Seekbar in Kotlin

Android SeekBar is the extension of ProgressBar. SeekBar allows the user to change the value using touch event/draggable thumb/left right arrow keys. The user can increase the value by dragging the thumb right   or by pressing the right arrow key. Similarly the user can decrease the value by dragging the thumb left or by pressing the left arrow key.

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <SeekBar
        android:id="@+id/seekBar1"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="26dp"
        android:max="10"/>

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_below="@+id/seekBar1"
        android:layout_marginLeft="29dp"
        android:layout_marginTop="14dp" />

</RelativeLayout>

MainActivity.kt

package com.androidian.seekbar

import android.os.Bundle
import android.view.View
import android.widget.SeekBar
import android.widget.SeekBar.OnSeekBarChangeListener
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {
    private var seekBar: SeekBar? = null
    private var textView: TextView? = null
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        seekBar = findViewById<View>(R.id.seekBar1) as SeekBar
        textView = findViewById<View>(R.id.textView1) as TextView
        // Initialize the textview with '0'
        textView!!.text = seekBar!!.progress.toString() + "/" + seekBar!!.max
        seekBar!!.setOnSeekBarChangeListener(
            object : OnSeekBarChangeListener {
                var progress = 0
                override fun onProgressChanged(
                    seekBar: SeekBar,
                    progresValue: Int, fromUser: Boolean
                ) {
                    progress = progresValue
                }

                override fun onStartTrackingTouch(seekBar: SeekBar) {
                    // Do something here,
                    //if you want to do anything at the start of
                    // touching the seekbar
                }

                override fun onStopTrackingTouch(seekBar: SeekBar) {
                    // Display the value in textview
                    textView!!.text = progress.toString() + "/" + seekBar.max
                }
            })
    }
}