Develop Reference

onResume does not worked in viewmodel

my data is fetched only when it is created...im using viewmodel...when press back button it doesnt update the previous data..onresume is not working in this...
i refered this but none of those helped--> Reacting to activity lifecycle in ViewModel
i need help
thanks in advance
activity:--
class MyAccount : BaseClassActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.myaccount)
var mActionBarToolbar = findViewById<androidx.appcompat.widget.Toolbar>(R.id.toolbartable);
setSupportActionBar(mActionBarToolbar);
setEnabledTitle()
val resetbutton=findViewById<Button>(R.id.resetpwd)
resetbutton.setOnClickListener {
val i=Intent(applicationContext,
ResetPasswordActivity::class.java)
startActivity(i)
}
val editbutton=findViewById<Button>(R.id.editdetail)
editbutton.setOnClickListener {
val i=Intent(applicationContext, EditProfile::class.java)
startActivity(i)
}
hello()
}
override fun onResume() {
super.onResume()
hello()
}
fun hello(){
val first_name = findViewById<TextView>(R.id.firstname)
val last_name = findViewById<TextView>(R.id.lastname)
val emailuser = findViewById<TextView>(R.id.emailuser)
val phone_no = findViewById<TextView>(R.id.phone_no)
val birthday = findViewById<TextView>(R.id.birthday)
val image=findViewById<ImageView>(R.id.imageprofile)
val model = ViewModelProvider(this)[MyAccountViewModel::class.java]
model.viewmodel?.observe(this, object : Observer<My_account_base_response> {
override fun onChanged(t: My_account_base_response?) {
first_name.setText(t?.data?.user_data?.first_name)
last_name.setText(t?.data?.user_data?.last_name)
emailuser.setText(t?.data?.user_data?.email)
phone_no.setText(t?.data?.user_data?.phone_no).toString()
birthday.setText(t?.data?.user_data?.dob).toString()
Glide.with(applicationContext).load(t?.data?.user_data?.profile_pic)
.diskCacheStrategy(DiskCacheStrategy.ALL)
.placeholder(R.drawable.ic_launcher_foreground)
.into(image)
}
})
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
return when (item.itemId) {
android.R.id.home -> {
NavUtils.navigateUpFromSameTask(this)
true
}
else -> super.onOptionsItemSelected(item)
}
}}
viewmodel:--
class MyAccountViewModel(context: Application) :AndroidViewModel(context),LifecycleObserver{
private var MyAccountViewModels: MutableLiveData<My_account_base_response>? = null
val viewmodel: MutableLiveData<My_account_base_response>?
get() {
if (MyAccountViewModels == null) {
MyAccountViewModels = MutableLiveData<My_account_base_response>()
loadviewmodel()
}
return MyAccountViewModels
}
private fun loadviewmodel(){
val token :String = SharedPrefManager.getInstance(getApplication()).user.access_token.toString()
RetrofitClient.instance.fetchUser(token)
.enqueue(object : Callback<My_account_base_response> {
override fun onFailure(call: Call<My_account_base_response>, t: Throwable) {
Log.d("res", "" + t)
}
override fun onResponse(
call: Call<My_account_base_response>,
response: Response<My_account_base_response>
) {
var res = response
if (res.body()?.status == 200) {
MyAccountViewModels!!.value = response.body()
} else {
try {
val jObjError =
JSONObject(response.errorBody()!!.string())
Toast.makeText(getApplication(),
jObjError.getString("user_msg"),
Toast.LENGTH_LONG).show()
} catch (e: Exception) {
Log.e("errorrr", e.message)
}
}
}
})
}}

There are bunch of things wrong here, so let me provide you refactored code and explanation as much as I would be able to..
Activity:
class MyAccount : BaseClassActivity() {
private val mActionBarToolbar by lazy { findViewById<androidx.appcompat.widget.Toolbar>(R.id.toolbartable) }
private val resetbutton by lazy { findViewById<Button>(R.id.resetpwd) }
private val editbutton by lazy { findViewById<Button>(R.id.editdetail) }
private val first_name by lazy { findViewById<TextView>(R.id.firstname) }
private val last_name by lazy { findViewById<TextView>(R.id.lastname) }
private val emailuser by lazy { findViewById<TextView>(R.id.emailuser) }
private val phone_no by lazy { findViewById<TextView>(R.id.phone_no) }
private val birthday by lazy { findViewById<TextView>(R.id.birthday) }
private val image by lazy { findViewById<ImageView>(R.id.imageprofile) }
lateinit var model: MyAccountViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.myaccount)
setSupportActionBar(mActionBarToolbar)
setEnabledTitle()
model = ViewModelProvider(this)[MyAccountViewModel::class.java]
resetbutton.setOnClickListener {
val i = Intent(applicationContext, ResetPasswordActivity::class.java)
startActivity(i)
}
editbutton.setOnClickListener {
val i = Intent(applicationContext, EditProfile::class.java)
startActivity(i)
}
model.accountResponseData.observe(this, object : Observer<My_account_base_response> {
override fun onChanged(t: My_account_base_response?) {
first_name.setText(t?.data?.user_data?.first_name)
last_name.setText(t?.data?.user_data?.last_name)
emailuser.setText(t?.data?.user_data?.email)
phone_no.setText(t?.data?.user_data?.phone_no).toString()
birthday.setText(t?.data?.user_data?.dob).toString()
Glide.with(applicationContext)
.load(t?.data?.user_data?.profile_pic)
.diskCacheStrategy(DiskCacheStrategy.ALL)
.placeholder(R.drawable.ic_launcher_foreground)
.into(image)
}
})
}
override fun onResume() {
super.onResume()
model.loadAccountData()
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
return when (item.itemId) {
android.R.id.home -> {
NavUtils.navigateUpFromSameTask(this)
true
}
else -> super.onOptionsItemSelected(item)
}
}
}
Few notes on your activity class:
You don't need to findViewById everytime, just do it once during onCreate or do it lazily. (FYI consider using kotlin synthetics or view binding or data binding)
Initialize your viewModel during onCreate method only. (That's the best way to do it)
Also observer your LiveData from ViewModel once, it should be also from the onCreate as it's the entry point to the activity and apart from config changes this method called only once. So, it's safe to observe it over there rather than during onResume which will be called multiple times during activity lifecycle. (The main issue your code wasn't working, so as a fix you only call your API method from ViewModel during resume)
ViewModel:
class MyAccountViewModel(context: Application) : AndroidViewModel(context) {
private val _accountResponseData = MutableLiveData<My_account_base_response?>()
val accountResponseData: MutableLiveData<My_account_base_response?>
get() = _accountResponseData
init {
loadAccountData()
}
fun loadAccountData() {
val token: String = SharedPrefManager.getInstance(getApplication()).user.access_token.toString()
RetrofitClient.instance.fetchUser(token)
.enqueue(object : Callback<My_account_base_response> {
override fun onFailure(call: Call<My_account_base_response>, t: Throwable) {
Log.d("res", "" + t)
_accountResponseData.value = null
}
override fun onResponse(
call: Call<My_account_base_response>,
response: Response<My_account_base_response>
) {
var res = response
if (res.body()?.status == 200) {
_accountResponseData.value = response.body()
} else {
try {
val jObjError =
JSONObject(response.errorBody()!!.string())
Toast.makeText(
getApplication(),
jObjError.getString("user_msg"),
Toast.LENGTH_LONG
).show()
} catch (e: Exception) {
Log.e("errorrr", e.message)
}
}
}
})
}
}
Don't make initial API call along with LiveData creation, it's okay to do in most of cases but if you're updating LiveData on response of that call then it's good to make it separately like during init block.
It's good practice not to allow Ui (Activity/Fragments) to modify LiveDatas of ViewModel directly. So, that's good sign you're following such pattern by having private MutableLiveData exposed as public LiveData, but do it correctly as suggested.
Side note: Your view model doesn't need to be LifecycleObserver. LifecycleObserver is used for some custom class/component which needs to be managed by their self by silently observing/depending on activity lifecycle independently. That's not the use case of ViewModel.
The only thing that I found why your code wasn't working correctly is because you were creating & observing ViewModel & LiveData over & over again as new objects from onResume method where you called hello() method.
Let me know if something don't make sense or missing.

Android Paging Library Doesn't Scroll Up Correctly

I'm using the JetPack paging library with a network call (no database).
I am able to scroll down smoothly and load new pages of data, BUT, when scrolling up it stutters and quickly jumps to the top of the list. I am unable to scroll up smoothly.
Here is a video showing the problem: https://imgur.com/a/bRoelyF
What I've Tried:
Enabling retrofit caching
Using a LinearLayoutManager instead of GridLayoutManager
Following old and newer tutorials with versions 1.0.1 and 2.1.2 of the library
Here is my code:
MovieDataSource.kt:
private val movieDbApi: TheMovieDbApi
) : PageKeyedDataSource<Int, Movie>() {
override fun loadBefore(params: LoadParams<Int>, callback: LoadCallback<Int, Movie>) {}
override fun loadInitial(params: LoadInitialParams<Int>, callback: LoadInitialCallback<Int, Movie>) {
movieDbApi.getTopRatedMovies(BuildConfig.MOVIE_DATA_BASE_API, FIRST_PAGE).subscribe(
{
it?.let { callback.onResult(it.results, null, FIRST_PAGE + 1) }
}, {}
)
}
override fun loadAfter(params: LoadParams<Int>, callback: LoadCallback<Int, Movie>) {
movieDbApi.getTopRatedMovies(BuildConfig.MOVIE_DATA_BASE_API, params.key).subscribe(
{
val key = params.key + 1
it?.let {callback.onResult(it.results, key)
}
},{}
)
}
MovieDataSourceFactory.kt:
class MovieDataSourceFactory(private val movieDbApi: TheMovieDbApi) :
DataSource.Factory<Int, Movie>() {
// Is this where the MovieDataSource callBacks are sent?
val movieLiveDataSource = MutableLiveData<MovieDataSource>()
override fun create(): DataSource<Int, Movie> {
val movieDataSource = MovieDataSource(movieDbApi)
movieLiveDataSource.postValue(movieDataSource)
return movieDataSource
}
}
HomeViewModel.kt:
class HomeViewModel #Inject constructor(
theMovieDbApi: TheMovieDbApi
) : DisposingViewModel() {
var moviePagedList: LiveData<PagedList<Movie>>
private var liveDataSource: LiveData<MovieDataSource>
init {
val movieDataSourceFactory = MovieDataSourceFactory(theMovieDbApi)
liveDataSource = movieDataSourceFactory.movieLiveDataSource
val config = PagedList.Config.Builder()
.setEnablePlaceholders(true)
.setPageSize(MovieDataSource.PAGE_SIZE)
.build()
moviePagedList = LivePagedListBuilder(movieDataSourceFactory, config)
.build()
}
}
HomeViewModel.kt:
class HomeActivity : AppCompatActivity() {
#Inject
internal lateinit var viewModelFactory: ViewModelFactory<HomeViewModel>
private lateinit var viewModel: HomeViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_home)
AndroidInjection.inject(this)
val adapter = HomeAdapter()
movie_recycler_view.setHasFixedSize(false)
movie_recycler_view.layoutManager = LinearLayoutManager(this)
val viewModel = ViewModelProvider(this, viewModelFactory).get(HomeViewModel::class.java)
viewModel.moviePagedList.observe(this, Observer {
adapter.submitList(it)
})
movie_recycler_view.adapter = adapter
}
}
HomeAdapter.kt:
class HomeAdapter : PagedListAdapter<Movie, HomeAdapter.MovieViewHolder>(USER_COMPARATOR) {
override fun getItemCount(): Int {
return super.getItemCount()
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MovieViewHolder {
val view = LayoutInflater.from(parent.context)
.inflate(R.layout.item_movie, parent, false)
return MovieViewHolder(view)
}
override fun onBindViewHolder(holder: MovieViewHolder, position: Int) {
val movie = getItem(position)
movie?.let { holder.bind(it) }
}
class MovieViewHolder(view: View) : RecyclerView.ViewHolder(view) {
fun bind(movie: Movie) {
Picasso.get().load(BASE_IMAGE_URL + movie.poster_path).into(itemView.movie_image)
}
}
companion object {
private val USER_COMPARATOR = object : DiffUtil.ItemCallback<Movie>() {
override fun areItemsTheSame(oldItem: Movie, newItem: Movie): Boolean =
oldItem.id == newItem.id
override fun areContentsTheSame(oldItem: Movie, newItem: Movie): Boolean =
oldItem == newItem
}
}
}
If anyone has a solution or spots a problem I'd love to hear it!

I solved the problem.
It's because I didn't add a placeholder image to Picasso in the adapter.
Before:
Picasso.get()
.load(BASE_IMAGE_URL + movie.poster_path)
.into(itemView.movie_image)
After:
Picasso.get()
.load(BASE_IMAGE_URL + movie.poster_path)
.placeholder(R.drawable.placeholder)
.into(itemView.movie_image)
Now it loads well.
Another consideration is the size of the image, it takes a while to load a larger image especially if you are loading many of them within an infinite scroll.

How to observe LiveData<PagedList> with android paging in kotlin

I can't observe the LiveData<PagedList> change in activity, but the UI is updated(the list has grown in activty).
I can only observe it once when the livedata is initialized.
when the paging library call loadAfter method, the ui is updated, but didn't call pageList.observe{}
Firstly, I put the process of data request into the Kotlin Coroutines, I can't observe the data change, then I used asynchronous requests instead.It still didn't work.
Here is my code:
PlayActivity main code
private val commentAdapter =
object : BasePagedAdapter(diffCallback, this) {
// just bind recycleview item and corresponding view model. etc.
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = DataBindingUtil.setContentView(this, R.layout.activity_play)
binding.vm = vm
binding.lifecycleOwner = this
val workId = intent.getLongExtra(WORK_ID, 0)
vm.listComment(workId)
play_rv_comment.adapter = commentAdapter
/* herer is the problem*/
vm.commentList.observe(this, Observer {
/*only log once when called loadInitial*/
LogUtils.e("observe", it)
commentAdapter.submitList(it)
})
PlayViewModel
class PlayViewModel : BaseViewModel() {
var workId: Long = 0
// the data which I want to observe
lateinit var commentList: LiveData<PagedList<WorkComment>>
private val commentPageSize = 15
fun listComment(workId: Long) {
// init by DataSource.Factory in android paging library
commentList = BaseDataSourceFactory(workId).toLiveData(commentPageSize)
}
DataSource.Factory in Android paging
class BaseDataSourceFactory(
val workId: Long
) :
DataSource.Factory<Long, WorkComment>() {
override fun create(): DataSource<Long, WorkComment> {
return object : PageKeyedDataSource<Long, WorkComment>() {
override fun loadInitial(
params: LoadInitialParams<Long>,
callback: LoadInitialCallback<Long, WorkComment>
) {
try {
val res = RetrofitUtil.getInstanceWithJwt().create(WorkCommentApi::class.java)
.listComment(
workId, 1, params.requestedLoadSize
)
res.enqueue(object : retrofit2.Callback<TResult> {
override fun onFailure(call: Call<TResult>, t: Throwable) {
}
override fun onResponse(call: Call<TResult>, response: Response<TResult>) {
callback.onResult(
response.body()!!.toList(WorkComment::class.java),
null, 2)
}
})
} catch (e: SocketTimeoutException) {
ToastUtils.showShort("请稍候重试")
} catch (e: Exception) {
LogUtils.e(e.localizedMessage)
}
}
// called many times, but I can't observe the PagedList change
override fun loadAfter(
params: LoadParams<Long>,
callback: LoadCallback<Long, WorkComment>
) {
val res = RetrofitUtil.getInstanceWithJwt().create(WorkCommentApi::class.java)
.listComment(
workId, 1, params.requestedLoadSize
)
res.enqueue(object : retrofit2.Callback<TResult> {
override fun onFailure(call: Call<TResult>, t: Throwable) {
}
override fun onResponse(call: Call<TResult>, response: Response<TResult>) {
callback.onResult(
response.body()!!.toList(WorkComment::class.java),
params.key + 1
)
}
})
}
override fun loadBefore(
params: LoadParams<Long>,
callback: LoadCallback<Long, WorkComment>
) {
}
}
}
}
Retrofit Api
interface WorkCommentApi {
/**
* list comment
*/
#GET("public/work/comment")
fun listComment(#Query("workId") workId: Long, #Query("current") current: Long, #Query("size") size: Int): Call<TResult>
}
I want to know what should I do to observe the LiveData<PagedList> change

This is happening because each time you call vm.listComment(workId), the object you first bound in activity is killed and new object is created.
You can use Transformations with MediatorLiveData.
Activity:
viewModel.logout().observe(this, Observer {
// do here
})
ViewModel:
class RepackViewModel(app: Application) : BaseViewModel(app) {
// IMPORTANT - Mediator
val logout = MediatorLiveData<PagedList<WorkComment>>()
fun logout() : LiveData<PagedList<WorkComment>> = logout
init {
// IMPORTANT - passes repo update to activity
logout.addSource(repo.getLogoutResponse()) { logout.postValue(it) }
}
}
Repository:
class BaseRepository(val app: Application) {
private val logout = MutableLiveData<PagedList<WorkComment>>()
fun getLogoutResponse(): LiveData<PagedList<WorkComment>> = logout
override fun create(): DataSource<Long, WorkComment> {
//when you get your data
logout.value = // your value
}

You need to have your work id be mutable data to be observed by the transformation. so whenever you update your work, id, it will fetch comments. Like Thus...
ViewModel:
val workIdMutableLiveData: MutableLiveData<Int> = MutableLiveData(workId)
//This performs the meat of the work to display the items in the recyclerview
var commentsList = Transformations.switchMap(workIdMutableLiveData) { workId ->
val config = PagedList.Config.Builder()
.setEnablePlaceholders(false)
.setPageSize(pagingLimit)
.build()
val pagedListBuilder = LivePagedListBuilder<Long, WorkComment>(BaseDataSourceFactory(workId), config)
pagedListBuilder.build()
}
Then in your activity, observe
yourViewModel.commentsList.observe(this, Observer { list ->
list ?: return#Observer
adapter.submitList(list)
yourRecyclerView.adapter = adapter
})
Whenever you update the workIdMutableLiveData by doing a
workIdMutableLiveData.postValue(workId)
...The recyclerview will update. Your recyclerview must inherit from PagedListAdapter.

After testing, I knew list couldn't be observed when it has inner data change, like add(), remove(). etc.
It only be observed when its reference has been changed, like create or assignment operation:
list.value = null
So I couldn't observe the data change of LiveData<List>

Paging Library doesn't trigger observe when load initial data

I'm setting up paged list of items that i fetch in datasource with coroutines, also i'm observing this list to submit it in adapter, but when it initially loads some data, it does not trigger observe callback. What can i do to handle this ?
I tried to debug this thing, and i found that ArrayList> mCallbacks list in PagedList, does not contain any callbacks when it tried to notify data changes, but i don't know what to do with this.
Data source from data will be fetched and paged.
class PagedDataSource(private val account: Account, private val getItems: GetItems): PageKeyedDataSource<Int, Item>() {
override fun loadInitial(
params: LoadInitialParams<Int>,
callback: LoadInitialCallback<Int, Transaction>
) {
GlobalScope.launch {
val startPage = 0
account.id?.let {
val items = getItems(it, startPage).body.toMutableList()
callback.onResult(items, null, 1)
}
}
}
override fun loadAfter(params: LoadParams<Int>, callback: LoadCallback<Int, Item>) {
GlobalScope.launch {
account.id?.let {
val list = getItems(it, params.key)
val items = list.body.toMutableList()
callback.onResult(items, if (params.key >= list.totalPages) null else params.key + 1)
}
}
}
override fun loadBefore(params: LoadParams<Int>, callback: LoadCallback<Int, Item>) {
//NO NEED
}
}
code in fragment:
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
pagedAdapter = PagedAdapter()
vItems.layoutManager = LinearLayoutManager(context)
vItems.isNestedScrollingEnabled = false
vItems.adapter = pagedAdapter
items.observe(viewLifecycleOwner, Observer { items ->
if (items != null && items.isNotEmpty()) {
pagedAdapter.submitList(items)
} else {
vItemsTitle.visibility = View.VISIBLE
}
})
}
And finally code in my viewmodel
init {
items = initializedPagedList()
}
private fun initializedPagedList() : LiveData<PagedList<Item>> {
val factory = object: DataSource.Factory<Int, Item>() {
override fun create(): DataSource<Int, Item> {
return PagedDataSource(account, getItems)
}
}
val config = PagedList.Config.Builder()
.setPageSize(20)
.setEnablePlaceholders(false)
.build()
return LivePagedListBuilder(factory, config).build()
}
I expect that data will be fetched after success api calls in loadInitial method and trigger observe callback.

Finally after researching, i found answer for my question.
Problem was in this code
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
pagedAdapter = PagedAdapter()
vItems.layoutManager = LinearLayoutManager(context)
vItems.isNestedScrollingEnabled = false
vItems.adapter = pagedAdapter
items.observe(viewLifecycleOwner, Observer { items ->
if (items != null && items.isNotEmpty()) {
pagedAdapter.submitList(items)
} else {
vItemsTitle.visibility = View.VISIBLE
}
})
}
I needed to change this to
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
pagedAdapter = PagedAdapter()
vItems.layoutManager = LinearLayoutManager(context)
vItems.isNestedScrollingEnabled = false
vItems.adapter = pagedAdapter
items.observe(viewLifecycleOwner, Observer { items ->
pagedAdapter.submitList(items)
})
}
I think that's happening because in foreground PagedList works asynchronously/ and you need to submit this list once and after that datasource will send updates directly to the adapter, avoiding observing. In my case i'm submiting if list is not empty, but it will always empty when you're creating PagedList at the start.
Good luck everyone !

BoundaryCallback in PageList never gets called

I'm using Paging Library with PagedListAdapter, I'm using BoundaryCallback in PagedList to know when the user reaches the end of the list. The problem is that the method in my callback never gets called.
This is my data source code:
class PropertyDataSource : ItemKeyedDataSource<Int, Property>() {
override fun loadInitial(params: LoadInitialParams<Int>, callback: LoadInitialCallback<Property>) {
callback.onResult(getProperties(1, params.requestedLoadSize))
}
override fun loadAfter(params: LoadParams<Int>, callback: LoadCallback<Property>) {
Thread.sleep(1000)
callback.onResult(getProperties(params.key + 1, params.requestedLoadSize + params.key))
}
override fun loadBefore(params: LoadParams<Int>, callback: LoadCallback<Property>) {
}
override fun getKey(item: Property): Int {
return item.id
}
}
my code for boundary callback is
class MyBoundryCallBack: PagedList.BoundaryCallback<Property>() {
override fun onItemAtEndLoaded(itemAtEnd: Property) {
Log.e("alz", "at end $itemAtEnd")
}
override fun onItemAtFrontLoaded(itemAtFront: Property) {
Log.e("alz", "at front $itemAtFront")
}
override fun onZeroItemsLoaded() {
Log.e("alz", "zero item loaded")
}
}
here is my activity code
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val adapter = MyListAdapter(PropertyDiffCallback())
mainRecyclerView.adapter = adapter
mainRecyclerView.layoutManager = LinearLayoutManager(this)
val propertyDataSourceFactory = PropertyDataSourceFactory()
val config = PagedList.Config.Builder()
.setPageSize(2)
.setInitialLoadSizeHint(3)
.setEnablePlaceholders(false)
.build()
val pagedList = LivePagedListBuilder(propertyDataSourceFactory, config)
.setBoundaryCallback(MyBoundryCallBack())
.build()
pagedList.observe(this, Observer {
adapter.submitList(it)
}
}
And my code for Adapter is look like this
class MyListAdapter(diffCallback: DiffUtil.ItemCallback<Property>) :
PagedListAdapter<Property, RecyclerView.ViewHolder>(diffCallback) {
class ItemHolder(itemView: View) : RecyclerView.ViewHolder(itemView){
val titleTV: TextView = itemView.findViewById(R.id.title)
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
return ItemHolder(LayoutInflater.from(parent.context).inflate(R.layout.item_property, parent, false))
}
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
if(getItem(position) == null) return
val itemHolder = holder as ItemHolder
itemHolder.titleTV.text = getItem(position)!!.title
}
}
And here is my implementation of getProperties() that will return some mock data. Later on, I'm going to change it to load data from the server.
fun getProperties(from: Int, to: Int): List<Property> {
val list = ArrayList<Property>()
for (i in from..to){
list.add(Property(i, "item $i"))
}
return list
}
Note that, my code works fine and my adapter requesting more data as it goes to the end, I just don't get the callback when PagedList gets to the end.