I'm trying to integrate a VerticalGridSupportFragment() inside a BrowseSupportFragment() based on some of the Leanback examples.
On running the code below (partial snippet provided below) I get the exception java.lang.IllegalArgumentException: Fragment must implement MainFragmentAdapterProvider
I'm struggling to understand how to implement the interface methods defined by MainFragmentAdapterProvider [i.e getMainFragmentAdapter()]. Could anyone provide insight surrounding this issue, or could you provide an example? I've tried to return the mRowsAdapter, however it was not of the correct type.
Any help would really be appreciated, thanks!
class MainFragmentByGroupFragment : BrowseSupportFragment() {
override fun onActivityCreated(savedInstanceState: Bundle?) {
Log.i(TAG, "onCreate")
super.onActivityCreated(savedInstanceState)
prepareBackgroundManager()
mainFragmentRegistry.registerFragment(
PageRow::class.java,
PageRowFragmentFactory(mBackgroundManager)
)
setupUIElements()
createRows()
setupEventListeners()
}
private class PageRowFragmentFactory(backgroundManager: BackgroundManager) : BrowseSupportFragment.FragmentFactory<androidx.fragment.app.Fragment>() {
override fun createFragment(rowObj: Any?): androidx.fragment.app.Fragment {
val row = rowObj as Row
return ChannelFragment()
}
}
}
class ChannelFragment : VerticalGridSupportFragment(), OnItemViewClickedListener, BrowseSupportFragment.MainFragmentAdapterProvider {
private var mRowsAdapter: ArrayObjectAdapter? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
mRowsAdapter = ArrayObjectAdapter(CardPresenter())
setAdapter(mRowsAdapter)
setOnItemViewClickedListener(this)
createRows()
}
private fun createRows() {
val gridPresenter = VerticalGridPresenter()
gridPresenter.numberOfColumns = NUM_COLUMNS
setGridPresenter(gridPresenter)
setOnItemViewClickedListener(this)
val list = MovieList.list
for (i in 0 until 100) {
mRowsAdapter!!.add(list[i % 5])
}
}
override fun onItemClicked(
itemViewHolder: Presenter.ViewHolder?, item: Any,
rowViewHolder: RowPresenter.ViewHolder?, row: Row?
) {
}
override fun getMainFragmentAdapter(): BrowseSupportFragment.MainFragmentAdapter<*> {
TODO("Not yet implemented")
}
companion object {
private const val NUM_COLUMNS = 5
}
}
I think you should implement getMainFragmentAdapter.
Add the following to ChannelFragment:
private val mMainFragmentAdapter: BrowseSupportFragment.MainFragmentAdapter<*> =
object : BrowseSupportFragment.MainFragmentAdapter<Fragment?>(this) {
override fun setEntranceTransitionState(state: Boolean) {
}
}
And return mMainFragmentAdapter in getMainFragmentAdapter:
override fun getMainFragmentAdapter(): BrowseSupportFragment.MainFragmentAdapter<*> {
return mMainFragmentAdapter
}
I m getting data from two End points using flows and assigning those two list to temporary list in ViewModel. For this purpose, I'm using combine function and returning result as stateFlows with stateIn operator but that's not working. Can anyone point me out where I go wrong please.
ViewModel.kt
private val _movieItem: MutableStateFlow<State<List<HomeRecyclerViewItems>>> =
MutableStateFlow(State.Loading())
val movieItems: StateFlow<State<List<HomeRecyclerViewItems>>> = _movieItem
fun getHomeItemList() {
viewModelScope.launch {
val testList: Flow<State<List<HomeRecyclerViewItems.Movie>>> =
settingsRepo.getMovieList().map {
State.fromResource(it)
}
val directorList: Flow<State<List<HomeRecyclerViewItems.Directors>>> =
settingsRepo.getDirectorList().map {
State.fromResource(it)
}
_movieItem.value = combine(testList, directorList) { testList, directorList ->
testList + directorList // This is not working as "+" Unresolve Error
}.stateIn(
viewModelScope,
SharingStarted.WhileSubscribed(5000),
State.loading<Nothing>()
) as State<List<HomeRecyclerViewItems>> // Unchecked cast: StateFlow<Any> to State<List<HomeRecyclerViewItems>>
}
Repository.kt
fun getMovieList(): Flow<ResponseAPI<List<HomeRecyclerViewItems.Movie>>> {
return object :
NetworkBoundRepository<List<HomeRecyclerViewItems.Movie>, List<HomeRecyclerViewItems.Movie>>() {
override suspend fun saveRemoteData(response: List<HomeRecyclerViewItems.Movie>) {
}
override fun fetchFromLocal() {
}
override suspend fun fetchFromRemote(): Response<List<HomeRecyclerViewItems.Movie>> =
apiInterface.getMoviesList()
}.asFlow()
}
fun getDirectorList(): Flow<ResponseAPI<List<HomeRecyclerViewItems.Directors>>> {
return object :
NetworkBoundRepository<List<HomeRecyclerViewItems.Directors>, List<HomeRecyclerViewItems.Directors>>() {
override suspend fun saveRemoteData(response: List<HomeRecyclerViewItems.Directors>) {
}
override fun fetchFromLocal() {
}
override suspend fun fetchFromRemote(): Response<List<HomeRecyclerViewItems.Directors>> =
apiInterface.getDirectorsList()
}.asFlow()
}
Network BoundRepository.kt
#ExperimentalCoroutinesApi
abstract class NetworkBoundRepository<RESULT, REQUEST> {
fun asFlow() = flow<ResponseAPI<REQUEST>> {
val apiResponse = fetchFromRemote()
val remotePosts = apiResponse.body()
if (apiResponse.isSuccessful && remotePosts != null) {
emit(ResponseAPI.Success(remotePosts))
} else {
emit(ResponseAPI.Failed(apiResponse.errorBody()!!.string()))
}
}.catch { e ->
e.printStackTrace()
emit(ResponseAPI.Failed("Server Problem! Please try again Later. "))
}
#WorkerThread
protected abstract suspend fun saveRemoteData(response: REQUEST)
#MainThread
protected abstract fun fetchFromLocal()
#MainThread
protected abstract suspend fun fetchFromRemote(): Response<REQUEST>
}
Endpoints with Sealed Class
#GET("directors")
fun getDirectorsList(): Response<List<HomeRecyclerViewItems.Directors>>
#GET("movies")
fun getMoviesList(): Response<List<HomeRecyclerViewItems.Movie>>
sealed class HomeRecyclerViewItems {
class Title(
val id: Int,
val title: String
) : HomeRecyclerViewItems()
class Movie(
val id: Int,
val title: String,
val thumbnail: String,
val releaseDate: String
) : HomeRecyclerViewItems()
class Directors(
val id: Int,
val name: String,
val avator: String,
val movie_count: Int
) : HomeRecyclerViewItems()
}
Fragment.kt
#AndroidEntryPoint
#ExperimentalCoroutinesApi
class SettingsFragment : BaseBottomTabFragment() {
private var _binding: FragmentSettingsBinding? = null
private val binding get() = _binding!!
private val viewModel by viewModels<SettingViewModel>()
#Inject
lateinit var recyclerViewAdapter: RecyclerViewAdapter
#Inject
lateinit var bundle: Bundle
var finalList = mutableListOf<HomeRecyclerViewItems>()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View {
// Inflate the layout for this fragment
_binding = FragmentSettingsBinding.inflate(layoutInflater,container,false)
val view = binding.root
binding.rvMovie.apply {
setHasFixedSize(true)
layoutManager = LinearLayoutManager(activity)
}
bundle.putString("Hello","hihg")
Toast.makeText(activity, "${bundle.getString("Hello")}", Toast.LENGTH_SHORT).show()
finalList.add(HomeRecyclerViewItems.Title(1,"hello"))
return view
}
private fun observeList() {
viewLifecycleOwner.lifecycleScope.launch {
viewLifecycleOwner.lifecycle.repeatOnLifecycle(Lifecycle.State.STARTED){
launch {
viewModel.movieItems.collect { state ->
when(state){
is State.Loading ->{
}
is State.Success->{
if (state.data.isNotEmpty()){
recyclerViewAdapter = RecyclerViewAdapter()
binding.rvMovie.adapter = recyclerViewAdapter
recyclerViewAdapter.submitList(finalList)
}
}
is State.Error -> {
Toast.makeText(activity, "Error", Toast.LENGTH_SHORT).show()
}
else -> Unit
}
}
}
}
}
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
(activity as MainActivity).binding.ivSearch.isGone = true
viewModel.getHomeItemList()
observeList()
}
override fun onDestroyView() {
super.onDestroyView()
_binding = null
}
}
Note: I m following this tutorial simpliedCoding for api data for multirecyclerview but want to implement it with Kotlin State Flow. Any help in this regard is highly appreciated. Thanks.
Your problem is in here
val testList: Flow<State<List<HomeRecyclerViewItems.Movie>>> =
settingsRepo.getMovieList().map {
State.fromResource(it)
}
val directorList: Flow<State<List<HomeRecyclerViewItems.Directors>>> =
settingsRepo.getDirectorList().map {
State.fromResource(it)
}
_movieItem.value = combine(testList, directorList) { testList, directorList ->
testList + directorList
}
They are not returning a List<HomeRecyclerViewItems>, but a State<List<HomeRecyclerViewItems>. Maybe a better name for the variables are testsState and directorsState. After that it will be more clear why you need to unpack the values before combining the lists
_movieItem.value = combine(testsState, directorsState) { testsState, directorsState ->
val homeRecyclerViewItems = mutableListOf<HomeRecyclerViewItems>()
if (testsState is Success) homeRecyclerViewItems.add(testsState.data)
if (directorsState is Success) homeRecyclerViewItems.add(directorsState.data)
homeRecyclerViewItems
}
I have the following ViewModel class -
class VerifyOtpViewModel : ViewModel() {
private var existingUserProfileData: MutableLiveData<TwoVerteUsers.TwoVerteUser>? = null
fun checkInfoForAuthenticatedUser(authorization: String, user: String) {
ProfileNetworking.getUsersProfiles(authorization, GetUserProfilesBodyModel(listOf(user)), object : ProfileNetworking.OnGetUserProfilesListener {
override fun onSuccess(model: TwoVerteUsers) {
existingUserProfileData?.value = model[0]
}
override fun onError(reason: String) {
Log.d("existingProfile", reason)
}
})
}
fun getExistingUserProfileData(): LiveData<TwoVerteUsers.TwoVerteUser>? {
if (existingUserProfileData == null) return null
return existingUserProfileData as LiveData<TwoVerteUsers.TwoVerteUser>
}
}
and the following observer -
private fun initViewModel() {
verifyOtpViewModel = ViewModelProvider(this).get(VerifyOtpViewModel::class.java)
verifyOtpViewModel.getExistingUserProfileData()?.observe(this, Observer {
if (it != null)
Log.d("existingProfile", it.username)
})
}
For some reason the observe is never triggered even after the MutableLiveData object is being given a value
Tried to search for a solution here at stackoverflow but nothing helped
what am I missing?
refactor your code to this, and you should be good to go:
class VerifyOtpViewModel : ViewModel() {
private val _existingUserProfileData = MutableLiveData<TwoVerteUsers.TwoVerteUser>()
val existingUserProfileData: LiveData<TwoVerteUsers.TwoVerteUser>
get() = _existingUserProfileData
fun checkInfoForAuthenticatedUser(authorization: String, user: String) {
ProfileNetworking.getUsersProfiles(
authorization,
GetUserProfilesBodyModel(listOf(user)),
object : ProfileNetworking.OnGetUserProfilesListener {
override fun onSuccess(model: TwoVerteUsers) {
existingUserProfileData.value = model[0]
}
override fun onError(reason: String) {
Log.d("existingProfile", reason)
}
})
}
}
And observing:
verifyOtpViewModel.existingUserProfileData.observe(this, Observer {
.....
})
I am trying to remove/clear the cache mechanism from AWSAppSyncClient.
Now the problem is i am getting the value which is store or request early (it is cacheing the value and returning that value)
what i want is, it should return the value from the api.(should not cache the value).
i have tried this :
AWSAppSyncClient.builder()
.context(syncPort.androidContext())
.awsConfiguration(AWSConfiguration(syncPort.androidContext()))
.build()
.clearCaches(ClearCacheOptions.builder().clearSubscriptions().build())
Query code :
override fun getMedication(date: String): Single<SampleAdministration> {
return Single.create<SampleAdministration> { emitter ->
client.query(
GetSampleQuery.builder().date(date).build()
).enqueue(object : GraphQLCall.Callback<GetSampleQuery.Data>() {
override fun onFailure(e: ApolloException) {
emitter.onError(e)
}
override fun onResponse(response: Response<GetSampleQuery.Data>) {
val data = response.data()?.sample
val sampleAdministration = object : SampleAdministration {
override var date: String? =
data?.date()
}
emitter.onSuccess(sampleAdministration)
}
})
}
}
i have remove clearCaches from AWSAppSyncClient.builder()
and added responseFetcher in query
override fun getMedication(date: String): Single<SampleAdministration> {
return Single.create<SampleAdministration> { emitter ->
client.query(
GetSampleQuery.builder().date(date).build()
).responseFetcher(AppSyncResponseFetchers.NETWORK_ONLY).enqueue(object : GraphQLCall.Callback<GetSampleQuery.Data>() {
override fun onFailure(e: ApolloException) {
emitter.onError(e)
}override fun onResponse(response: Response<GetSampleQuery.Data>) {
val data = response.data()?.sample
val sampleAdministration = object : SampleAdministration {
override var date: String? =
data?.date()
}
emitter.onSuccess(sampleAdministration)
}
})
}
So I use kotlin for android, and when inflating views, I tend to do the following:
private val recyclerView by lazy { find<RecyclerView>(R.id.recyclerView) }
This method will work. However, there is a case in which it will bug the app. If this is a fragment, and the fragment goes to the backstack, onCreateView will be called again, and the view hierarchy of the fragment will recreated. Which means, the lazy initiated recyclerView will point out to an old view no longer existent.
A solution is like this:
private lateinit var recyclerView: RecyclerView
And initialise all the properties inside onCreateView.
My question is, is there any way to reset lazy properties so they can be initialised again? I like the fact initialisations are all done at the top of a class, helps to keep the code organised. The specific problem is found in this question: kotlin android fragment empty recycler view after back
Here is a quick version of a resettable lazy, it could be more elegant and needs double checked for thread safety, but this is basically the idea. You need something to manage (keep track) of the lazy delegates so you can call for reset, and then things that can be managed and reset. This wraps lazy() in these management classes.
Here is what your final class will look like, as an example:
class Something {
val lazyMgr = resettableManager()
val prop1: String by resettableLazy(lazyMgr) { ... }
val prop2: String by resettableLazy(lazyMgr) { ... }
val prop3: String by resettableLazy(lazyMgr) { ... }
}
Then to make the lazy's all go back to new values on next time they are accessed:
lazyMgr.reset() // prop1, prop2, and prop3 all will do new lazy values on next access
The implementation of the resettable lazy:
class ResettableLazyManager {
// we synchronize to make sure the timing of a reset() call and new inits do not collide
val managedDelegates = LinkedList<Resettable>()
fun register(managed: Resettable) {
synchronized (managedDelegates) {
managedDelegates.add(managed)
}
}
fun reset() {
synchronized (managedDelegates) {
managedDelegates.forEach { it.reset() }
managedDelegates.clear()
}
}
}
interface Resettable {
fun reset()
}
class ResettableLazy<PROPTYPE>(val manager: ResettableLazyManager, val init: ()->PROPTYPE): Resettable {
#Volatile var lazyHolder = makeInitBlock()
operator fun getValue(thisRef: Any?, property: KProperty<*>): PROPTYPE {
return lazyHolder.value
}
override fun reset() {
lazyHolder = makeInitBlock()
}
fun makeInitBlock(): Lazy<PROPTYPE> {
return lazy {
manager.register(this)
init()
}
}
}
fun <PROPTYPE> resettableLazy(manager: ResettableLazyManager, init: ()->PROPTYPE): ResettableLazy<PROPTYPE> {
return ResettableLazy(manager, init)
}
fun resettableManager(): ResettableLazyManager = ResettableLazyManager()
And some unit tests to be sure:
class Tester {
#Test fun testResetableLazy() {
class Something {
var seed = 1
val lazyMgr = resettableManager()
val x: String by resettableLazy(lazyMgr) { "x ${seed}" }
val y: String by resettableLazy(lazyMgr) { "y ${seed}" }
val z: String by resettableLazy(lazyMgr) { "z $x $y"}
}
val s = Something()
val x1 = s.x
val y1 = s.y
val z1 = s.z
assertEquals(x1, s.x)
assertEquals(y1, s.y)
assertEquals(z1, s.z)
s.seed++ // without reset nothing should change
assertTrue(x1 === s.x)
assertTrue(y1 === s.y)
assertTrue(z1 === s.z)
s.lazyMgr.reset()
s.seed++ // because of reset the values should change
val x2 = s.x
val y2 = s.y
val z2 = s.z
assertEquals(x2, s.x)
assertEquals(y2, s.y)
assertEquals(z2, s.z)
assertNotEquals(x1, x2)
assertNotEquals(y1, y2)
assertNotEquals(z1, z2)
s.seed++ // but without reset, nothing should change
assertTrue(x2 === s.x)
assertTrue(y2 === s.y)
assertTrue(z2 === s.z)
}
}
I find a convenient method:
import java.util.concurrent.atomic.AtomicReference
import kotlin.reflect.KProperty
fun <T> resetableLazy(initializer: () -> T) = ResetableDelegate(initializer)
class ResetableDelegate<T>(private val initializer: () -> T) {
private val lazyRef: AtomicReference<Lazy<T>> = AtomicReference(
lazy(
initializer
)
)
operator fun getValue(thisRef: Any?, property: KProperty<*>): T {
return lazyRef.get().getValue(thisRef, property)
}
fun reset() {
lazyRef.set(lazy(initializer))
}
}
test:
import org.junit.Assert
import org.junit.Test
class ResetableLazyData {
var changedData = 0
val delegate = resetableLazy { changedData }
val readOnlyData by delegate
}
class ResetableLazyTest {
#Test
fun testResetableLazy() {
val data = ResetableLazyData()
data.changedData = 1
Assert.assertEquals(data.changedData, data.readOnlyData)
data.changedData = 2
Assert.assertNotEquals(data.changedData, data.readOnlyData)
data.delegate.reset()
Assert.assertEquals(data.changedData, data.readOnlyData)
data.changedData = 3
Assert.assertNotEquals(data.changedData, data.readOnlyData)
}
}
I had the same task, and this is what I used:
import kotlin.properties.ReadOnlyProperty
import kotlin.reflect.KProperty
class SingletonLazy<T : Any>(val initBlock: () -> T, val clazz: Class<T>) {
operator fun <R> provideDelegate(ref: R, prop: KProperty<*>): ReadOnlyProperty<R, T> = delegate()
#Suppress("UNCHECKED_CAST")
private fun <R> delegate(): ReadOnlyProperty<R, T> = object : ReadOnlyProperty<R, T> {
override fun getValue(thisRef: R, property: KProperty<*>): T {
val hash = clazz.hashCode()
val cached = singletonsCache[hash]
if (cached != null && cached.javaClass == clazz) return cached as T
return initBlock().apply { singletonsCache[hash] = this }
}
}
}
private val singletonsCache = HashMap<Int, Any>()
fun <T> clearSingleton(clazz: Class<T>) : Boolean {
val hash = clazz.hashCode()
val result = singletonsCache[hash]
if (result?.javaClass != clazz) return false
singletonsCache.remove(hash)
return true
}
inline fun <reified T : Any> singletonLazy(noinline block: () -> T): SingletonLazy<T>
= SingletonLazy(block, T::class.java)
usage:
val cat: Cat by singletonLazy { Cat() }
fun main(args: Array<String>) {
cat
println(clearSingleton(Cat::class.java))
cat // cat will be created one more time
println(singletonsCache.size)
}
class Cat {
init { println("creating cat") }
}
Of course, you may have you own caching strategies.
If you want something very simple, extends Lazy<T> and yet efficient in few lines of code, you could use this
class MutableLazy<T>(private val initializer: () -> T) : Lazy<T> {
private var cached: T? = null
override val value: T
get() {
if (cached.isNull()) {
cached = initializer()
}
#Suppress("UNCHECKED_CAST")
return cached as T
}
fun reset() {
cached = null
}
override fun isInitialized(): Boolean = cached != null
companion object {
fun <T> resettableLazy(value: () -> T) = MutableLazy(value)
}
}
Use it like this:
class MainActivity() {
val recyclerViewLazy = MutableLazy.resettable {
findViewById<RecyclerView>(R.id.recyclerView)
}
val recyclerView by recyclerViewLazy
// And later on
override onCreate(savedInstanceState: Bundle?) {
recyclerViewLazy.reset() /** On next get of the recyclerView, it would be updated*/
}
}
Borrowed partly from
lazy(LazyThreadSafetyMode.NONE) { }
provided in the stlib
you can try this
fun <P, T> renewableLazy(initializer: (P) -> T): ReadWriteProperty<P, T> =
RenewableSynchronizedLazyWithThisImpl({ t, _ ->
initializer.invoke(t)
})
fun <P, T> renewableLazy(initializer: (P, KProperty<*>) -> T): ReadWriteProperty<P, T> =
RenewableSynchronizedLazyWithThisImpl(initializer)
class RenewableSynchronizedLazyWithThisImpl<in T, V>(
val initializer: (T, KProperty<*>) -> V,
private val lock: Any = {}
) : ReadWriteProperty<T, V> {
#Volatile
private var _value: Any? = null
override fun getValue(thisRef: T, property: KProperty<*>): V {
val _v1 = _value
if (_v1 !== null) {
#Suppress("UNCHECKED_CAST")
return _v1 as V
}
return synchronized(lock) {
val _v2 = _value
if (_v2 !== null) {
#Suppress("UNCHECKED_CAST") (_v2 as V)
} else {
val typedValue = initializer(thisRef, property)
_value = typedValue
typedValue
}
}
}
override fun setValue(thisRef: T, property: KProperty<*>, value: V) {
// 不论设置何值，都会被重置为空
synchronized(lock) {
_value = null
}
}
}