How to implement endless RecyclerView in Kotlin

In this android kotlin source code example, we are going to implement endless RecyclerView in Kotlin.

You can copy and adopt this source code example to your Kotlin android project without reinventing the wheel.

Below is a step by step source code to implement endless RecyclerView in Kotlin.

activity_main.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=".recyclerView.RecyclerViewActivity8">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.kt

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.recyclerview.widget.RecyclerView
import androidx.recyclerview.widget.LinearLayoutManager
import com.bluapp.kotlinview.R
import androidx.recyclerview.widget.DividerItemDecoration
import android.widget.TextView
import android.view.LayoutInflater
import android.view.ViewGroup
import android.widget.Toast
import android.content.Context
import android.view.View


class RecyclerViewActivity8 : AppCompatActivity() {
    private var list: RecyclerView? = null
    private var recyclerAdapter: adapter? = null
    private var layoutManager: LinearLayoutManager? = null
    private val previousTotal = 0
    private var loading = false
    private val visibleThreshold = 5
    private var lastVisibleItemPosition: Int = 0
    private var visibleItemCount: Int = 0
    private var totalItemCount: Int = 0


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_recycler_view8)
        list = findViewById(R.id.list) as RecyclerView
        val country = arrayListOf<String>()
        country.add("Nigeria");
        country.add("China");
        country.add("USA");
        country.add("Ghana");
        country.add("Canada");
        country.add("Finland");
        country.add("Denmark");
        country.add("Argentina");
        country.add("Andorra");
        country.add("Angola");
        country.add("Benin");
        country.add("Brazil");
        country.add("Chile");
        country.add("Denmark");
        country.add("Egypt");
        country.add("Fiji");
        country.add("France");
        country.add("Togo");
        layoutManager = LinearLayoutManager(this)
        list!!.setLayoutManager(layoutManager)
        recyclerAdapter = adapter(this@RecyclerViewActivity8, country)
        list!!.addItemDecoration(DividerItemDecoration(list!!.getContext(), layoutManager!!.orientation))
        list!!.setAdapter(recyclerAdapter)
        list!!.addOnScrollListener(onScrollListener)

    }

    private val onScrollListener = object : RecyclerView.OnScrollListener() {
        override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
            super.onScrollStateChanged(recyclerView, newState)
        }

        override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
            super.onScrolled(recyclerView, dx, dy)
            visibleItemCount = layoutManager!!.getChildCount()
            totalItemCount = layoutManager!!.getItemCount()
            lastVisibleItemPosition = layoutManager!!.findLastVisibleItemPosition()
            if (!loading && lastVisibleItemPosition == totalItemCount - 1) {
                Toast.makeText(this@RecyclerViewActivity8, "The end, load next data", Toast.LENGTH_SHORT).show()
                loading = true
            }
        }
    }

    private inner class adapter(internal var context: Context, internal var mData: List<String>) : RecyclerView.Adapter<adapter.myViewHolder>() {
        override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): adapter.myViewHolder {
            val view =
                LayoutInflater.from(context).inflate(R.layout.recyclerview_adapter1, parent, false)
            return myViewHolder(view)
        }
        override fun onBindViewHolder(holder: adapter.myViewHolder, position: Int) {
            holder.country.text = mData[position]
        }
        override fun getItemCount(): Int {
            return mData.size
        }
        inner class myViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
            internal var country: TextView
            init {
                country = itemView.findViewById(R.id.country)
            }
        }
    }


}

recyclerview_adapter1.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:padding="10dp">

    <TextView
        android:id="@+id/country"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:text="Country"
        android:textColor="#000000"
        android:textSize="18sp"
        android:textStyle="bold" />

</RelativeLayout>