Android Kotlin recyclerview onScrollListener 不起作用

Question

I want to implement recyclerview onScrollListener. Here is my code.

MainActivity.kt:

class MainActivity : AppCompatActivity() {

lateinit var restModel : RestModel
var apiResponseList : MutableList<ApiResponse> = arrayListOf()
lateinit var itemAdapter: ItemAdapter
var handler: Handler = Handler()
lateinit var layoutManager : LinearLayoutManager



override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.main_activity)
    mainPresenter = MainPresenter(this)
    val currentDate = mainPresenter.convertDate()
    mainPresenter.makeACall(currentDate)
}

override fun assignResponseToRecyclerview(apiResponse: ApiResponse?) {
    var _layoutManager = LinearLayoutManager(this)
    rv_api_response.apply {
        layoutManager = _layoutManager
        apiResponseList.add(apiResponse!!)
        itemAdapter = ItemAdapter(apiResponseList)
        adapter = itemAdapter

        addOnScrollListener(object : RecyclerView.OnScrollListener() {
            override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
                super.onScrolled(recyclerView, dx, dy)
                Log.e("z","z");
            }
        })
    }
}
}

main_activity.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".view.MainActivity">

<androidx.core.widget.NestedScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv_api_response"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginStart="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginBottom="8dp"/>

</androidx.core.widget.NestedScrollView>

<ProgressBar
    android:id="@+id/progress_bar"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:visibility="visible"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />


</androidx.constraintlayout.widget.ConstraintLayout>

Why isn't my recyclerview's onScrollListener called (I assume that because my Log text not shows up)?

I probably need to add that my List items are not fullscreen, it's just one element, but I want to call on him this onScrollListener.

I skipped MVP architectural pattern complexity between classes, just essential code. But if you need something more just ask.

Thank you in advance!

Answer 1

Weird!! It should have worked. I just tried having a simple recycler view with similar code and everything worked for me.

One minor possible thing, I hope you are looking at the error part of logcat for your log. Since you have used Log.e .

Another possible thought could be to try adding the listener from onCreate provided your callback and listener attachment are not related.