView = binding.itemNumber
val contentView: TextView = binding.content
}
}
Fragment:
class ItemFragment : Fragment() {
private var layoutManager: RecyclerView.LayoutManager? = null
private var adapter: RecyclerView.Adapter<MyItemRecyclerViewAdapter.ViewHolder>? = null
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_item_list, container, false)
}
override fun onViewCreated(itemView: View, savedInstanceState: Bundle?) {
super.onViewCreated(itemView, savedInstanceState)
layoutInflater.apply {
layoutManager = LinearLayoutManager(activity)
adapter = MyItemRecyclerViewAdapter()
}
}
companion object {
fun newInstance() = ItemFragment()
}
}
And MainActivity where I set up courutines and trying to make a request:
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
lateinit var nameviewModel: ListNamesViewModel
val adapter = MyItemRecyclerViewAdapter()
///trying to create http-request for lists
val retrofitService = BasicApiService.getInstance()
val mainRepository = MainRepository(retrofitService)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
nameviewModel = ViewModelProvider(
this,
MyViewModelFactory(mainRepository)
)[ListNamesViewModel::class.java]
nameviewModel.userName.observe(
this, Observer {
adapter.setNamesList(it)
})
nameviewModel.message.observe(this) {
Toast.makeText(this, it, Toast.LENGTH_SHORT).show()
}
nameviewModel.loadUsers()
val navView: BottomNavigationView = binding.navView
val navController = findNavController(R.id.nav_host_fragment_activity_main)
val appBarConfiguration = AppBarConfiguration(
setOf(
R.id.navigation_home,
R.id.navigation_dashboard,
R.id.navigation_notifications,
R.id.list_name_navig
)
)
setupActionBarWithNavController(navController, appBarConfiguration)
navView.setupWithNavController(navController)
}
}
Also I wanted to ask (I am very new to Kotlin nad just trying to make things work) if it is a good practice to leave request to API in the MainActivity ot I should do it in another way?
I see some confusion in your code, try to apply the next:
Why are you creating the layoutManager and adapter in the ItemFragment?
override fun onViewCreated(itemView: View, savedInstanceState: Bundle?) {
super.onViewCreated(itemView, savedInstanceState)
layoutInflater.apply {
layoutManager = LinearLayoutManager(activity)
adapter = MyItemRecyclerViewAdapter()
}
}
You need to move it and RecyclerView to your activity.
The using layoutInflater.apply {} doesn't make sense, it's doing nothing in your case. You need to set layoutManager and adapter to recyclerView then in the activity it should look like that (and rename list_item to recyclerView)
binding.recyclerView.apply {
layoutManager = LinearLayoutManager(this)
adapter = MyItemRecyclerViewAdapter()
}
Remove app:layoutManager="LinearLayoutManager" from XML.
It looks like you don't need to use ItemFragment for your purpose because you use it just like a view and binding in the ViewHolder
class ViewHolder(binding: FragmentItemBinding) : RecyclerView.ViewHolder(binding.root) {
val idView: TextView = binding.itemNumber
val contentView: TextView = binding.content
}
try changing in xml
app:layoutManager="LinearLayoutManager"
to
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
I am making a simple application. There are 2 screens in the application: List screen, Add screen.
Scenario: When the application is opened, there is a list page on the screen. The user goes to the Adding page with the help of the Floating Action Button on the list page. Here, he enters the items with the help of Edit Text and comes to the List page by pressing the Add Button.
I am using MVVM in this application and I am a beginner. So I can't find the problem. Here is the problem: I am adding new elements to my list in the Add Fragment, but these elements are not seems in the List Fragment.
Thanks in advance.
Model Class
data class Movie(
val movieName: String,
val releaseDate: String
)
ViewModel class
class MovieViewModel : ViewModel() {
val movies = MutableLiveData<ArrayList<Movie>>()
var movieList = arrayListOf<Movie>()
fun addMovie(movie: Movie) {
movieList.add(movie)
movies.value = movieList
}
}
Adapter Class
class MovieAdapter : RecyclerView.Adapter<MovieAdapter.MyViewHolder>() {
private var movieList = emptyList<Movie>()
class MyViewHolder(private val binding: RowItemBinding) :
RecyclerView.ViewHolder(binding.root) {
fun bind(movie: Movie) {
binding.textViewMovieName.text = movie.movieName
binding.textViewReleaseDate.text = movie.releaseDate
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
val layoutInflater = LayoutInflater.from(parent.context)
val binding = RowItemBinding.inflate(layoutInflater, parent, false)
return MyViewHolder(binding)
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
val currentItem = movieList[position]
holder.bind(currentItem)
}
override fun getItemCount(): Int {
return movieList.size
}
fun setData(movie: List<Movie>) {
val movieDiffUtil = MovieDiffUtil(movieList, movie)
val movieDiffResult = DiffUtil.calculateDiff(movieDiffUtil)
this.movieList = movie
movieDiffResult.dispatchUpdatesTo(this)
}
}
Add Fragment
class AddFragment : Fragment() {
private var _binding: FragmentAddBinding? = null
private val binding get() = _binding!!
private val movieViewModel: MovieViewModel by viewModels<MovieViewModel>()
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
_binding = FragmentAddBinding.inflate(inflater, container, false)
binding.buttonAdd.setOnClickListener {
insertData()
}
return binding.root
}
private fun insertData() {
val movieName = binding.editTextMovieName.text.toString()
val releaseDate = binding.editTextReleaseDate.text.toString()
val movie = Movie(movieName, releaseDate)
movieViewModel.addMovie(movie)
findNavController().navigate(R.id.action_addFragment_to_listFragment)
}
override fun onDestroyView() {
super.onDestroyView()
_binding = null
}
}
List Fragment
class ListFragment : Fragment() {
private var _binding: FragmentListBinding? = null
private val binding get() = _binding!!
private val adapter: MovieAdapter by lazy { MovieAdapter() }
private val movieViewModel: MovieViewModel by viewModels<MovieViewModel>()
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
_binding = FragmentListBinding.inflate(inflater, container, false)
setAdapter()
movieViewModel.movies.observe(viewLifecycleOwner, { data ->
adapter.setData(data)
binding.textView.setText(data.get(0).movieName)
})
binding.floatingActionButton.setOnClickListener {
findNavController().navigate(R.id.action_listFragment_to_addFragment)
}
return binding.root
}
private fun setAdapter() {
val recyclerView = binding.recyclerView
recyclerView.adapter = adapter
recyclerView.layoutManager = LinearLayoutManager(requireActivity())
}
override fun onDestroyView() {
super.onDestroyView()
_binding = null
}
}
After adding an item to a List<> you need to notify the Adapter that the data has changed.
You can do so by calling adapter.notifyDataSetChanged().
I added my List directly into the Adapter but you can create a function like in the following stackoverflow post.
How to update my Recyclerview using kotlin android?
So I've been wrestling with this for days and I need some help. I've made this code work in an activity, but then I move it to a fragment it doesn't work. Everything else is the same between the two.
Using the debugger with the working Activity, the line
apiService = retrofit.create<HomeJsonApiService>(HomeJsonApiService::class.java)
goes to getItemCount(). However in the fragment it goes directly to onCreateView in the Fragment. I've attached my code below. Thanks in advance for the help! And be gentle. I'm still new to this :)
First is my fragment:
class TabHomeActivity : Fragment() {
val itemList = ArrayList<HomeCards>()
lateinit var adapter: HomeCardsAdapter
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
var binding = FragmentTabHomeActivityBinding.inflate(layoutInflater)
adapter = HomeCardsAdapter()
var rv = binding.rvHomeCards
rv.adapter = adapter
loadData()
}
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,savedInstanceState: Bundle?): View? {
return inflater.inflate(R.layout.cards_home, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
}
private fun loadData() {
ApiManager.getInstance().service.listHeroes()
.enqueue(object : Callback<ResponseData<List<HomeCards>>> {
override fun onResponse(
call: Call<ResponseData<List<HomeCards>>>,
response: Response<ResponseData<List<HomeCards>>>
) {
val listData: List<HomeCards> = response.body()!!.data
// updating data from network to adapter
itemList.clear()
itemList.addAll(listData)
adapter.updateData(itemList)
adapter.notifyDataSetChanged()
}
override fun onFailure(call: Call<ResponseData<List<HomeCards>>>, t: Throwable) {
}
})
}
}
The HTTP request:
data class ResponseData<T> (
val code: Int,
val data: T
)
interface HomeJsonApiService {
#GET("marvel-heroes.asp?h=2")
fun listHeroes(): retrofit2.Call<ResponseData<List<HomeCards>>>
}
class ApiManager {
private var apiService: HomeJsonApiService? = null
init {
createService()
}
val service: HomeJsonApiService get() = apiService!!
private fun createService() {
val loggingInterceptor =
HttpLoggingInterceptor(object : HttpLoggingInterceptor.Logger {
override fun log(message: String) {
Log.i("Retrofit", message)
}
})
loggingInterceptor.level = HttpLoggingInterceptor.Level.BODY
val client = OkHttpClient.Builder()
.readTimeout(30, TimeUnit.SECONDS)
.connectTimeout(30, TimeUnit.SECONDS)
.writeTimeout(30, TimeUnit.SECONDS)
.addInterceptor(loggingInterceptor)
.build()
val retrofit: Retrofit = Retrofit.Builder()
.client(client)
.baseUrl("https://www.mywebsite.com/jsonfolder/JSON/")
.addConverterFactory(GsonConverterFactory.create())
.build()
apiService = retrofit.create(HomeJsonApiService::class.java)
}
companion object {
private var instance: ApiManager? = null
fun getInstance(): ApiManager {
return instance ?: synchronized(this) {
ApiManager().also { instance = it }
}
}
}
}
And my adapter:
class HomeCardsAdapter() : RecyclerView.Adapter<HomeCardsAdapter.ViewHolder>() {
private lateinit var itemList: List<HomeCards>
lateinit var context: Context
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
context = parent.context
val view = LayoutInflater.from(context).inflate(R.layout.cards_home, parent, false)
return ViewHolder(view)
}
override fun getItemCount(): Int {
return if (::itemList.isInitialized) itemList.size else 0
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.bind()
}
fun updateData(list: List<HomeCards>) {
itemList = list;
notifyDataSetChanged()
}
inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
//var binding = ActivityMainBinding(layoutInflater(inf))
fun bind() {
val item = itemList.get(adapterPosition)
ViewHolder(itemView).itemView.findViewById<TextView>(R.id.cardHomeTitle).text = item.name
ViewHolder(itemView).itemView.findViewById<TextView>(R.id.cardHomeTitle).text = item.superheroName
Glide.with(context)
.load(item.photo)
.diskCacheStrategy(DiskCacheStrategy.ALL)
.circleCrop()
.into(ViewHolder(itemView).itemView.findViewById<ImageView>(R.id.cardHomeIcon))
}
}
}
class HomeCards {
#SerializedName("superhero_name")
var superheroName: String = ""
var name: String = ""
var photo: String = ""
}
The main problem is:
var binding = FragmentTabHomeActivityBinding.inflate(layoutInflater)
That is inside on onCreate but onCreateView is returning another view inflater.inflate(R.layout.cards_home, container, false)
So you are applying the adapter to a recycler that is on the binding, but the view on the screen is inflated from the layout. Change it to this:
private lateinit var binding: FragmentTabHomeActivityBinding
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,savedInstanceState: Bundle?): View? {
binding = FragmentTabHomeActivityBinding.inflate(layoutInflater, container, false)
return binding.root
}
And move the code from from onCreate to onViewCreated but make sure to use the lateinit binding
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
adapter = HomeCardsAdapter()
var rv = binding.rvHomeCards
rv.adapter = adapter
loadData()
}
After that there is a problem in your adapter: private lateinit var itemList: List<HomeCards> very specifically List<HomeCards>. The method notifyDataSetChanged doesn't work by changing or updating the reference of the data structure but when the collection is modified. Change it to this:
private val list = mutableListOf<HomeCards>()
override fun getItemCount(): Int {
return list.size()
}
fun updateData(list: List<HomeCards>) {
this.itemList.clear()
this.itemList.addAll(list)
notifyDataSetChanged()
}
If onResponse() gets called and provides response, verify that code updating UI is running on main/ui thread. Common source of issue when working with network (other threads).
activity?.runOnUiThread {
itemList.clear()
itemList.addAll(listData)
adapter.updateData(itemList)
adapter.notifyDataSetChanged()
}
The problem is related to the fact that I don't manage to implement a OnItemClick listener for a RecyclerView that is located in a "mainFragment" by implementing the OnClickListener in the Adapter.
I would like my application (kotlin) to launch another fragment ("deletePage" in the code bellow) everytime an itemView (an ImageView) from the RecyclerView is clicked, this fragment would display the same photo in big.
My Adapter code is the following one:
class MyAdapter : RecyclerView.Adapter<MyAdapter.MyViewHolder>() {
private var photo = emptyList<Photo>()
inner class MyViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView)
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
return MyViewHolder(
LayoutInflater.from(parent.context).inflate(R.layout.row_layout, parent, false)
)
}
override fun getItemCount(): Int {
return photo.size
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
holder.itemView.longitude.text = photo[position].latitude
holder.itemView.latitude.text = photo[position].longitude
holder.itemView.imageView.load(photo[position].photo)
}
fun setData(photo: List<Photo>) {
this.photo = photo
notifyDataSetChanged()
}
}
And my mainFragment code is the following one:
class MainFragment : Fragment(){
private lateinit var myView: MyViewModel
private val adapter by lazy { MyAdapter() }
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
val view = inflater.inflate(R.layout.fragment_main, container, false)
//Recyclerview
val adapter = MyAdapter()
val recyclerView = view.recycler_view
recyclerView.adapter = adapter
recyclerView.layoutManager = LinearLayoutManager(requireContext())
myView = ViewModelProvider(this).get(MyViewModel::class.java)
myView.readPhoto.observe(viewLifecycleOwner, Observer {photo ->
adapter.setData(photo)
})
setHasOptionsMenu(true)
return view
}
override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
inflater.inflate(R.menu.menu_database, menu)
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
when {
item.itemId == R.id.deleteAll -> findNavController().navigate(R.id.deletePage)
item.itemId == R.id.refresh -> {
Toast.makeText(activity, "yep", Toast.LENGTH_SHORT).show()
instertDataToDatabase()
}
}
if (item.itemId == R.id.deleteAll) {
}
return super.onOptionsItemSelected(item)
}
}
The objective is that when you click on an item of the RecyclerView the "findNavController().navigate(R.id.deletePage)" fragment is displayed but everytime I try to implement a solution the application crashes when clicking at an item of the RecyclerView. Right now the navigation works by the click on a button in the Menu at the toolbar but is not the ideal solution.
Any sort of help or advice would be very much appreciated!
Firstly you need to give click listener of your itemView in onBindViewHolder
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
holder.itemView.longitude.text = photo[position].latitude
holder.itemView.latitude.text = photo[position].longitude
holder.itemView.imageView.load(photo[position].photo)
holder.itemView.setOnClickListener { navigateToFragment() }
}
For the navigation somehow you should have a context instance.
Here is the possible solutions that came up to my mind:
Give navigator instance to adapter
class Navigator(fragment: Fragment) {
private val fragmentRef = WeakReference(fragment)
fun navigate(){
// make your navigations here with using fragmentRef.get()
}
}
In your fragment:
private val navigator = Navigator(this)
...
val adapter = MyAdapter(navigator)
In your adapter:
class MyAdapter(private val navigator: Navigator) : RecyclerView.Adapter<MyAdapter.MyViewHolder>() {
fun navigateToFragment(){
navigator.navigate()
}
Make interface for callback
2.1. Implement that interface in fragment and give adapter the interface instance
interface Navigable{
fun navigate()
}
In your fragment:
class MainFragment : Fragment(), Navigable{
...
override fun navigate(){
// make your navigation
}
val adapter = MyAdapter(navigator)
In your adapter:
class MyAdapter(private val navigable: Navigable) : RecyclerView.Adapter<MyAdapter.MyViewHolder>() {
fun navigateToFragment(){
navigable.navigate()
}
2.2. Make the interface, but do not pass reference, use findFragment in adapter
In your adapter: override onAttachedToRecyclerView to find fragment
private lateinit var navigable: Navigable
override fun onAttachedToRecyclerView(recyclerView: RecyclerView) {
super.onAttachedToRecyclerView(recyclerView)
navigable = recyclerView.findFragment<Fragment>() as Navigable
}
fun navigateToFragment(){
navigable.navigate()
}