Button Example in Kotlin

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="androindian.MainActivity">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="hello"
        android:textSize="20sp"
        android:textColor="#234098"
        android:textAllCaps="true"
        android:textStyle="bold|italic"
        android:id="@+id/tv"
        android:typeface="monospace"
        android:gravity="center"/>
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Click Me"
        android:textSize="20sp"
        android:textColor="#234098"
        android:textAllCaps="true"
        android:textStyle="bold|italic"
        android:id="@+id/bt"
        android:typeface="monospace"
        android:gravity="center"/>
</LinearLayout>

MainActivity.kt

package com.androinidan.button

import androidx.appcompat.app.AppCompatActivity
import android.widget.TextView
import android.os.Bundle
import android.view.View
import android.widget.Button
import com.androinidan.button.R

class MainActivity : AppCompatActivity() {
    var textView: TextView? = null
    var button: Button? = null
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        textView = findViewById<View>(R.id.tv) as TextView
        button = findViewById<View>(R.id.bt) as Button
        button!!.setOnClickListener {
            textView!!.text = "Hi Hello Good morning"
        }
    }
}

output