How to create RecyclerView LinearLayoutManager in Kotlin

In this android kotlin source code example, we are going to create RecyclerView LinearLayoutManager 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 create RecyclerView LinearLayoutManager 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.RecyclerViewActivity4">

    <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 android.content.Context
import android.graphics.Canvas
import android.graphics.drawable.Drawable
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.core.content.ContextCompat
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.bluapp.kotlinview.R

class RecyclerViewActivity4 : AppCompatActivity() {
    private var list: RecyclerView? = null
    private var recyclerAdapter: adapter? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_recycler_view4)
        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("Togo")

        val layoutManager = LinearLayoutManager(this)
        list!!.layoutManager = layoutManager
        recyclerAdapter = adapter(this@RecyclerViewActivity4, country)
        list!!.addItemDecoration(CustomDividerItemDecoration(this@RecyclerViewActivity4))
        list!!.adapter = recyclerAdapter
    }

    private inner class CustomDividerItemDecoration(context: Context) : RecyclerView.ItemDecoration() {
        private val drawableline: Drawable?
        init {
            drawableline = ContextCompat.getDrawable(context, R.drawable.recyclerline)
        }
        override fun onDrawOver(c: Canvas, parent: RecyclerView, state: RecyclerView.State) {
            val left = parent.paddingLeft
            val right = parent.width - parent.paddingRight
            val childCount = parent.childCount
            for (i in 0 until childCount) {
                val child = parent.getChildAt(i)
                val params = child.layoutParams as RecyclerView.LayoutParams
                val top = child.bottom + params.bottomMargin
                val bottom = top + drawableline!!.intrinsicHeight
                drawableline.setBounds(left, top, right, bottom)
                drawableline.draw(c)
            }
        }
    }

    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>

res/drawable/recyclerline.xml

<?xml version="1.0" encoding="utf-8"?>
<shape
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <size
        android:height="1dp"
        android:width="1dp" />
    <solid
        android:color="@color/colorAccent" />
</shape>

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