I'm newbie in coding, so I want to ask more experienced programmers how to do it right.
I have 2 functions, first from Facebook SDK and second from AppsFlyerLib.
Can you tell me if there is right option to wait results from this functions please.
Here example of code:
class MainActivity: AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?, persistentState: PersistableBundle?) {
super.onCreate(savedInstanceState, persistentState)
var linkdataPlusApps = ""
//Getting Link Data
val linkdataHandler = object : AppLinkData.CompletionHandler {
override fun onDeferredAppLinkDataFetched(appLinkData: AppLinkData?) {
linkdataPlusApps += appLinkData.toString()
}
}
AppLinkData.fetchDeferredAppLinkData(this, linkdataHandler)
//Gettings Apps
val appsdataHandler = object : AppsFlyerConversionListener {
override fun onConversionDataSuccess(p0: MutableMap<String, Any>?) {
linkdataPlusApps += p0.toString()
}
override fun onConversionDataFail(p0: String?) {}
override fun onAppOpenAttribution(p0: MutableMap<String, String>?) {}
override fun onAttributionFailure(p0: String?) {}
}
AppsFlyerLib.getInstance().init("APPS_KEY", appsdataHandler, this).start(this)
//Here I wanna take this data and put in another activity
val intent = Intent(this, NextActivity::class.java)
intent.putExtra("FetchedData", linkdataPlusApps)
startActivity(intent)
}}
But this code doesn't work because Activity started before data was fetched so string is empty.
I solved this by chaining code, but I'm sure that is dirty-coding.
How I did
class MainActivity: AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?, persistentState: PersistableBundle?) {
super.onCreate(savedInstanceState, persistentState)
var linkdataPlusApps = ""
//Getting Link Data
val linkdataHandler = object : AppLinkData.CompletionHandler {
override fun onDeferredAppLinkDataFetched(appLinkData: AppLinkData?) {
linkdataPlusApps += appLinkData.toString()
val appsdataHandler = object : AppsFlyerConversionListener {
override fun onConversionDataSuccess(p0: MutableMap<String, Any>?) {
linkdataPlusApps += p0.toString()
val intent = Intent(this#MainActivity, NextActivity::class.java)
intent.putExtra("FetchedData", linkdataPlusApps)
startActivity(intent)
}
override fun onConversionDataFail(p0: String?) {}
override fun onAppOpenAttribution(p0: MutableMap<String, String>?) {}
override fun onAttributionFailure(p0: String?) {}
}
AppsFlyerLib.getInstance().init("APPS_KEY", appsdataHandler, this#MainActivity).start(this#MainActivity)
}
}
AppLinkData.fetchDeferredAppLinkData(this, linkdataHandler)
}
}
So code starts from fetching AppLinkData, and when fetched, starting fetching apps, and only then starting second activity with right string.
Can I do it in another way?
Related
I'm pretty new to kotlin, and I feel pretty much overwhelmed by it. I'd like to ask - how I can display any data from MutableLiveData? I've tried to Log it, but it doesn't seem to work. I've already added the internet permission to the manifest. Here's the code:
ApiServices
interface ApiServices {
#GET("/fixer/latest/")
fun getRatesData(
#Query("base") base: String,
#Query("apikey") apikey: String
): Call<CurrencyModel>
companion object {
private const val url = "https://api.apilayer.com/"
var apiServices: ApiServices? = null
fun getInstance(): ApiServices {
if (apiServices == null) {
val retrofit = Retrofit.Builder()
.baseUrl(url)
.addConverterFactory(GsonConverterFactory.create())
.build()
apiServices = retrofit.create(ApiServices::class.java)
}
return apiServices!!
}
}
}
Repository
class CurrencyRepository constructor(private val apiServices: ApiServices) {
fun getLatestRates() = apiServices.getRatesData("EUR", "API_KEY");
}
ViewModel
class CurrencyViewModel constructor(private val currencyRepository: CurrencyRepository) :
ViewModel() {
val currencyRatesList = MutableLiveData<CurrencyModel>()
val errorMessage = MutableLiveData<String>()
fun getLatestRates() {
val response = currencyRepository.getLatestRates();
response.enqueue(object : retrofit2.Callback<CurrencyModel> {
override fun onResponse(
call: retrofit2.Call<CurrencyModel>,
response: Response<CurrencyModel>
) {
currencyRatesList.postValue(response.body())
}
override fun onFailure(call: retrofit2.Call<CurrencyModel>, t: Throwable) {
errorMessage.postValue(t.message)
}
})
}
}
FactoryViewModel
class CurrencyViewModelFactory constructor(private val repository: CurrencyRepository) :
ViewModelProvider.Factory {
override fun <T : ViewModel?> create(modelClass: Class<T>): T {
return if (modelClass.isAssignableFrom(CurrencyViewModel::class.java)) {
CurrencyViewModel(this.repository) as T
}else{
throw IllegalArgumentException("Couldn't found ViewModel")
}
}
}
MainActivity
class MainActivity : AppCompatActivity() {
private val retrofitService = ApiServices.getInstance()
lateinit var viewModel: CurrencyViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
viewModel = ViewModelProvider(this, CurrencyViewModelFactory(CurrencyRepository(retrofitService)))
.get(CurrencyViewModel::class.java)
viewModel.currencyRatesList.observe(this, Observer {
Log.d(TAG, "onCreate: $it")
})
viewModel.errorMessage.observe(this, Observer {
viewModel.getLatestRates()
})
}
}
You never call viewModel.getLatestRates() in your onCreate() to fetch an initial value for your LiveData, so it never emits anything to observe. The only place you have called it is inside your error listener, which won't be called until a fetch returns an error.
Side note, I recommend naming the function "fetchLatestRates()". By convention, "get" implies that the function returns what it's getting immediately rather than passing it to a LiveData later when its ready.
And a tip. Instead of this:
class MainActivity : AppCompatActivity() {
lateinit var viewModel: CurrencyViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
// ...
viewModel = ViewModelProvider(this, CurrencyViewModelFactory(CurrencyRepository(retrofitService)))
.get(CurrencyViewModel::class.java)
//...
}
}
You can do this for the same result:
class MainActivity : AppCompatActivity() {
val viewModel: CurrencyViewModel by viewModels(CurrencyViewModelFactory(CurrencyRepository(retrofitService)))
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
// ...
}
}
I am discovering Kotlin and android app dev. I fail to get data from my room database (because of Cannot access database on the main thread). So I try with lifecyclescope.
The concerned code, in Fragment onViewCreated function, is :
lifecycleScope.launch {
withContext(Dispatchers.Default) {
val accountConfiguration = viewModel.get();
println("{${accountConfiguration}}")
}
}
The called function (in viewModel) is :
fun get() = viewModelScope.launch {
repository.get()
}
There is the "full" code (simplified), Entity & DAO :
#Entity
data class AccountConfiguration(
#PrimaryKey val server_address: String,
#ColumnInfo(name = "user_name") val user_name: String,
// [...]
)
#Dao
interface AccountConfigurationDao {
#Query("SELECT * FROM accountconfiguration LIMIT 1")
fun flow(): Flow<AccountConfiguration?>
#Query("SELECT * FROM accountconfiguration LIMIT 1")
suspend fun get(): AccountConfiguration?
// [...]
}
Repository :
package fr.bux.rollingdashboard
import androidx.annotation.WorkerThread
import kotlinx.coroutines.flow.Flow
class AccountConfigurationRepository(private val accountConfigurationDao: AccountConfigurationDao) {
val accountConfiguration: Flow<AccountConfiguration?> = accountConfigurationDao.flow()
// [...]
#Suppress("RedundantSuspendModifier")
#WorkerThread
suspend fun get() : AccountConfiguration? {
return accountConfigurationDao.get()
}
}
ViewModel & Factory :
class AccountConfigurationViewModel(private val repository: AccountConfigurationRepository) : ViewModel() {
val accountConfiguration: LiveData<AccountConfiguration?> = repository.accountConfiguration.asLiveData()
// [...]
fun get() = viewModelScope.launch {
repository.get()
}
// [...]
}
class AccountConfigurationViewModelFactory(private val repository: AccountConfigurationRepository) : ViewModelProvider.Factory {
override fun <T : ViewModel> create(modelClass: Class<T>): T {
if (modelClass.isAssignableFrom(AccountConfigurationViewModel::class.java)) {
#Suppress("UNCHECKED_CAST")
return AccountConfigurationViewModel(repository) as T
}
throw IllegalArgumentException("Unknown ViewModel class")
}
}
Fragment :
class AccountConfigurationFragment : Fragment() {
private var _binding: AccountConfigurationFragmentBinding? = null
// This property is only valid between onCreateView and
// onDestroyView.
private val binding get() = _binding!!
private val viewModel: AccountConfigurationViewModel by activityViewModels {
AccountConfigurationViewModelFactory(
(activity?.application as RollingDashboardApplication).account_configuration_repository
)
}
lateinit var accountConfiguration: AccountConfiguration
// [...]
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
binding.buttonGoBackMain.setOnClickListener {
findNavController().navigate(R.id.action_AccountConfigurationFragment_to_DashboardFragment)
}
lifecycleScope.launch {
withContext(Dispatchers.Default) {
val accountConfiguration = viewModel.get();
println("{${accountConfiguration}}")
}
}
binding.buttonSave.setOnClickListener {
save()
}
}
// [...]
}
In your current code,
lifecycleScope.launch {
withContext(Dispatchers.Default) {
val accountConfiguration = viewModel.get();
println("{${accountConfiguration}}")
}
}
viewModel.get() is not a suspend function, so it returns immediately and proceeds to the next line. It actually returns the Job created by viewModelScope.launch().
If you want your coroutine to wait for the result before continuing you should make the get() function suspend and return the AccountConfiguration?
suspend fun get(): AccountConfiguration? {
return repository.get()
}
You need not change dispatchers to Dispatchers.Default because Room itself will switch to a background thread before executing any database operation.
Right now if there is a configuration change while coroutines inside lifecyclerScope are running, everything will get cancelled and restarted.
A better way would have been to put the suspending calls inside the ViewModel and expose a LiveData/Flow to the UI.
The problem is the viewModel function :
fun get() = viewModelScope.launch {
repository.get()
}
This function must be the coroutine instead launch the coroutine itself. Correct code is :
suspend fun get(): AccountConfiguration? {
return repository.get()
}
I don't know why it's says me that "java.lang.IndexOutOfBoundsException: Index: 0, Size: 0"
I've been searching for this since 2 hours, and i don't know why there is this problem now, can you help me ? I want to pass data from apiRest into another activity with intent and putExtra/getExtra (I will do with firebase later, more simple and more easy way).
Main Activity
package com.mehdi.myapplication
class MainActivity : AppCompatActivity(), ListAdapter.OnItemClickListener {
lateinit var userAdapter: ListAdapter
var lm = LinearLayoutManager(this)
private val users: MutableList<Results> = mutableListOf()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
initView()
getClassApiRet()
}
override fun onItemClick(position: Int) {
Toast.makeText(this, position.toString(), Toast.LENGTH_LONG).show()
val intent = Intent(this, DetailPageActivity::class.java)
intent.putExtra("email", users[position].email)
startActivity(intent)
}
fun initView() {
UserRecycleView.layoutManager = lm
userAdapter = ListAdapter(this, this)
UserRecycleView.adapter = userAdapter
}
fun getClassApiRet() {
val retro = Instance().getRetroInstance().create(ClassApiRest::class.java)
retro.getData().enqueue(object : Callback<ClassApi> {
override fun onResponse(call: Call<ClassApi>, response: Response<ClassApi>) {
val users = response.body()
runOnUiThread {
userAdapter.setUsers(users?.results!!)
}
}
override fun onFailure(call: Call<ClassApi>, t: Throwable) {
Log.e("Failed", t.message.toString())
}
})
}
}
UserInfo
class ClassApi {
#SerializedName("results")
#Expose
val results: List<Results>? = null
}
class Results {
#SerializedName("name")
#Expose
val name: Name? = null
#SerializedName("email")
#Expose
val email: String? = null
#SerializedName("login")
#Expose
val login: Login? = null
#SerializedName("picture")
#Expose
val picture: Picture? = null
}
class Name {
#SerializedName("title")
#Expose
val title: String? = null
#SerializedName("first")
#Expose
val first: String? = null
#SerializedName("last")
#Expose
val last: String? = null
}
class Login {
#SerializedName("username")
#Expose
val username: String? = null
}
class Picture {
#SerializedName("medium")
#Expose
val medium: String? = null
#SerializedName("large")
#Expose
val large: String? = null
}
ListAdapter
class ListAdapter(val context: Context, val listener: OnItemClickListener): RecyclerView.Adapter<ListAdapter.UsersViewHolder>() {
private val users: MutableList<Results> = mutableListOf()
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ListAdapter.UsersViewHolder {
return UsersViewHolder(LayoutInflater.from(context).inflate(R.layout.row_user_list, parent, false))
}
override fun onBindViewHolder(holder: ListAdapter.UsersViewHolder, position: Int) {
holder.bindModel(users[position])
}
override fun getItemCount(): Int {
return users.size
}
fun setUsers(results: List<Results>) {
users.clear()
users.addAll(results)
notifyDataSetChanged()
}
inner class UsersViewHolder(item: View) : RecyclerView.ViewHolder(item), View.OnClickListener {
val UserImage: CircleImageView = item.findViewById(R.id.UserImage)
val UserName: TextView = item.findViewById(R.id.UserName)
val UserPseudo: TextView = item.findViewById(R.id.UserPseudo)
init {
itemView.setOnClickListener(this)
}
fun bindModel(b: Results) {
UserName.text = b.name?.first
UserPseudo.text = b.login?.username
val url = b.picture?.medium
Glide.with(UserImage)
.load(url)
.placeholder(R.drawable.ic_launcher_background)
.error(R.drawable.ic_launcher_background)
.fallback(R.drawable.ic_launcher_foreground)
.into(UserImage)
}
override fun onClick(v: View?) {
val position = adapterPosition
if (position != RecyclerView.NO_POSITION) {
listener.onItemClick(position)
}
}
}
interface OnItemClickListener {
fun onItemClick(position: Int)
}
}
Edit !!!
I think the probleme is with the position and the interface, he can't get data.
ListAdapter
override fun onClick(v: View?) {
val position = adapterPosition
if (position != RecyclerView.NO_POSITION) {
listener.onItemClick(position)
}
}
}
interface OnItemClickListener {
fun onItemClick(position: Int)
}
Main Activity
override fun onItemClick(position: Int) {
Toast.makeText(this, users[position].email.toString(), Toast.LENGTH_LONG).show()
val intent = Intent(this, DetailPageActivity::class.java)
//intent.putExtra("lolipop", users[position].toString())
startActivity(intent)
}
Your response listener is passing the list of users to the ListAdapter, but it doesn't do anything to the MainActivity's users property, so that list remains empty. Then your item click listener tries to access the user by index in that empty list.
I would remove the users property from the Activity since there is no practical use for it. In your ListAdapter, change the onItemClick function of the OnItemClickListener to pass the actual User instead of the User's position in the data. You can get the actual User using the adapterPosition from within the adapter, since it owns the users list.
Edit: I'm suggesting to change your listener function signature to return an item directly. There's no reason the Activity should have to find the item in the collection when the Adapter can just provide it directly.
// ListAdapter:
override fun onClick(v: View?) {
listener.onItemClick(users[adapterPosition])
}
interface OnItemClickListener {
fun onItemClick(results: Results)
}
I'm parsing API and it's logging in the logcat, but I have a problem while retrieving it and using that data in a recycleview. These are my code snippets:
class MainActivity : AppCompatActivity() {
private val users = arrayListOf<User>()
private lateinit var adapter: RecyclerViewAdapter
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
init()
}
private fun init() {
adapter = RecyclerViewAdapter(users)
recyclerView.layoutManager = LinearLayoutManager(this)
recyclerView.adapter = adapter
val myViewModel : UsersViewModel by viewModel()
myViewModel.getAllUsers().observe(this, Observer {
users.add(it)
adapter.notifyDataSetChanged()
})
myViewModel.getUsers()
d("allUsers", users.size.toString())
}
}
I cannot set the data in a recyclerview, can anyone give me a hint? I could not find a proper source or code snippet to understand how I'm able to parse the data using a converter.
class UsersRequest {
private var retrofit = Retrofit.Builder()
.baseUrl("https://reqres.in/api/")
.addConverterFactory(ScalarsConverterFactory.create())
.build()
private var service = retrofit.create(ApiService::class.java)
interface ApiService {
#GET("users?page=1")
fun getRequest(): Call<String>
}
fun getRequest(callback: CustomCallback) {
val call = service.getRequest()
call.enqueue(onCallback(callback))
}
private fun onCallback(callback: CustomCallback): Callback<String> = object : Callback<String> {
override fun onFailure(call: Call<String>, t: Throwable) {
d("response", "${t.message}")
callback.onFailure(t.message.toString())
}
override fun onResponse(call: Call<String>, response: Response<String>) {
d("response", "${response.body()}")
callback.onSuccess(response.body().toString())
}
}
}
class RecyclerViewAdapter(private val users: ArrayList<User>) :
RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
return ViewHolder(
LayoutInflater.from(parent.context).inflate(
R.layout.user_layout,
parent,
false
)
)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
return holder.onBind()
}
override fun getItemCount() = users.size
private lateinit var user:User
inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
fun onBind() {
user = users[adapterPosition]
itemView.name.text = user.first_name
}
}
}
User(
val id: Int,
val email: String,
val first_name: String,
val last_name: String,
val avatar: String
)
with adapter class RecyclerViewAdapter(private val users: MutableList<User>) : RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder>() { ...
Add this method to your adapter :
fun setUsers(usersList: List<User>) {
this.users.clear()
this.users.addAll(usersList)
notifyDataSetChanged()
}
and in MainActivity simply put :
myViewModel.getAllUsers().observe(this, Observer {
users -> hideLoading() // If you have a progress bar, here you can hide it
users?.let {
adapter.setUsers(users) }
})
Hello :) I'm working on app that shows popular movies and some details about each of them. I created a RecyclerView where information should be displayed. I'm stuck with getting and displaying data. I'm using https://www.themoviedb.org/ page for api.
I was following these steps: http://imakeanapp.com/make-a-movies-app-using-tmdb-api-part-4-networking-using-retrofit-library/ , but it's written in Java and I need code in Kotlin. I converted by myself a part of the code, here is what I have:
in Movie.kt
data class Movie (
#SerializedName("id") val id: Int,
#SerializedName("title") val title: String,
#SerializedName("poster_path") val posterPath: String,
#SerializedName("release_date") val releaseDate: String,
#SerializedName("vote_average") val rating: Float
)
in MoviesResponse.kt
data class MoviesResponse (
#SerializedName("page") val page: Int,
#SerializedName("total_results") val totalResults: Int,
#SerializedName("results") val movies: List<Movie>,
#SerializedName("total_pages") val totalPages: Int
)
in TMDbApi.kt
interface TMDbApi {
#GET("movie/popular")
fun getPopularMovies (
#Query("api_key") apiKey: String,
#Query("language") language: String,
#Query("page") page: Int
): Call<List<MoviesResponse>>
}
in OnGetMoviesCallback.kt
interface OnGetMoviesCallback {
fun onSuccess(movies: List<Movie>)
fun onError()
}
in MainAdapter.kt
class MainAdapter: RecyclerView.Adapter<CustomHolder>(){
var movies: List<Movie> = listOf()
fun MainAdapter(movies: List<Movie>) {
this.movies = movies
}
override fun getItemCount(): Int {
return movies.size
}
override fun onBindViewHolder(holder: CustomHolder, position: Int) {
holder.bind(movies.get(position))
holder?.setOnClick()
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CustomHolder {
val layoutInflater = LayoutInflater.from(parent?.context)
val cellForRow = layoutInflater.inflate(R.layout.movie_row, parent, false)
return CustomHolder(cellForRow)
}
}
class CustomHolder(view: View): RecyclerView.ViewHolder(view){
fun bind(result: Movie){
itemView.title.text = result.title
itemView.release_date.text = result.releaseDate
}
}
in MoviesRepository.kt
val BASE_URL: String = "https://api.themoviedb.org/3/"
val LANGUAGE: String = "en-US"
data class MoviesRepository (
val repositroy: MoviesRepository,
val api: TMDbApi
)
object getInstance{
val retrofit: TMDbApi = Retrofit.Builder()
.addConverterFactory(GsonConverterFactory.create())
.client(OkHttpClient().newBuilder().build())
.baseUrl(BASE_URL)
.build()
.create(TMDbApi::class.java)
}
in AllMoviesActivity.kt
class AllMoviesActivity : AppCompatActivity(), Callback<List<MoviesResponse>> {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_all_movies)
rw_main.layoutManager = LinearLayoutManager(this)
rw_main.adapter = MainAdapter()
getMovies()
}
private fun getMovies() {
getInstance.retrofit.getPopularMovies("2B0b0e8d104f0d6130a4fc67848f89e107", LANGUAGE, 1).enqueue(this)
}
override fun onResponse(call: retrofit2.Call<List<MoviesResponse>>, response: Response<List<MoviesResponse>>) {
val moviesResponse = response.body() ?: listOf()
Log.d("Results", moviesResponse.toString())
}
override fun onFailure(call: retrofit2.Call<List<MoviesResponse>>, t: Throwable) {
Toast.makeText(this, "Failed", Toast.LENGTH_SHORT).show()
}
}
And I have added in Manifest file Internet permission. When I run this, I get 'Failed' Toast and I don't see RecyclerView. Can you tell me what I'm missing or what's wrong? I've been searching on the Internet solutions but with no results. Hope you could help me. Thanks!
Looks like you are missing something small. After making a call to the API on Postman, Here's what you expect on your response body:
{
"page": 1,
"total_results": 10000,
"total_pages": 500,
"results": [...
}
Having brought that up, lets digest your lines, in TMDbApi.kt, you have indicated that your expected response is a List<MoviesResponse> which conflicts the response you receive as it is a JSON of type MoviesResponse,
Fix:
...): Call<List<MoviesResponse>>
}
to:
): Call<MoviesResponse>
}
The rest are small fixes to align your response handling.
Head over to AllMoviesActivity.kt and change the following:
class AllMoviesActivity : AppCompatActivity(), Callback<List<MoviesResponse>> {
to
class MainActivity : AppCompatActivity(), Callback<MoviesResponse>
Then on the callback functions, change signatures like so:
override fun onResponse(call: retrofit2.Call<List<MoviesResponse>>, response: Response<List<MoviesResponse>>) {
val moviesResponse = response.body() ?: listOf() ...
to:
override fun onResponse(call: Call<MoviesResponse>, response:Response<MoviesResponse>
) {
val moviesResponse = response.body()//type will be inferred ...
Then finally,
override fun onFailure(call: retrofit2.Call<List<MoviesResponse>>, t: Throwable) {
to:
override fun onFailure(call: Call<MoviesResponse>, t: Throwable) {
That's the basic to get the response and keep the Failure toast at bay.
Parting shot
Make the logs your friend, they can reveal the messy & smallest misses