android kotlin - How to get substring from string

MainActivity.kt

package com.cfsuman.kotlintutorials

import android.os.Bundle
import android.text.method.ScrollingMovementMethod
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity


class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // get the widgets reference from XML layout
        val textView = findViewById<TextView>(R.id.textView)

        // make textview content scrollable
        textView.movementMethod = ScrollingMovementMethod()


        val string = "Lorem Ipsum is simply dummy text of the" +
                " printing and typesetting industry."

        textView.text = string

        // Returns a substring of this string that starts at the
        // specified startIndex and continues to the end of the string.
        val result = string.substring(
            50 // start index
        )

        textView.append("\n\n\n")
        textView.append("Substring start from index 50...\n")
        textView.append(result)


        /*
            documentation source kotlinlang.org
                Returns the substring of this string starting at the
                startIndex and ending right before the endIndex.
                    startIndex - the start index (inclusive).
                    endIndex - the end index (exclusive).
        */
        val result2 = string.substring(
            25, // start index inclusive
            65 // end index exclusive
        )

        textView.append("\n\n\n")
        textView.append("Substring start index 25 end index 65...\n")
        textView.append(result2)


        // Returns a substring specified by the given range of indices.
        val result3 = string.substring(
            15..60 // range
        )

        textView.append("\n\n\n")
        textView.append("Substring index range (15..60)...\n")
        textView.append(result3)
    }
}

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"
    android:background="#F8F8F8"
    android:padding="24dp">

    <TextView
        android:id="@+id/textView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:fontFamily="sans-serif"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>