No Adapter Attached RecyclerView - kotlin

Question

I want to implement my app. My app went smoothly, but I also got an error with 2022-05-31 14:14:32.663 8626-8626/id.kotlin.belajar E/RecyclerView: No adapter attached; skipping layout; skipping layout.
E/RecyclerView: No adapter attached; skipping layout; skipping layout
Home Activity:
class HomeActivity : DaggerAppCompatActivity(), HomeView {
#Inject
lateinit var presenter: HomePresenter
private lateinit var progressBar: ProgressBar
private lateinit var recyclerView: RecyclerView
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_home)
progressBar = findViewById(R.id.pb_home)
recyclerView = findViewById(R.id.rv_home)
presenter.discoverMovie()
}
override fun onShowLoading() {
progressBar.visibility = View.VISIBLE
}
override fun onHideLoading() {
progressBar.visibility = View.GONE
recyclerView.visibility = View.VISIBLE
}
override fun onResponse(results: List<Result<String>>) {
recyclerView.addItemDecoration(DividerItemDecoration(this#HomeActivity,
DividerItemDecoration.VERTICAL))
recyclerView.adapter = HomeAdapter(results)
}
override fun onFailure(t:Throwable) {
Log.e(HomeActivity::class.java.simpleName, "${t.printStackTrace()}")
}
}
Home Adapter:
class HomeAdapter (private val results: List<Result>):
RecyclerView.Adapter<HomeAdapter.HomeViewHolder>(){
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): HomeViewHolder {
return HomeViewHolder(
LayoutInflater
.from(parent.context).inflate(
R.layout.item_home,
parent,
false
)
)
}
override fun onBindViewHolder(holder: HomeViewHolder, position: Int){
holder.bind()
}
override fun getItemCount(): Int{
return results.count()
}
inner class HomeViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView){
fun bind() {
with(itemView) {
val title = findViewById<TextView>(R.id.original_title)
title.text
val overview = findViewById<TextView>(R.id.overview)
overview.text
}
}
}
}
Home Presenter:
class HomePresenter(private val view: HomeView, datasource: HomeDatasource) {
fun discoverMovie(){
view.onShowLoading()
val dataSource = Networkmodule.providesHttpAdapter(client =
OkHttpClient()).create(HomeDatasource::class.java)
dataSource.discoverMovie().enqueue(object : Callback<HomeResponse> {
override fun onResponse(call: Call<HomeResponse>, response: Response<HomeResponse>){
view.onHideLoading()
view.onResponse(((response.body()?.results ?: emptyList()) as List<Result<String>>))
}
override fun onFailure(call: Call<HomeResponse>, t:Throwable){
view.onHideLoading()
view.onFailure(t)
}
})
}
}
I need your help.

Answer 1

This is my .xml files:
activity_home:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
tools:context=".presentation.HomeActivity">
<androidx.appcompat.widget.Toolbar
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#color/white"
android:elevation="4dp"
app:layout_constraintTop_toTopOf="parent"
app:title="Belajar"
app:titleTextColor="#color/black"/>
<ProgressBar
android:id="#+id/pb_home"
style="#style/Widget.AppCompat.ProgressBar"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:indeterminate="true"
android:indeterminateTint="#color/black"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
tools:visibility="gone" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/rv_home"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingTop="?android:attr/actionBarSize"
android:scrollbars="vertical"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
tools:listitem="#layout/item_home" />
</androidx.constraintlayout.widget.ConstraintLayout>

Answer 2

I can see two major problems here :
Adapter instantiation
You do not need to re-instantiate the adapter each time you receive data.
Just instanciate it in the onCreate method with an empty list and update the list each time you have new data (don't forget to call notify method).
And attach the adapter to the recyclerView in the onCreate method as well
Exemple
In your activity you need to :
Declare and instantiate your Adapter as a class attribute.
In the onCreate method attach it to the recyclerView
On the onResponse method call a new method of your adapter called " update "
class HomeActivity : DaggerAppCompatActivity(), HomeView {
#Inject
lateinit var presenter: HomePresenter
private lateinit var progressBar: ProgressBar
private lateinit var recyclerView: RecyclerView
private val homeAdapter = HomeAdapter(emptyList())
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_home)
progressBar = findViewById(R.id.pb_home)
recyclerView = findViewById(R.id.rv_home)
recyclerView.adapter = homeAdapter
presenter.discoverMovie()
}
override fun onShowLoading() {
progressBar.visibility = View.VISIBLE
}
override fun onHideLoading() {
progressBar.visibility = View.GONE
recyclerView.visibility = View.VISIBLE
}
override fun onResponse(results: List<Result<String>>) {
recyclerView.addItemDecoration(DividerItemDecoration(this#HomeActivity,
DividerItemDecoration.VERTICAL))
homeAdapter.update(results)
}
override fun onFailure(t:Throwable) {
Log.e(HomeActivity::class.java.simpleName, "${t.printStackTrace()}")
}
}
In your adapter :
Make results a mutableList
Create the update method
Clear the results list
Add your newResults list to your list
notifyDataSetChanged to redraw the list with new values
class HomeAdapter (private val results: MutableList<Result>):
RecyclerView.Adapter<HomeAdapter.HomeViewHolder>(){
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): HomeViewHolder {
return HomeViewHolder(
LayoutInflater
.from(parent.context).inflate(
R.layout.item_home,
parent,
false
)
)
}
override fun onBindViewHolder(holder: HomeViewHolder, position: Int){
holder.bind()
}
override fun getItemCount(): Int{
return results.count()
}
fun update(newResults: List<Result>) {
results.apply {
clear()
addAll(newResults)
}
notifyDataSetChanged()
}
inner class HomeViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView){
fun bind() {
with(itemView) {
val title = findViewById<TextView>(R.id.original_title)
title.text
val overview = findViewById<TextView>(R.id.overview)
overview.text
}
}
}
}
Layout manager missing ?
We don't have your xml code so I don't know if you added the layoutManager on the xml like this (assuming you want a linearManager) :
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
You can do it programaticaly using the layoutManager attribute on the recyclerView :
recyclerView.layoutManager = LinearLayoutManager()
You can set it in the onCreate method (if it is an activity) or onViewCreated (if it's a fragment) before attaching your adapter to the recyclerView
To avoid errors like that, the best way is to setup your recyclerView as soon as possible in the activity (onCreate) or fragment (onViewCreated) lifecycle.